Co-reporter:Diego A. Gómez-Gualdrón, Timothy C. Wang, Paula García-Holley, Ruth M. Sawelewa, Edwin Argueta, Randall Q. Snurr, Joseph T. Hupp, Taner Yildirim, and Omar K. Farha
ACS Applied Materials & Interfaces October 4, 2017 Volume 9(Issue 39) pp:33419-33419
Publication Date(Web):April 7, 2017
DOI:10.1021/acsami.7b01190
Metal–organic frameworks (MOFs) are porous crystalline materials that are promising for adsorption-based, on-board storage of hydrogen in fuel-cell vehicles. Volumetric and gravimetric hydrogen capacities are the key factors that determine the size and weight of the MOF-filled tank required to store a certain amount of hydrogen for reasonable driving range. Therefore, they must be optimized so the tank is neither too large nor too heavy. Because the goals of maximizing MOF volumetric and gravimetric hydrogen adsorption loadings individually are incompatible, an in-depth understanding of the trade-off between MOF volumetric and gravimetric loadings is necessary to achieve the best compromise between these properties. Here we study, both experimentally and computationally, the trade-off between volumetric and gravimetric cryo-adsorbed hydrogen deliverable capacity by taking an isoreticular series of highly stable zirconium MOFs, NU-1101, NU-1102, and NU-1103 as a case study. These MOFs were studied under recently proposed operating conditions: 77 K/100 bar →160 K/5 bar. We found the difference between highest and lowest measured deliverable capacity in the MOF series to be ca. 40% gravimetrically, but only ca. 10% volumetrically. From our molecular simulation results, we found hydrogen “monolayer” adsorption to be proportional to the surface area, whereas hydrogen “pore filling” adsorption is proportional to the pore volume. Thus, we found that the higher variability in gravimetric deliverable capacity in contrast to the volumetric capacity, occurs due to the proportional relation between gravimetric surface area and pore volume in the NU-110x series in contrast to the inverse relation between volumetric surface area and void fraction. Additionally, we find better correlations with geometric surface areas than with BET areas. NU-1101 presents the highest measured volumetric performance with 46.6 g/L (9.1 wt %), whereas NU-1103 presents the highest gravimetric one with 12.6 wt % (43.2 g/L).Keywords: cryoadsorption; energy storage; molecular modeling; nnoporous materials; zirconium MOFs;
Co-reporter:Zhanyong Li, Aaron W. Peters, Ana E. Platero-Prats, Jian Liu, Chung-Wei Kung, Hyunho Noh, Matthew R. DeStefano, Neil M. Schweitzer, Karena W. Chapman, Joseph T. Hupp, and Omar K. Farha
Journal of the American Chemical Society October 25, 2017 Volume 139(Issue 42) pp:15251-15251
Publication Date(Web):October 4, 2017
DOI:10.1021/jacs.7b09365
Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal–organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (<230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Using difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples, the promoter ions are sited between pairs of Zr6 nodes along the MOF c-axis, whereas the location of the cobalt ions varies with the promoter ions. These NU-1000-supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando X-ray absorption spectroscopy at the Co K-edge. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the following order: Mo(VI) < Ti(IV) < Al(III) < Zn(II) < Ni(II). The finding is attributed to increasing ease of formation of Co(III)–O• species and stabilization of a cobalt(III)-oxyl/propane transition state as the Lewis acidity of the promoter ions decreases. The results point to an increasing ability to fine-tune the structure-dependent activity of MOF-supported heterogeneous catalysts. Coupled with mechanistic studies—computational or experimental—this ability may translate into informed prediction of improved catalysts for propane ODH and other chemical reactions.
Co-reporter:Martino Rimoldi, Joseph T. Hupp, and Omar K. Farha
ACS Applied Materials & Interfaces October 11, 2017 Volume 9(Issue 40) pp:35067-35067
Publication Date(Web):September 20, 2017
DOI:10.1021/acsami.7b12303
Methyltrioxorhenium (ReO3Me) is introduced as the first rhenium atomic layer deposition (ALD) precursor and used to grow rhenium–aluminum oxide thin films in combination with trimethylaluminum (TMA–AlMe3). The growth rate of the smooth Re–Al oxide films, with general stoichiometry RexAlyO3x, has been monitored by in situ quartz crystal microbalance (QCM) and ex situ ellipsometry, and found to be 3.2 Å/cycle. X-ray photoelectron spectroscopy (XPS) revealed the mixed valent composition of the film with Re(III) species being the main component. In addition, ReO3Me has been successfully used to deposit rhenium oxide in NU-1000, a mesoporous zirconium-based metal–organic framework (MOF). The metalated MOF was found to retain porosity and crystallinity and to be catalytically active for ethene hydrogenation.Keywords: atomic layer deposition; gas flow; hydrogenation; metal−organic framework; rhenium oxide; thin film; trimethylaluminum;
Co-reporter:Mizuho Yabushita, Peng Li, Timur Islamoglu, Hirokazu Kobayashi, Atsushi Fukuoka, Omar K. Farha, and Alexander Katz
Industrial & Engineering Chemistry Research June 28, 2017 Volume 56(Issue 25) pp:7141-7141
Publication Date(Web):May 30, 2017
DOI:10.1021/acs.iecr.7b01164
This manuscript demonstrates the synthesis of selective Lewis-acid sites in a metal–organic framework (MOF) for glucose transformation to 5-hydroxymethylfurfural (HMF). These sites are synthesized via partial phosphate modification of zirconia-cluster nodes in MOF NU-1000, which titrates strong Lewis-acid sites that would lead to undesired side reactions. Our mechanistic study using isotope tracer analysis and kinetic isotope effect measurements reveals that an isomerization–dehydration mechanism mainly occurs on the MOF catalyst, where fructose is an intermediate. This mechanism suggests that dilute concentrations are favorable in order to suppress undesired intermolecular condensation of glucose/fructose/HMF and maximize HMF yield. We demonstrate both high yield and selectivity of HMF formation of 64% with the MOF catalyst, at an initial glucose concentration of 1 mM in water/2-propanol. In stark contrast, similar partial phosphate modification of a bulk zirconia yields a catalyst that exhibits poor HMF selectivity, while possessing nearly identical Brønsted acidity to the selective NU-1000-based catalyst.
Co-reporter:Cassandra T. Buru, Peng Li, B. Layla Mehdi, Alice Dohnalkova, Ana E. Platero-Prats, Nigel D. Browning, Karena W. Chapman, Joseph T. Hupp, and Omar K. Farha
Chemistry of Materials June 27, 2017 Volume 29(Issue 12) pp:5174-5174
Publication Date(Web):May 24, 2017
DOI:10.1021/acs.chemmater.7b00750
A Keggin-type polyoxometalate (H3PW12O40) was incorporated into a mesoporous Zr-based MOF (NU-1000) via an impregnation method in aqueous media, resulting in the hybrid material, PW12@NU-1000. The POM@MOF composite was characterized by a suite of physical methods, indicating the retention of crystallinity and high porosity of the parent MOF. The hybrid material was also stable to leaching in aqueous media at varying pH. Finally, the material was tested as a heterogeneous catalyst for the oxidation of 2-chloroethyl ethyl sulfide using hydrogen peroxide as the oxidant. PW12@NU-1000 was shown to have a higher catalytic activity than either of the individual constituents alone.
Co-reporter:Martino Rimoldi, Ashlee J. Howarth, Matthew R. DeStefano, Lu Lin, Subhadip Goswami, Peng Li, Joseph T. Hupp, and Omar K. Farha
ACS Catalysis February 3, 2017 Volume 7(Issue 2) pp:997-997
Publication Date(Web):December 30, 2016
DOI:10.1021/acscatal.6b02923
Metal–organic frameworks (MOFs) are highly versatile materials that find applications in several fields. Highly stable zirconium/hafnium-based MOFs were recently introduced and nowadays represent a rapidly growing family. Their unique and intriguing properties make them privileged materials and outstanding candidates in heterogeneous catalysis, finding use either as catalysts or catalyst supports. Various techniques have been developed to incorporate active species into Zr-MOFs, giving rise to catalysts that often demonstrate higher performances or unusual activity when compared with their homogeneous analogues. Catalytic functions are commonly incorporated at the zirconium-oxide node, at the linker, or encapsulated in the pores. Representative examples are discussed, and advantages in adopting Zr- and Hf-MOFs in catalytic applications are highlighted.Keywords: catalysis; encapsulation; hafnium; linker; metal−organic framework; node; zirconium;
Co-reporter:William L. HoffeditzHo-Jin Son, Michael J. Pellin, Omar K. Farha, Joseph T. Hupp
ACS Applied Materials & Interfaces December 21, 2016 Volume 8(Issue 50) pp:
Publication Date(Web):November 30, 2016
DOI:10.1021/acsami.6b10844
Organic and porphyrin-based chromophores are prevalent in liquid-junction photovoltaic and photocatalytic solar-cell chemistry; however, their long-term air and light instability may limit their practicality in real world technologies. Here, we describe the protection of a zinc porphyrin dye, adsorbed on nanoparticulate TiO2, from air and light degradation by a protective coating of alumina grown with a previously developed post-treatment atomic layer deposition (ALD) technique. The protective Al2O3 ALD layer is deposited using dimethylaluminum isopropoxide as an Al source; in contrast to the ubiquitous ALD precursor trimethylaluminum, dimethylaluminum isopropoxide does not degrade the zinc porphyrin dye, as confirmed by UV–vis measurements. The growth of this protective ALD layer around the dye can be monitored by an in-reactor quartz crystal microbalance (QCM). Furthermore, greater than 80% of porphyrin light absorption is retained over ∼1 month of exposure to air and light when the protective coating is present, whereas almost complete loss of porphyrin absorption is observed in less than 2 days in the absence of the ALD protective layer. Applying the Al2O3 post-treatment technique to the TiO2-adsorbed dye allows the dye to remain in electronic contact with both the semiconductor surface and a surrounding electrolyte solution, the combination of which makes this technique promising for numerous other electrochemical photovoltaic and photocatalytic applications, especially those involving the dye-sensitized evolution of oxygen.Keywords: atomic layer deposition; dimethylaluminum isopropoxide; dye enshroudment; increased dye stability; porphyrin dye; protective coating;
Co-reporter:Hasmukh A. Patel, Timur Islamoglu, Zhichang Liu, Siva Krishna Mohan Nalluri, Avik Samanta, Ommid Anamimoghadam, Christos D. Malliakas, Omar K. Farha, and J. Fraser Stoddart
Journal of the American Chemical Society August 16, 2017 Volume 139(Issue 32) pp:11020-11020
Publication Date(Web):August 3, 2017
DOI:10.1021/jacs.7b06287
Co-crystallization of K+ and Li+ ions with γ-cyclodextrin (γ-CD) has been shown to substitute the K+ ion sites partially by Li+ ions, while retaining the structural integrity and accessible porosity of CD-MOF-1 (MOF, metal–organic framework). A series of experiments, in which the K+/Li+ ratio was varied with respect to that of γ-CD, have been conducted in order to achieve the highest possible proportion of Li+ ions in the framework. Attempts to obtain a CD-MOF containing only Li+ ions resulted in nonporous materials. The structural occupancy on the part of the Li+ ions in the new CD-MOF has been confirmed by single-crystal X-ray analysis by determining the vacancies of K+-ion sites and accounting for the cation/γ-CD ratio in CD-MOF-1. The proportion of Li+ ions has also been confirmed by elemental analysis, whereas powder X-ray diffraction has established the stability of the extended framework. This noninvasive synthetic approach to generating mixed-metal CD-MOFs is a promising method for obtaining porous framework unattainable de novo. Furthermore, the CO2 and H2 capture capacities of the Li+-ion-substituted CD-MOF have been shown to exceed the highest sorption capacities reported so far for CD-MOFs.
Co-reporter:Timur Islamoglu, Subhadip Goswami, Zhanyong Li, Ashlee J. Howarth, Omar K. Farha, and Joseph T. Hupp
Accounts of Chemical Research April 18, 2017 Volume 50(Issue 4) pp:805-805
Publication Date(Web):February 8, 2017
DOI:10.1021/acs.accounts.6b00577
ConspectusMetal–organic frameworks (MOFs) are periodic, hybrid, atomically well-defined porous materials that typically form by self-assembly and consist of inorganic nodes (metal ions or clusters) and multitopic organic linkers. MOFs as a whole offer many intriguing properties, including ultrahigh porosity, tunable chemical functionality, and low density. These properties point to numerous potential applications, including gas storage, chemical separations, catalysis, light harvesting, and chemical sensing, to name a few. Reticular chemistry, or the linking of molecular building blocks into predetermined network structures, has been employed to synthesize thousands of MOFs. Given the vast library of candidate nodes and linkers, the number of potentially synthetically accessible MOFs is enormous. Nevertheless, a powerful complementary approach to obtain specific structures with desired chemical functionality is to modify known MOFs after synthesis. This approach is particularly useful when incorporation of particular chemical functionalities via direct synthesis is challenging or impossible. The challenges may stem from limited stability or solubility of precursors, unwanted secondary reactivity of precursors, or incompatibility of functional groups with the conditions needed for direct synthesis. MOFs can be postsynthetically modified by replacing the metal nodes and/or organic linkers or via functionalization of the metal nodes and/or organic linkers.Here we describe some of our efforts toward the development and application of postsynthetic strategies for imparting desired chemical functionalities in MOFs of known topology. The techniques include methods for functionalizing MOF nodes, i.e., solvent-assisted ligand incorporation (SALI) and atomic layer deposition in MOFs (AIM) as well as a method to replace structural linkers, termed solvent-assisted linker exchange (SALE), also known as postsynthethic exchange (PSE). For each functionalization strategy, we first describe its chemical basis along with the requirements for its successful implementation. We then present a small number of examples, with an emphasis on those that (a) convey the underlying concepts and/or (b) lead to functional structures (e.g., catalysts) that would be difficult or impossible to access via direct routes. The examples, however, are only illustrative, and a significant body of work exists from both our lab and others, especially for the SALE/PSE strategy. We refer readers to the papers cited and to the references therein. More exciting, in our view, will be new examples and new applications of the functionalization strategies—especially applications made possible by creatively combining the strategies. Underexplored (again, in our view) are implementations that impart electrical conductivity, enable increasingly selective chemical sensing, or facilitate cascade catalysis. It will be interesting to see where these strategies and others take this compelling field over the next few years.
Co-reporter:Timothy C. Wang, Idan Hod, Cornelius O. Audu, Nicolaas A. Vermeulen, SonBinh T. Nguyen, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces April 12, 2017 Volume 9(Issue 14) pp:12584-12584
Publication Date(Web):March 20, 2017
DOI:10.1021/acsami.6b16834
We report the design and synthesis of a metal–organic framework (MOF)–polythiophene composite that has comparable electronic conductivity to reported conductive 3-D MOFs, but with display and retention of high porosity, including mesoporosity. A robust zirconium MOF, NU-1000, was rendered electronically conductive by first incorporating, via solvent-assisted ligand incorporation (SALI), a carefully designed pentathiophene derivative at a density of one pentamer per hexa-zirconium node. Using a cast film of the intermediate composite (termed pentaSALI) on conductive glass, the incorporated oligothiophene was electrochemically polymerized to yield the conductive composite, Epoly. Depending on the doping level of the polythiophene in the composite, it can be tuned from an insulating state to a semiconduting state with conductivity of 1.3 × 10–7 (S cm–1), which is comparable to values reported for 3-D conductive MOFs. The porosity of the thin-film MOF–polythiophene composite was assessed using decane vapor uptake as determined by quartz crystal microgravimetry (QCM). The results indicate a porosity (pore volume) for Epoly essentially identical to that of bulk pentaSALI, and ∼74% of that of unmodified NU-1000. PentaSALI, and by inference Epoly, displays both micro- and mesoporosity, and features a BET surface area of nearly 1,600 m2·g–1, i.e., substantially larger than yet reported for any other electronically conductive MOF.Keywords: electronic conductivity; electropolymerization; metal−organic framework; polythiophene; QCM porosity measurement; solvent-assisted ligand incorporation;
Co-reporter:Peng Li;Nicolaas A. Vermeulen;Diego A. Gómez-Gualdrón;Ashlee J. Howarth;Christos D. Malliakas;B. Layla Mehdi;Nigel D. Browning;Alice Dohnalkova;Michael O’Keeffe
Science 2017 Volume 356(Issue 6338) pp:
Publication Date(Web):
DOI:10.1126/science.aam7851
Intricacy anchored by uranium
Metal-organic frameworks generally have one level of assembly complexity: Organic linkers join inorganic nodes in a repeating lattice. Li et al. created a structure composed of cuboctahedra, assembled from uranium cations and organic linkers, that shared triangular faces to form prisms. These structures formed cages, which in turn joined to make tetrahedra that assembled with a diamond-lattice topology. This hierarchical open structure generated a huge unit cell with more than 800 nodes and linkers, containing internal cavities with diameters of 5 and 6 nm.
Science, this issue p. 624
Co-reporter:Yangyang Liu, Ashlee J. Howarth, Nicholaas A. Vermeulen, Su-Young Moon, Joseph T. Hupp, Omar K. Farha
Coordination Chemistry Reviews 2017 Volume 346(Volume 346) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.ccr.2016.11.008
•An overview of metal-organic framework (MOF) catalysts for detoxification of chemical warfare agents (CWAs).•Hexa-zirconium(IV) building block of Zr-MOFs is catalytically active for the hydrolysis of nerve agents.•Singlet oxygen generated by photoactive MOFs selectively oxidizes sulfur mustard.•The realization of dual function MOFs for degrading two types of CWAs.Since sulfur mustard was first used in World War I, significant efforts have been made in materials and methods development for the adsorption and detoxification of different classes of chemical warfare agents (CWAs). Considering the importance of efficiency and safety in this process, catalytic degradation is a viable approach for fast and complete detoxification of CWAs. To date, a variety of catalysts have been discovered to be active for the degradation of nerve agents and sulfur mustard. Among the most promising are a class of porous functional materials named metal-organic frameworks (MOFs). In the past few years, tremendous progress has been made in this field including the discovery of zirconium MOF catalysts for fast nerve agent hydrolysis. In this review, we summarize recent advances in the development of MOF catalysts for the hydrolysis of nerve agents as well as the oxidation of sulfur mustard. Dual function MOF catalysts, i.e. catalysts that can detoxify nerve agents and sulfur mustard simultaneously, are also discussed.Download high-res image (122KB)Download full-size image
Co-reporter:J. R. Avila;A. W. Peters;Zhanyong Li;M. A. Ortuño;A. B. F. Martinson;C. J. Cramer;J. T. Hupp;O. K. Farha
Dalton Transactions 2017 vol. 46(Issue 18) pp:6128-6128
Publication Date(Web):2017/05/09
DOI:10.1039/C7DT90077E
Correction for ‘Atomic layer deposition of Cu(I) oxide films using Cu(II) bis(dimethylamino-2-propoxide) and water’ by J. R. Avila, et al., Dalton Trans., 2017, DOI: 10.1039/c6dt02572b.
Co-reporter:N. Scott Bobbitt;Matthew L. Mendonca;Ashlee J. Howarth;Timur Islamoglu;Joseph T. Hupp;Randall Q. Snurr
Chemical Society Reviews 2017 vol. 46(Issue 11) pp:3357-3385
Publication Date(Web):2017/06/06
DOI:10.1039/C7CS00108H
Owing to the vast diversity of linkers, nodes, and topologies, metal–organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal–organic frameworks.
Co-reporter:Yijun Liao;Lin Zhang;Mitchell H. Weston;William Morris;Joseph T. Hupp
Chemical Communications 2017 vol. 53(Issue 67) pp:9376-9379
Publication Date(Web):2017/08/17
DOI:10.1039/C7CC04160H
M-MOF-74s were examined for potential applications in ethylene abatement and/or storage/delivery. Due to labile binding resulting from a Jahn–Teller distortion, Cu-MOF-74 exhibits a gradual initial uptake that, in turn, translates into the highest deliverable capacity among the MOFs examined (3.6 mmol g−1). In contrast, Co-MOF-74 is the most promising candidate for ethylene abatement due to the sharp uptake at low pressure.
Co-reporter:Yijun Liao;Lin Zhang;Mitchell H. Weston;William Morris;Joseph T. Hupp
Chemical Communications 2017 vol. 53(Issue 90) pp:12244-12244
Publication Date(Web):2017/11/09
DOI:10.1039/C7CC90418E
Correction for ‘Tuning ethylene gas adsorption via metal node modulation: Cu-MOF-74 for a high ethylene deliverable capacity’ by Yijun Liao et al., Chem. Commun., 2017, 53, 9376–9379.
Co-reporter:Marek B. Majewski;Ashlee J. Howarth;Peng Li;Michael R. Wasielewski;Joseph T. Hupp
CrystEngComm (1999-Present) 2017 vol. 19(Issue 29) pp:4082-4091
Publication Date(Web):2017/07/27
DOI:10.1039/C7CE00022G
Enzymes are natural catalysts which are highly selective and efficient. Given that enzymes have very intricate and delicate structures, they need to be stabilized and protected by a support material if they are to be used under challenging catalytic conditions. This highlight focuses on the use of metal–organic frameworks as supports for enzyme encapsulation and subsequent catalytic applications. De novo and post-synthetic methods of encapsulation are discussed and the relative catalytic activities of the enzyme@MOF composites versus free enzymes are highlighted.
Co-reporter:J. R. Avila;A. W. Peters;Zhanyong Li;M. A. Ortuño;A. B. F. Martinson;C. J. Cramer;J. T. Hupp;O. K. Farha
Dalton Transactions 2017 vol. 46(Issue 18) pp:5790-5795
Publication Date(Web):2017/05/09
DOI:10.1039/C6DT02572B
To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(II), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant. Between 110 and 175 °C, a growth rate of 0.12 ± 0.02 Å per cycle was measured using an in situ quartz crystal microbalance (QCM). X-ray photoelectron spectroscopy (XPS) confirms the growth of metal–oxide films featuring Cu(I).
Co-reporter:Zhanyong Li;Aaron W. Peters;Jian Liu;Xuan Zhang;Neil M. Schweitzer;Joseph T. Hupp
Inorganic Chemistry Frontiers 2017 vol. 4(Issue 5) pp:820-824
Publication Date(Web):2017/05/16
DOI:10.1039/C7QI00056A
Ni(II) ions have been deposited on the Zr6 nodes of a metal–organic framework (MOF), UiO-66, via an ALD-like process (ALD = atomic layer deposition). By varying the number of ALD cycles, three Ni-decorated UiO-66 materials were synthesized. A suite of physical methods has been used to characterize these materials, indicating structural and high-surface-area features of the parent MOF are retained. Elemental analysis via X-ray photoelectron spectroscopy (XPS) indicates that the anchored Ni ions are mainly on surface and near-surface MOF defect sites. Upon activation, all three materials are catalytic for ethylene hydrogenation, but their catalytic activities significantly vary, with the largest clusters displaying the highest per-nickel-atom activity. The study highlights the ease and effectiveness of ALD in MOFs (AIM) for synthesizing, specifically, UiO-66-supported NiyOx catalysts.
Co-reporter:Carla F. Pereira;Ashlee J. Howarth;Nicolaas A. Vermeulen;Filipe A. Almeida Paz;João P. C. Tomé;Joseph T. Hupp
Materials Chemistry Frontiers 2017 vol. 1(Issue 6) pp:1194-1199
Publication Date(Web):2017/06/01
DOI:10.1039/C6QM00364H
Solvent-assisted linker exchange (SALE) is performed on the Zr-based metal–organic framework (MOF), UiO-66, to exchange benzene-1,4-dicarboxylate with benzene-1,4-dihydroxamate linkers. Characterization of the material before and after SALE is performed using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen adsorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The stability of the parent and daughter material is evaluated at pH 1 and 12 and the structural integrity evaluated by PXRD, mass balance and porosity measurements.
Co-reporter:Sayed Ali Akbar Razavi, Mohammad Yaser Masoomi, Timur IslamogluAli Morsali, Yan XuJoseph T. Hupp, Omar K. Farha, Jun WangPeter C. Junk
Inorganic Chemistry 2017 Volume 56(Issue 5) pp:
Publication Date(Web):February 14, 2017
DOI:10.1021/acs.inorgchem.6b02758
The rational design of functionalized porous metal–organic frameworks (MOFs) for gas adsorption applications has been applied using three spacer ligands H2DPT (3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine), DPT (3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine), and BPDH (2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) to synthesize TMU-34, [Zn(OBA)(H2DPT)0.5]n·DMF, TMU-34(−2H), [Zn(OBA)(DPT)0.5]n·DMF, and TMU-5, [Zn(OBA)(BPDH)0.5]n·1.5DMF, respectively. By controlling the pore size and chemical functionality of these three MOFs, we can improve the interactions between CO2 and especially CH4 with the frameworks. Calculated Qst(CH4) for TMU-5, TMU-34, and TMU-34(−2H) are 27, 23, and 22 kJ mol–1, respectively. These Qst values are among the highest for CH4–framework interactions. For systematic comparison, two reported frameworks, TMU-4 and TMU-5, have been compared with TMU-34 and TMU-34(−2H) in CO2 adsorption.
Co-reporter:Matthew R. DeStefanoTimur Islamoglu, Sergio J. GaribayJoseph T. Hupp, Omar K. Farha
Chemistry of Materials 2017 Volume 29(Issue 3) pp:
Publication Date(Web):January 6, 2017
DOI:10.1021/acs.chemmater.6b05115
UiO-66 is an archetypal zirconium-based metal–organic framework (MOF) that is constructed from hexanuclear zirconium oxide clusters as secondary building units (SBUs) and 1,4-benzenedicarboxylate (bdc) linkers. For the first time, a room-temperature solution-based synthesis is reported for UiO-66 and several of its derivatives, UiO-66-X (X = NH2, OH, or NO2), resulting in materials that are as porous and crystalline as those made at elevated temperatures. In addition, via modulation of the temperature at which UiO-66 is synthesized, the number of defect sites can be varied. It was found through N2 sorption isotherm analysis and potentiometric acid–base titrations that increasing the synthesis temperature from 25 to 130 °C results in a systematic decrease in the number of defect sites in UiO-66. The results suggest that, with respect to this synthetic procedure, a maximal number of defect sites is achieved [∼1.3 missing linkers per Zr6O4(OH)4(bdc)6] at a temperature of 45 °C.
Co-reporter:Martino RimoldiVarinia Bernales, Joshua Borycz, Aleksei Vjunov, Leighanne C. Gallington, Ana E. Platero-PratsI. S. Kim, John L. FultonA. B. F. Martinson, Johannes A. Lercher, Karena W. Chapman, Christopher J. Cramer, Laura GagliardiJoseph T. Hupp, Omar K. Farha
Chemistry of Materials 2017 Volume 29(Issue 3) pp:
Publication Date(Web):January 5, 2017
DOI:10.1021/acs.chemmater.6b03880
NU-1000, a zirconium-based metal–organic framework (MOF) featuring mesoporous channels, has been postsynthetically metalated via atomic layer deposition in a MOF (AIM) employing dimethylaluminum iso-propoxide ([AlMe2OiPr]2, DMAI), a milder precursor than widely used trimethylaluminum (AlMe3, TMA). The aluminum-modified NU-1000 (Al-NU-1000) has been characterized with a comprehensive suite of techniques that points to the formation of aluminum oxide clusters well dispersed through the framework and stabilized by confinement within small pores intrinsic to the NU-1000 structure. Experimental evidence allows for identification of spectroscopic similarities between Al-NU-1000 and γ-Al2O3. Density functional theory modeling provides structures and simulated spectra, the relevance of which can be assessed via comparison to experimental IR and EXAFS data. The catalytic performance of Al-NU-1000 has been benchmarked against γ-Al2O3, with promising results in terms of selectivity.
Co-reporter:Zhanyong LiAaron W. Peters, Varinia Bernales, Manuel A. Ortuño, Neil M. Schweitzer, Matthew R. DeStefano, Leighanne C. Gallington, Ana E. Platero-PratsKarena W. Chapman, Christopher J. Cramer, Laura Gagliardi, Joseph T. HuppOmar K. Farha
ACS Central Science 2017 Volume 3(Issue 1) pp:
Publication Date(Web):November 30, 2016
DOI:10.1021/acscentsci.6b00290
Zr-based metal–organic frameworks (MOFs) have been shown to be excellent catalyst supports in heterogeneous catalysis due to their exceptional stability. Additionally, their crystalline nature affords the opportunity for molecular level characterization of both the support and the catalytically active site, facilitating mechanistic investigations of the catalytic process. We describe herein the installation of Co(II) ions to the Zr6 nodes of the mesoporous MOF, NU-1000, via two distinct routes, namely, solvothermal deposition in a MOF (SIM) and atomic layer deposition in a MOF (AIM), denoted as Co-SIM+NU-1000 and Co-AIM+NU-1000, respectively. The location of the deposited Co species in the two materials is determined via difference envelope density (DED) analysis. Upon activation in a flow of O2 at 230 °C, both materials catalyze the oxidative dehydrogenation (ODH) of propane to propene under mild conditions. Catalytic activity as well as propene selectivity of these two catalysts, however, is different under the same experimental conditions due to differences in the Co species generated in these two materials upon activation as observed by in situ X-ray absorption spectroscopy. A potential reaction mechanism for the propane ODH process catalyzed by Co-SIM+NU-1000 is proposed, yielding a low activation energy barrier which is in accord with the observed catalytic activity at low temperature.
Co-reporter:Pravas Deria, Diego A. Gómez-Gualdrón, Idan Hod, Randall Q. Snurr, Joseph T. Hupp, and Omar K. Farha
Journal of the American Chemical Society 2016 Volume 138(Issue 43) pp:14449-14457
Publication Date(Web):October 21, 2016
DOI:10.1021/jacs.6b09113
Catalytic activity for acyl transfer from N-acetylimidazole (NAI) to different pyridylcarbinol (PC) regioisomers (2-PC, 3-PC, and 4-PC) is demonstrated for a set of topologically diverse, zirconium-based (porphinato)zinc metal–organic frameworks (MOFs). The MOFs studied are PCN-222, MOF-525, and NU-902, which are based on the csq, ftw, and scu topologies, respectively. The experimentally obtained reaction kinetics are discussed in light of molecular modeling results. The catalytic activity is shown to vary across the series of MOFs due to the different extent to which each topology facilitates reactant preconcentration and alignment of PC and NAI via coordination to framework porphyrin sites (orientation effects). Trends of experimental initial reaction rates with MOF topology and PC regioisomer are consistent with preconcentration effects, which depend on the number of porphyrin sites per volume of MOF, as well as with orientation effects, which depend on the number of porphyrin pairs per volume of MOF that bind PC and NAI in such a way that they are primed to form the required transition state. The present work shows how the proper alignment of catalytic linkers can enhance reaction rates in MOFs.
Co-reporter:Qishui Chen, Junling Sun, Peng Li, Idan Hod, Peyman Z. Moghadam, Zachary S. Kean, Randall Q. Snurr, Joseph T. Hupp, Omar K. Farha, and J. Fraser Stoddart
Journal of the American Chemical Society 2016 Volume 138(Issue 43) pp:14242-14245
Publication Date(Web):October 24, 2016
DOI:10.1021/jacs.6b09880
We describe the incorporation of a bistable mechanically interlocked molecule (MIM) into a robust Zr-based metal–organic framework (MOF), NU-1000, by employing a post-synthetic functionalization protocol. On average, close to two bistable [2]catenanes can be incorporated per repeating unit of the hexagonal channels of NU-1000. The reversible redox-switching of the bistable [2]catenanes is retained inside the MOF, as evidenced by solid-state UV-vis-NIR reflectance spectroscopy and cyclic voltammetry. This research demonstrates that bistable MIMs are capable of exhibiting robust dynamics inside the nanopores of a MOF.
Co-reporter:Hyunho Noh, Yuexing Cui, Aaron W. Peters, Dale R. Pahls, Manuel A. Ortuño, Nicolaas A. Vermeulen, Christopher J. Cramer, Laura Gagliardi, Joseph T. Hupp, and Omar K. Farha
Journal of the American Chemical Society 2016 Volume 138(Issue 44) pp:14720-14726
Publication Date(Web):October 25, 2016
DOI:10.1021/jacs.6b08898
Molybdenum(VI) oxide was deposited on the Zr6 node of the mesoporous metal–organic framework NU-1000 via condensed-phase deposition where the MOF is simply submerged in the precursor solution, a process named solvothermal deposition in MOFs (SIM). Exposure to oxygen leads to a monodisperse, porous heterogeneous catalyst, named Mo-SIM, and its structure on the node was elucidated both computationally and spectroscopically. The catalytic activity of Mo-SIM was tested for the epoxidation of cyclohexene. Near-quantitative yields of cyclohexene oxide and the ring-opened 1,2-cyclohexanediol were observed, indicating activity significantly higher than that of molybdenum(VI) oxide powder and comparable to that of a zirconia-supported analogue (Mo-ZrO2) prepared in a similar fashion. Despite the well-known leaching problem of supported molybdenum catalysts (i.e., loss of Mo species thus causes deactivation), Mo-SIM demonstrated no loss in the metal loading before and after catalysis, and no molybdenum was detected in the reaction mixture. In contrast, Mo-ZrO2 led to significant leaching and close to 80 wt % loss of the active species. The stability of Mo-SIM was further confirmed computationally, with density functional theory calculations indicating that the dissociation of the molybdenum(VI) species from the node of NU-1000 is endergonic, corroborating the experimental data for the Mo-SIM material.
Co-reporter:Peng Li; Su-Young Moon; Mark A. Guelta; Steven P. Harvey; Joseph T. Hupp
Journal of the American Chemical Society 2016 Volume 138(Issue 26) pp:8052-8055
Publication Date(Web):June 24, 2016
DOI:10.1021/jacs.6b03673
Immobilized enzymes typically have greater thermal and operational stability than their soluble form. Here we report that for the first time, a nerve agent detoxifying enzyme, organophosphorus acid anhydrolase (OPAA), has been successfully encapsulated into a water-stable zirconium metal–organic framework (MOF). This MOF features a hierarchical mesoporous channel structure and exhibits a 12 wt % loading capacity of OPAA. The thermal and long-term stabilities of OPAA are both significantly enhanced after immobilization.
Co-reporter:Zhanyong Li; Neil M. Schweitzer; Aaron B. League; Varinia Bernales; Aaron W. Peters; Andrew “Bean” Getsoian; Timothy C. Wang; Jeffrey T. Miller; Aleksei Vjunov; John L. Fulton; Johannes A. Lercher; Christopher J. Cramer; Laura Gagliardi; Joseph T. Hupp
Journal of the American Chemical Society 2016 Volume 138(Issue 6) pp:1977-1982
Publication Date(Web):February 2, 2016
DOI:10.1021/jacs.5b12515
Developing supported single-site catalysts is an important goal in heterogeneous catalysis since the well-defined active sites afford opportunities for detailed mechanistic studies, thereby facilitating the design of improved catalysts. We present herein a method for installing Ni ions uniformly and precisely on the node of a Zr-based metal–organic framework (MOF), NU-1000, in high density and large quantity (denoted as Ni-AIM) using atomic layer deposition (ALD) in a MOF (AIM). Ni-AIM is demonstrated to be an efficient gas-phase hydrogenation catalyst upon activation. The structure of the active sites in Ni-AIM is proposed, revealing its single-site nature. More importantly, due to the organic linker used to construct the MOF support, the Ni ions stay isolated throughout the hydrogenation catalysis, in accord with its long-term stability. A quantum chemical characterization of the catalyst and the catalytic process complements the experimental results. With validation of computational modeling protocols, we further targeted ethylene oligomerization catalysis by Ni-AIM guided by theoretical prediction. Given the generality of the AIM methodology, this emerging class of materials should prove ripe for the discovery of new catalysts for the transformation of volatile substrates.
Co-reporter:Rachel C. Klet, Timothy C. Wang, Laura E. Fernandez, Donald G. Truhlar, Joseph T. Hupp, and Omar K. Farha
Chemistry of Materials 2016 Volume 28(Issue 4) pp:1213
Publication Date(Web):February 10, 2016
DOI:10.1021/acs.chemmater.5b04887
The combination (AIM-ME) of atomic layer deposition in metal–organic frameworks (MOFs) and metal exchange (ME) is introduced as a technique to install dispersed metal atoms into the mesoporous MOF, NU-1000. Zn-AIM, which contains four Zn atoms per Zr6 node, has been synthesized through AIM and further characterized through density functional calculations to provide insight into the possible structure. Zn-AIM was then subjected to modification via transmetalation to yield uniform porous materials that present nonstructural Cu, Co, or Ni atoms.
Co-reporter:Rachel C. Klet, Yangyang Liu, Timothy C. Wang, Joseph T. Hupp and Omar K. Farha
Journal of Materials Chemistry A 2016 vol. 4(Issue 4) pp:1479-1485
Publication Date(Web):12 Jan 2016
DOI:10.1039/C5TA07687K
Potentiometric acid–base titration is introduced as a method to evaluate pKa values (Brønsted acidity) of protons present in the nodes of water stable Zr6- and Hf6-based metal–organic frameworks (MOFs), including UiO-type MOFs, NU-1000, and MOF-808. pKa values were determined for the three typical types of protons present in these MOFs: μ3-OH, M–OH2, and M–OH (M = Zr, Hf). Additionally, the data was used to quantify defect sites resulting from either a surfeit or shortage of linkers in the MOFs and to provide information about the true proton topology of each material.
Co-reporter:Subhadip Goswami, Lin Ma, Alex B. F. Martinson, Michael R. Wasielewski, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 45) pp:30863
Publication Date(Web):October 21, 2016
DOI:10.1021/acsami.6b08552
Owing to their ability to act as light-harvesting scaffolds, porphyrin-containing metal–organic frameworks (MOFs) are in the forefront of research on the application of highly ordered molecular materials to problems in solar-energy conversion. In this work, solvent-assisted linker exchange (SALE) is performed on a pillared paddlewheel porphyrin containing MOF thin film to collapse a 3D framework to a 2D framework. The change in dimensionality of the framework is confirmed by a decrease in the film thickness, the magnitude of which is in agreement with crystallographic parameters for related bulk materials. Furthermore, NMR spectroscopy performed on the digested sample suggests a similar change in geometry is achieved in bulk MOF samples. The decreased distance between the porphyrin chromophores in the 2D MOF film compared to the 3D film results in enhanced energy transfer through the film. The extent of energy transport was probed by assembling MOF thin film where the outermost layers are palladium porphyrin (P2) units, which act as energy traps and fluorescence quenchers. Steady-state emission spectroscopy together with time-resolved emission spectroscopy indicates that excitons can travel through about 9–11 layers (porphyrin layers) in 2D films, whereas in 3D films energy transfer occurs through no more than about 6–8 layers. The results are difficult to understand if only changes in MOF interlayer spacing are considered but become much more understandable if dipole–dipole coupling distances are considered.Keywords: energy transfer; fluorescence quencher; layer-by-layer; metal−organic framework; postsynthetic modification
Co-reporter:Unal Sen, Mustafa Erkartal, Chung-Wei Kung, Vijay Ramani, Joseph T. Hupp, and Omar K. Farha
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 35) pp:23015
Publication Date(Web):August 19, 2016
DOI:10.1021/acsami.6b05901
Herein, a room temperature chemical process to synthesize functional, hollow nanostructures from zeolitic imidazolate framework-8 (ZIF-8) and poly(vinylphosphonic acid) (PVPA) is reported. Syntheses are initiated by physically blending the components—a process that is accompanied first by encapsulation of ZIF-8 crystallites by PVPA and then by fragmentation of the crystallites. The fragmentation process is driven by partial displacement of the methyl-imidazolate ligands of Zn(II) in ZIF-8 by phosphonate groups on PVPA. Differences in rates of diffusion for the components of the reactive mixture yield a Kirkendall-like effect that is expressed as a hollow-particle morphology. The obtained hollow nanostructures feature hybrid shells containing PVPA, ZIF-8, and their cross-reacted products. The hybrid structures display substantial proton conductivities that increase with increasing temperature, even under the anhydrous conditions prevailing at temperatures above the boiling point of water. For example, at T = 413 K the proton conductivity of ZIF-8@PVPA reaches 3.2 (±0.12) × 10–3 S cm–1, a value comparatively higher than that for PVPA (or ZIF-8) in isolation. The high value may reflect the availability in the hybrid structures of free (and partially free), amphoteric imidazole species, and their hydrogen-bonding interactions with phosphonate and/or phosphonic acid units. The persistence of ample conductivity at high temperature reflects the elimination of phosphonic acid group dehydration and dimerization—an effect that strikingly degrades the conductivity of pure PVPA under anhydrous conditions.Keywords: fuel cell; hollow nanostructures; proton conductivity; PVPA; ZIF-8
Co-reporter:Aaron W. Peters, Zhanyong Li, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 32) pp:20675
Publication Date(Web):August 3, 2016
DOI:10.1021/acsami.6b04729
Few-atom clusters composed of nickel and sulfur have been successfully installed into the Zr(IV)-based metal–organic framework (MOF) NU-1000 via ALD-like chemistry (ALD = atomic layer deposition). X-ray photoelectron spectroscopy and Raman spectroscopy are used to determine that primarily Ni2+ and S2– sites are deposited within the MOF. In a pH 7 buffered aqueous solution, the porous catalyst is able to produce H2 gas at a rate of 3.1 mmol g–1 h–1 upon UV irradiation, whereas no H2 is generated by irradiating bare NU-1000. Upon visible light irradiation, little H2 generation was observed; however, with the addition of an organic dye, rose bengal, NiS-AIM can catalyze the production of H2 at an enhanced rate of 4.8 mmol g–1 h–1. These results indicate that ALD in MOFs (AIM) can engender reactivity within high surface area supports for applications in the solar fuels field.Keywords: atomic layer deposition; hydrogen evolution; metal−organic framework; nickel sulfide; photocatalysis
Co-reporter:Jason R. Avila, Jonathan D. Emery, Michael J. Pellin, Alex B. F. Martinson, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 31) pp:19853
Publication Date(Web):July 25, 2016
DOI:10.1021/acsami.6b05427
Examinations of enzymatic catalysts suggest one key to efficient catalytic activity is discrete size metallo clusters. Mimicking enzymatic cluster systems is synthetically challenging because conventional solution methods are prone to aggregation or require capping of the cluster, thereby limiting its catalytic activity. We introduce site-selective atomic layer deposition (ALD) on porphyrins as an alternative approach to grow isolated metal oxide islands that are spatially separated. Surface-bound tetra-acid free base porphyrins (H2TCPP) may be metalated with Mn using conventional ALD precursor exposure to induce homogeneous hydroxide synthetic handles which acts as a nucleation point for subsequent ALD MnO island growth. Analytical fitting of in situ QCM mass uptake reveals island growth to be hemispherical with a convergence radius of 1.74 nm. This growth mode is confirmed with synchrotron grazing-incidence small-angle X-ray scattering (GISAXS) measurements. Finally, we extend this approach to other ALD chemistries to demonstrate the generality of this route to discrete metallo island materials.Keywords: atomic layer deposition; grazing incident small angle scattering; island nucleation; manganese oxide; porphyrin; quartz crystal microbalance; vapor metalation
Co-reporter:Idan Hod, Omar K. Farha and Joseph T. Hupp
Chemical Communications 2016 vol. 52(Issue 8) pp:1705-1708
Publication Date(Web):15 Dec 2015
DOI:10.1039/C5CC09695B
Herein we demonstrate the use of host–guest chemistry to modulate rates of charge transport in metal–organic framework (MOF) films. The kinetics of site-to-site of charge hopping and, in turn, the overall redox conductivity, of a ferrocene-modified MOF can be altered by up to 30-fold by coupling electron exchange to the oxidation-state-dependent formation of inclusion complexes between cyclodextrin and channel-tethered metallocenes.
Co-reporter:Yangyang Liu, Rachel C. Klet, Joseph T. Hupp and Omar Farha
Chemical Communications 2016 vol. 52(Issue 50) pp:7806-7809
Publication Date(Web):19 May 2016
DOI:10.1039/C6CC03727E
Seven Zr/Hf-based MOFs with different degrees of defects were obtained by modulating the synthetic conditions. The number of missing linkers in these MOFs was calculated based on potentiometric acid–base titration. The number of defects was found to correlate quantitatively with the catalytic activity of UiO-type MOFs for an acid-catalyzed epoxide ring-opening reaction. More importantly, we were able to identify a MOF with inherent defective Zr6 nodes, which showed great activity and regio-selectivity for the epoxide ring-opening reaction.
Co-reporter:Mizuho Yabushita, Peng Li, Varinia Bernales, Hirokazu Kobayashi, Atsushi Fukuoka, Laura Gagliardi, Omar K. Farha and Alexander Katz
Chemical Communications 2016 vol. 52(Issue 44) pp:7094-7097
Publication Date(Web):03 May 2016
DOI:10.1039/C6CC03266D
Metal–organic framework (MOF) material NU-1000 adsorbs dimers cellobiose and lactose from aqueous solution, in amounts exceeding 1250 mg gNU-1000−1 while completely excluding the adsorption of the monomer glucose, even in a competitive mode with cellobiose. The MOF also discriminates between dimers consisting of α and β linkages, showing no adsorption of maltose. Electronic structure calculations demonstrate that key to this selective molecular recognition is the number of favorable CH–π interactions made by the sugar with pyrene units of the MOF.
Co-reporter:Krunoslav Užarević, Timothy C. Wang, Su-Young Moon, Athena M. Fidelli, Joseph T. Hupp, Omar K. Farha and Tomislav Friščić
Chemical Communications 2016 vol. 52(Issue 10) pp:2133-2136
Publication Date(Web):08 Dec 2015
DOI:10.1039/C5CC08972G
We develop the first mechanochemical and solvent-free routes for zirconium metal–organic frameworks, making the frameworks UiO-66 and UiO-66-NH2 accessible on the gram scale without strong acids, high temperatures or excess reactants. The frameworks form either by milling, or spontaneous self-assembly by simply exposing solid mixtures of reactants to organic vapour. The generated frameworks exhibit high porosity and catalytic activity in the hydrolysis of model nerve agents, on par with their solvothermally generated counterparts.
Co-reporter:Hea Jung Park, Monica C. So, David Gosztola, Gary P. Wiederrecht, Jonathan D. Emery, Alex B. F. Martinson, Süleyman Er, Christopher E. Wilmer, Nicolaas A. Vermeulen, Alán Aspuru-Guzik, J. Fraser Stoddart, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 38) pp:24983
Publication Date(Web):September 12, 2016
DOI:10.1021/acsami.6b03307
We demonstrate that thin films of metal–organic framework (MOF)-like materials, containing two perylenediimides (PDICl4, PDIOPh2) and a squaraine dye (S1), can be fabricated by layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400–750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (PDICl4 and PDIOPh2) and acceptor (S1) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films. These findings have significant implications for the development of solar energy conversion devices based on MOFs.Keywords: directional energy transfer; energy cascade; exciton migration; layer-by-Layer; multizone MOF-like film
Co-reporter:Su-Young Moon, Ashlee J. Howarth, Timothy Wang, Nicolaas A. Vermeulen, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2016 vol. 52(Issue 16) pp:3438-3441
Publication Date(Web):28 Jan 2016
DOI:10.1039/C5CC10384C
A halochromic Zr6-based metal–organic framework is synthesized using solvent-assisted linker incorporation (SALI) with NU-1000 as a platform and carboxylnaphthofluorescein as a pH sensitive ligand. The functionalized MOF can catalytically detoxify nerve agent simulants in addition to visually detecting the acidic byproduct produced during detoxification.
Co-reporter:Paul W. Siu, John P. Siegfried, Mitchell H. Weston, Patrick E. Fuller, William Morris, Christopher R. Murdock, William J. Hoover, Rachelle K. Richardson, Stephanie Rodriguez, and Omar K. Farha
Inorganic Chemistry 2016 Volume 55(Issue 23) pp:12110-12113
Publication Date(Web):November 17, 2016
DOI:10.1021/acs.inorgchem.6b02273
Coordinatively unsaturated metal–organic frameworks (MOFs) were studied for boron trifluoride (BF3) sorption. MOF-74-Mg, MOF-74-Mn, and MOF-74-Co show high initial uptake (below 6.7 × 10–3 bar) with negligible deliverable capacity. The BF3 isotherm of MOF-74-Cu exhibits gradual uptake up to 0.9 bar and has a deliverable gravimetric capacity that is more than 100% higher than activated carbon. Two other Cu2+ MOFs, MOF-505 and HKUST-1, have slightly lower deliverable capacities compared to MOF-74-Cu.
Co-reporter:Casey J. Stephenson, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2016 Volume 55(Issue 4) pp:1361-1363
Publication Date(Web):January 29, 2016
DOI:10.1021/acs.inorgchem.5b02880
2-Methylimidazolate linkers of Pt@ZIF-8 are exchanged with imidazolate using solvent-assisted linker exchange (SALE) to expand the apertures of the parent material and create Pt@SALEM-2. Characterization of the material before and after SALE was performed. Both materials are active as catalysts for the hydrogenation of 1-octene, whereas the hydrogenation of cis-cyclohexene occurred only with Pt@SALEM-2, consistent with larger apertures for the daughter material. The largest substrate, β-pinene, proved to be unreactive with H2 when either material was employed as a candidate catalyst, supporting the contention that substrate molecules, for both composites, must traverse the metal–organic framework component in order to reach the catalytic nanoparticles.
Co-reporter:Sol Ahn, Nicholas E. Thornburg, Zhanyong Li, Timothy C. Wang, Leighanne C. Gallington, Karena W. Chapman, Justin M. Notestein, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2016 Volume 55(Issue 22) pp:11954
Publication Date(Web):October 31, 2016
DOI:10.1021/acs.inorgchem.6b02103
Developing structurally well-defined, supported oxide catalysts remains a significant challenge. Here, we report the grafting of Nb(V) oxide sites onto the nodes of the Zr-based metal organic framework (MOF) NU-1000 as a stable, well-defined catalyst support. Nb(V) oxide was deposited with loadings up to 1.6 mmol/g via two postsynthetic methods: atomic layer deposition in a MOF, and solution-phase grafting in a MOF. Difference envelope density measurements indicated that the two synthetic methods resulted in different local structures of the Nb(V) ions within NU-1000. Despite their high Nb(V) loadings, which were equivalent to >60% surface coverage, nearly all Nb(V) sites of the MOF-supported catalysts were active sites for alkene epoxidation, as confirmed by phenylphosphonic acid titration. The MOF-supported catalysts were more selective than the control Nb-ZrO2 catalyst for cyclohexene epoxidation with aqueous H2O2 and were far more active on a gravimetric basis.
Co-reporter:Ashlee J. Howarth, Timothy C. Wang, Salih S. Al-Juaid, Saadullah G. Aziz, Joseph T. Hupp and Omar K. Farha
Dalton Transactions 2016 vol. 45(Issue 1) pp:93-97
Publication Date(Web):18 Nov 2015
DOI:10.1039/C5DT04163E
A Zr-based MOF, NU-1000, comprised of Zr6 nodes and tetratopic pyrene-containing linkers is studied for adsorption and extraction of SO42− from water. The adsorption capacity and uptake time of SO42− in NU-1000 is determined at varying concentrations to give an overall maximum adsorption capacity of 56 mg SO42− per g of MOF. Selective adsorption of SO42− by NU-1000 in the presence of other anions as well as regeneration of the sorbent is also explored.
Co-reporter:Michael J. Katz, Ashlee J. Howarth, Peyman Z. Moghadam, Jared B. DeCoste, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Dalton Transactions 2016 vol. 45(Issue 10) pp:4150-4153
Publication Date(Web):24 Sep 2015
DOI:10.1039/C5DT03436A
Cu-MOF-74 (also known as Cu-CPO-27) was identified as a sorbent having one of the highest densities of Cu(II) sites per unit volume. Given that Cu(II) in the framework can be thermally activated to yield a five-coordinate Cu(II) species, we identified this MOF as a potential candidate for maximal volumetric uptake of ammonia. To that end, the kinetic breakthrough of ammonia in Cu-MOF-74/Cu-CPO-27 was examined under both dry and humid conditions. Under dry conditions the MOF exhibited a respectable performance (2.6 vs. 2.9 NH3 per nm3 for the current record holder HKUST-1), and under 80% relative humidity, the MOF outperformed HKUST-1 (5.9 vs. 3.9 NH3 per nm3, respectively).
Co-reporter:Yan Xu, Ashlee J. Howarth, Timur Islamoglu, Cleiser T. da Silva, Joseph T. Hupp, Omar K. Farha
Inorganic Chemistry Communications 2016 Volume 67() pp:60-63
Publication Date(Web):May 2016
DOI:10.1016/j.inoche.2016.03.002
•A non-catenated nickel (II) pillared paddlewheel metal-organic framework is prepared;•The combination of solvent-assisted linker exchange and transmetallation is applied;•The Ni(II)-based metal-organic framework appears to be unattainable de novo;•Ni(II)-MOF has enhanced N2 uptake compared to its isostructural Zn(II) analogue.A non-catenated nickel (II) pillared paddlewheel metal-organic framework is synthesized through a combination of solvent-assisted linker exchange and transmetallation. Compared to its isostructural Zn(II) analogue, the nickel (II) pillared paddlewheel metal-organic framework features an enhanced N2 sorption performance. It is notable that the nickel (II)-based metal-organic framework could not (in our hands) be synthesized de novo. The experimental results validate that multiple building-block-replacement (BBR) methods can be utilized to access materials that are challenging to synthesize directly.A new non-catenated nickel (II) pillar-layer metal-organic framework is achieved through the combination of solvent-assisted linker exchange (SALE) and transmetallation.
Co-reporter:Peng Li, Su-Young Moon, Mark A. Guelta, Lu Lin, Diego A. Gómez-Gualdrón, Randall Q. Snurr, Steven P. Harvey, Joseph T. Hupp, and Omar K. Farha
ACS Nano 2016 Volume 10(Issue 10) pp:9174
Publication Date(Web):October 5, 2016
DOI:10.1021/acsnano.6b04996
We report the synthesis and characterization of a water-stable zirconium metal–organic framework (MOF), NU-1003, featuring the largest mesoporous aperture known for a zirconium MOF. This material has been used to immobilize the nerve agent hydrolyzing enzyme, organophosphorus acid anhydrolase (OPAA). The catalytic efficiency of immobilized OPAA in nanosized NU-1003 is significantly increased compared to that of OPAA immobilized in microsized NU-1003 and even exceeds that of the free OPAA enzyme. This paper highlights a method for rapid and highly efficient hydrolysis of nerve agents using nanosized enzyme carriers.Keywords: enzyme immobilization; metal−organic framework; nanocarrier; nerve agent catalysis
Co-reporter:Yasemin Çimen, Aaron W. Peters, Jason R. Avila, William L. Hoffeditz, Subhadip Goswami, Omar K. Farha, and Joseph T. Hupp
Langmuir 2016 Volume 32(Issue 46) pp:12005-12012
Publication Date(Web):November 7, 2016
DOI:10.1021/acs.langmuir.6b02699
Transition metal sulfides show great promise for applications ranging from catalysis to electrocatalysis to photovoltaics due to their high stability and conductivity. Nickel sulfide, particularly known for its ability to electrochemically reduce protons to hydrogen gas nearly as efficiently as expensive noble metals, can be challenging to produce with certain surface site compositions or morphologies, e.g., conformal thin films. To this end, we employed atomic layer deposition (ALD), a preeminent method to fabricate uniform and conformal films, to construct thin films of nickel sulfide (NiSx) using bis(N,N′-di-tert-butylacetamidinato)nickel(II) (Ni(amd)2) vapor and hydrogen sulfide gas. Effects of experimental conditions such as pulse and purge times and temperature on the growth of NiSx were investigated. These revealed a wide temperature range, 125–225 °C, over which self-limiting NiSx growth can be observed. In situ quartz crystal microbalance (QCM) studies revealed conventional linear growth behavior for NiSx films, with a growth rate of 9.3 ng/cm2 per cycle being obtained. The ALD-synthesized films were characterized using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) methods. To assess the electrocatalyitic activity of NiSx for evolution of molecular hydrogen, films were grown on conductive-glass supports. Overpotentials at a current density of 10 mA/cm2 were recorded in both acidic and pH 7 phosphate buffer aqueous reaction media and found to be 440 and 576 mV, respectively, with very low NiSx loading. These results hint at the promise of ALD-grown NiSx materials as water-compatible electrocatalysts.
Co-reporter:Dr. M. Hassan Beyzavi;Dr. Nicolaas A. Vermeulen;Dr. Kainan Zhang; Monica So;Chung-Wei Kung; Joseph T. Hupp; Omar K. Farha
ChemPlusChem 2016 Volume 81( Issue 8) pp:708-713
Publication Date(Web):
DOI:10.1002/cplu.201600046
Abstract
A functional metal–organic framework (MOF) composed of robust porphyrinic material (RPM) based on the pillared-paddlewheel topology is prepared with large 3 D channels, and is used to perform a tandem epoxidation/CO2 insertion reaction. The designated system benefits from two metalloporphyrins: 1) a Mn-porphyrin, which catalyzes the epoxidation of an olefin substrate, and 2) a Zn-porphyrin, which catalyzes the epoxide opening. By using an automated liquid-phase epitaxial growth system, the RPM-MOF is also prepared in layer-by-layer fashion as an ultrathin film on a self-assembled-monolayer-coated silicon platform. Deployed as a tandem catalyst, the film version yields a substantially higher catalytic turnover number for tandem methoxy-styrene epoxidation followed by CO2 insertion than the bulk crystalline MOF samples.
Co-reporter:Rachel C. Klet; Samat Tussupbayev; Joshua Borycz; James R. Gallagher; Madelyn M. Stalzer; Jeffrey T. Miller; Laura Gagliardi; Joseph T. Hupp; Tobin J. Marks; Christopher J. Cramer; Massimiliano Delferro
Journal of the American Chemical Society 2015 Volume 137(Issue 50) pp:15680-15683
Publication Date(Web):December 14, 2015
DOI:10.1021/jacs.5b11350
A structurally well-defined mesoporous Hf-based metal–organic framework (Hf-NU-1000) is employed as a well-defined scaffold for a highly electrophilic single-site d0 Zr–benzyl catalytic center. This new material Hf-NU-1000-ZrBn is fully characterized by a variety of spectroscopic techniques and DFT computation. Hf-NU-1000-ZrBn is found to be a promising single-component catalyst (i.e., not requiring a catalyst/activator) for ethylene and stereoregular 1-hexene polymerization.
Co-reporter:M. Hassan Beyzavi; Nicolaas A. Vermeulen; Ashlee J. Howarth; Samat Tussupbayev; Aaron B. League; Neil M. Schweitzer; James R. Gallagher; Ana E. Platero-Prats; Nema Hafezi; Amy A. Sarjeant; Jeffrey T. Miller; Karena W. Chapman; J. Fraser Stoddart; Christopher J. Cramer; Joseph T. Hupp
Journal of the American Chemical Society 2015 Volume 137(Issue 42) pp:13624-13631
Publication Date(Web):October 4, 2015
DOI:10.1021/jacs.5b08440
Tandem catalytic systems, often inspired by biological systems, offer many advantages in the formation of highly functionalized small molecules. Herein, a new metal–organic framework (MOF) with porphyrinic struts and Hf6 nodes is reported. This MOF demonstrates catalytic efficacy in the tandem oxidation and functionalization of styrene utilizing molecular oxygen as a terminal oxidant. The product, a protected 1,2-aminoalcohol, is formed selectively and with high efficiency using this recyclable heterogeneous catalyst. Significantly, the unusual regioselective transformation occurs only when an Fe-decorated Hf6 node and the Fe–porphyrin strut work in concert. This report is an example of concurrent orthogonal tandem catalysis.
Co-reporter:Pravas Deria; Diego A. Gómez-Gualdrón; Wojciech Bury; Herbert T. Schaef; Timothy C. Wang; Praveen K. Thallapally; Amy A. Sarjeant; Randall Q. Snurr; Joseph T. Hupp
Journal of the American Chemical Society 2015 Volume 137(Issue 40) pp:13183-13190
Publication Date(Web):September 20, 2015
DOI:10.1021/jacs.5b08860
“Breathing” metal–organic frameworks (MOFs) are an emerging class of soft porous crystals (SPCs) with potential for high working capacity for gas storage applications. However, most breathing MOFs have low stability and/or low surface area. Here we report a water-stable, high surface area, breathing MOF of ftw topology, NU-1105. While Zr6-oxo clusters as nodes introduce water stability in NU-1105, its high surface area and breathing character stem from its pyrene-based tetracarboxylate (Py-FP) linkers, in which the fluorene units (F) in the FP “arms” play a key role in promoting breathing behavior. During gas sorption studies, the “closed pore” (cp) ↔ “open pore” (op) transition of NU-1105 occurs at a propane pressure of ∼3 bar. At 1 bar, NU-1105 is in its cp form and adsorbs less propane than it would in its op form, highlighting improved working capacity. In situ powder X-ray diffraction during propane sorption was used to track the cp ↔ op transition, and molecular modeling was used to elucidate the structure of the op and cp forms of NU-1105. According to TD-DFT calculations, the proposed conformations of the Py-FP linkers in the op and cp forms are consistent with the measured excitation and emission spectra of the op and cp forms of NU-1105. Similar structural transitions are also observed in the porphyrinic MOF NU-1104 depending on the identity of the porphyrin core; we observed breathing behavior if the constituent Por-PTP linker is nonmetalated.
Co-reporter:Ashlee J. Howarth; Michael J. Katz; Timothy C. Wang; Ana E. Platero-Prats; Karena W. Chapman; Joseph T. Hupp
Journal of the American Chemical Society 2015 Volume 137(Issue 23) pp:7488-7494
Publication Date(Web):May 22, 2015
DOI:10.1021/jacs.5b03904
A series of zirconium-based, metal–organic frameworks (MOFs) were tested for their ability to adsorb and remove selenate and selenite anions from aqueous solutions. MOFs were tested for adsorption capacity and uptake time at different concentrations. NU-1000 was shown to have the highest adsorption capacity, and fastest uptake rates for both selenate and selenite, of all zirconium-based MOFs studied here. Herein, the mechanism of selenate and selenite adsorption on NU-1000 is explored to determine the important features that make NU-1000 a superior adsorbent for this application.
Co-reporter:C. Michael McGuirk; Michael J. Katz; Charlotte L. Stern; Amy A. Sarjeant; Joseph T. Hupp; Omar K. Farha;Chad A. Mirkin
Journal of the American Chemical Society 2015 Volume 137(Issue 2) pp:919-925
Publication Date(Web):January 9, 2015
DOI:10.1021/ja511403t
Herein, we demonstrate that the incorporation of an acidic hydrogen-bond-donating squaramide moiety into a porous UiO-67 metal–organic framework (MOF) derivative leads to dramatic acceleration of the biorelevant Friedel–Crafts reaction between indole and β-nitrostyrene. In comparison, it is shown that free squaramide derivatives, not incorporated into MOF architectures, have no catalytic activity. Additionally, using the UiO-67 template, we were able to perform a direct comparison of catalytic activity with that of the less acidic urea-based analogue. This is the first demonstration of the functionalization of a heterogeneous framework with an acidic squaramide derivative.
Co-reporter:Michael J. Katz, Rachel C. Klet, Su-Young Moon, Joseph E. Mondloch, Joseph T. Hupp, and Omar K. Farha
ACS Catalysis 2015 Volume 5(Issue 8) pp:4637
Publication Date(Web):June 26, 2015
DOI:10.1021/acscatal.5b00785
The rapid destruction of chemical threats, such as phosphate-based nerve agents, is of considerable current interest. The hydrolysis of the nerve-agent simulant methylparaoxon, as catalyzed by UiO-66 and UiO-67, was examined as a function of pH. Surprisingly, even though typical phosphate–ester hydrolysis mechanisms entail nucleophilic attack of the simulant by aqueous hydroxide, the rate of hydrolysis accelerates as the solution pH is lowered. The unexpected behavior is attributed to a pH-dependent composition change followed by ligand substitution at the Zr6-based node.Keywords: defects; hydrolysis; metal−organic frameworks; pH; phosphate nerve agents; UiO
Co-reporter:Michael J. Katz, Su-Young Moon, Joseph E. Mondloch, M. Hassan Beyzavi, Casey J. Stephenson, Joseph T. Hupp and Omar K. Farha
Chemical Science 2015 vol. 6(Issue 4) pp:2286-2291
Publication Date(Web):24 Feb 2015
DOI:10.1039/C4SC03613A
The hydrolysis of nerve agents is of primary concern due to the severe toxicity of these agents. Using a MOF-based catalyst (UiO-66), we have previously demonstrated that the hydrolysis can occur with relatively fast half-lives of 50 minutes. However, these rates are still prohibitively slow to be efficiently utilized for some practical applications (e.g., decontamination wipes used to clean exposed clothing/skin/vehicles). We thus turned our attention to derivatives of UiO-66 in order to probe the importance of functional groups on the hydrolysis rate. Three UiO-66 derivatives were explored; UiO-66-NO2 and UiO-66-(OH)2 showed little to no change in hydrolysis rate. However, UiO-66-NH2 showed a 20 fold increase in hydrolysis rate over the parent UiO-66 MOF. Half-lives of 1 minute were observed with this MOF. In order to probe the role of the amino moiety, we turned our attention to UiO-67, UiO-67-NMe2 and UiO-67-NH2. In these MOFs, the amino moiety is in close proximity to the zirconium node. We observed that UiO-67-NH2 is a faster catalyst than UiO-67 and UiO-67-NMe2. We conclude that the role of the amino moiety is to act as a proton-transfer agent during the catalytic cycle and not to hydrogen bond or to form a phosphorane intermediate.
Co-reporter:Pravas Deria, Yongchul G. Chung, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Science 2015 vol. 6(Issue 9) pp:5172-5176
Publication Date(Web):01 Jul 2015
DOI:10.1039/C5SC01784J
Water stability in metal–organic frameworks (MOFs) is critical for several practical applications. While water instability is mainly thought to stem from linker hydrolysis, MOFs with strong, hydrolysis-resistant metal-linker bonds can be susceptible to damage by capillary forces, which cause cavities and channels to collapse during activation from water. This study utilizes metal node functionalization as a strategy to create vapor-stable and recyclable MOFs.
Co-reporter:Idan Hod, Matthew D. Sampson, Pravas Deria, Clifford P. Kubiak, Omar K. Farha, and Joseph T. Hupp
ACS Catalysis 2015 Volume 5(Issue 11) pp:6302
Publication Date(Web):September 18, 2015
DOI:10.1021/acscatal.5b01767
Realization of heterogeneous electrochemical CO2-to-fuel conversion via molecular catalysis under high-flux conditions requires the assembly of large quantities of reactant-accessible catalysts on conductive surfaces. As a proof of principle, we demonstrate that electrophoretic deposition of thin films of an appropriately chosen metal–organic framework (MOF) material is an effective method for immobilizing the needed quantity of catalyst. For electrocatalytic CO2 reduction, we used a material that contains functionalized Fe-porphyrins as catalytically competent, redox-conductive linkers. The approach yields a high effective surface coverage of electrochemically addressable catalytic sites (∼1015 sites/cm2). The chemical products of the reduction, obtained with ∼100% Faradaic efficiency, are mixtures of CO and H2. These results validate the strategy of using MOF chemistry to obtain porous, electrode-immobilized, networks of molecular catalysts having competency for energy-relevant electrochemical reactions.Keywords: CO2 reduction; electrocatalysis; Fe-porphyrin; metal organic frameworks; redox conductivity; solar fuel
Co-reporter:Sherzod T. Madrahimov, James R. Gallagher, Guanghui Zhang, Zachary Meinhart, Sergio J. Garibay, Massimiliano Delferro, Jeffrey T. Miller, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
ACS Catalysis 2015 Volume 5(Issue 11) pp:6713
Publication Date(Web):September 23, 2015
DOI:10.1021/acscatal.5b01604
NU-1000-(bpy)NiII, a highly porous MOF material possessing well-defined (bpy)NiII moieties, was prepared through solvent-assisted ligand incorporation (SALI). Treatment with Et2AlCl affords a single-site catalyst with excellent catalytic activity for ethylene dimerization (intrinsic activity for butenes that is up to an order of magnitude higher than the corresponding (bpy)NiCl2 homogeneous analogue) and stability (can be reused at least three times). The high porosity of this catalyst results in outstanding levels of activity at ambient temperature in gas-phase ethylene dimerization reactions, both under batch and continuous flow conditions.Keywords: (bipyridyl)nickel complexes; catalysis; ethylene dimerization; gas-phase reaction; metal−organic framework
Co-reporter:Kainan Zhang, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
ACS Catalysis 2015 Volume 5(Issue 8) pp:4859
Publication Date(Web):July 10, 2015
DOI:10.1021/acscatal.5b01388
A series of porphyrin-based porous organic polymers (PPOPs) were synthesized in excellent yields via the Yamamoto–Ullmann couplings of tetrabromo spirobifluorene with several brominated porphyrin monomers. After isolation and demetalation, the metal-free PPOP can be postsynthetically metalated to form a MnIII–PPOP that is catalytically active toward the selective double-epoxidation of divinylbenzene to divinylbenzene dioxide.Keywords: divinylbenzene; divinylbenzene dioxide; epoxidation; Mn(porphyrin); porous organic polymer
Co-reporter:Chung-Wei Kung, Joseph E. Mondloch, Timothy C. Wang, Wojciech Bury, William Hoffeditz, Benjamin M. Klahr, Rachel C. Klet, Michael J. Pellin, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 51) pp:28223
Publication Date(Web):December 4, 2015
DOI:10.1021/acsami.5b06901
Thin films of the metal–organic framework (MOF) NU-1000 were grown on conducting glass substrates. The films uniformly cover the conducting glass substrates and are composed of free-standing sub-micrometer rods. Subsequently, atomic layer deposition (ALD) was utilized to deposit Co2+ ions throughout the entire MOF film via self-limiting surface-mediated reaction chemistry. The Co ions bind at aqua and hydroxo sites lining the channels of NU-1000, resulting in three-dimensional arrays of separated Co ions in the MOF thin film. The Co-modified MOF thin films demonstrate promising electrocatalytic activity for water oxidation.Keywords: atomic layer deposition; cobalt oxide; electrocatalyst; metal−organic frameworks; pyrene; water oxidation
Co-reporter:Jason R. Avila, Dong Wook Kim, Martino Rimoldi, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 30) pp:16138
Publication Date(Web):July 20, 2015
DOI:10.1021/acsami.5b04043
Atomic layer deposition (ALD) has been shown to be an excellent method for depositing thin films of iron oxide. With limited iron precursors available, the methods widely used require harsh conditions such as high temperatures and/or the use of oxidants such as ozone or peroxide. This letter aims to show that bis(N,N′-di-t-butylacetamidinato) iron(II) (iron bisamidinate or FeAMD) is an ideal ALD precursor because of its reactivity with water and relative volatility. Using in situ QCM analysis, we show outstanding conformal self-limiting growth of FeOx using FeAMD and water at temperatures lower than 200 °C. By annealing thin films of FeOx at 500 °C, we observe the formation of α-Fe2O3, confirming that we can use FeAMD to fabricate thin films of catalytically promising iron oxide materials using moderate growth conditions.Keywords: atomic layer deposition; hematite; in situ; iron bisamidinate; iron oxide; quartz crystal microbalance
Co-reporter:Monica C. So, M. Hassan Beyzavi, Rohan Sawhney, Osama Shekhah, Mohamed Eddaoudi, Salih S. Al-Juaid, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 vol. 51(Issue 1) pp:85-88
Publication Date(Web):17 Oct 2014
DOI:10.1039/C4CC05727A
Herein, we demonstrate the robustness of layer-by-layer (LbL)-assembled, pillared-paddlewheel-type MOF films toward conversion to new or modified MOFs via solvent-assisted linker exchange (SALE) and post-assembly linker metalation. Further, we show that LbL synthesis can afford MOFs that have proven inaccessible through other de novo strategies.
Co-reporter:Monica C. So, Gary P. Wiederrecht, Joseph E. Mondloch, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 vol. 51(Issue 17) pp:3501-3510
Publication Date(Web):12 Jan 2015
DOI:10.1039/C4CC09596K
A critical review of the emerging field of MOFs for photon collection and subsequent energy transfer is presented. Discussed are examples involving MOFs for (a) light harvesting, using (i) MOF-quantum dots and molecular chromophores, (ii) chromophoric MOFs, and (iii) MOFs with light-harvesting properties, and (b) energy transfer, specifically via the (i) Förster energy transfer and (ii) Dexter exchange mechanism.
Co-reporter:Peng Li, Rachel C. Klet, Su-Young Moon, Timothy C. Wang, Pravas Deria, Aaron W. Peters, Benjamin M. Klahr, Hea-Jung Park, Salih S. Al-Juaid, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 vol. 51(Issue 54) pp:10925-10928
Publication Date(Web):11 Jun 2015
DOI:10.1039/C5CC03398E
The synthesis of nano-sized particles of NU-1000 (length from 75 nm to 1200 nm) and PCN-222/MOF-545 (length from 350 nm to 900 nm) is reported. The catalytic hydrolysis of methyl paraoxon was investigated as a function of NU-1000 crystallite size and a significant enhancement in the rate was observed for the nano-sized crystals compared to microcrystals.
Co-reporter:Pravas Deria, Song Li, Hongda Zhang, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 vol. 51(Issue 62) pp:12478-12481
Publication Date(Web):06 Jul 2015
DOI:10.1039/C5CC04808G
CO2 capture is essential for reducing the carbon footprint of coal-fired power plants. Here we show, both experimentally and computationally, a new design strategy for capturing CO2 in nanoporous adsorbents. The approach involves ‘complementary organic motifs’ (COMs), which have a precise alignment of charge densities that is complementary to the CO2 quadrupole. Two promising COMs were post-synthetically incorporated into a robust metal–organic framework (MOF) material using solvent-assisted ligand incorporation (SALI). We demonstrate that these COM-functionalized MOFs exhibit high capacity and selectivity for CO2 relative to other reported motifs.
Co-reporter:Su-Young Moon; George W. Wagner; Joseph E. Mondloch; Gregory W. Peterson; Jared B. DeCoste; Joseph T. Hupp
Inorganic Chemistry 2015 Volume 54(Issue 22) pp:10829-10833
Publication Date(Web):October 27, 2015
DOI:10.1021/acs.inorgchem.5b01813
The nerve agent VX is among the most toxic chemicals known to mankind, and robust solutions are needed to rapidly and selectively deactivate it. Herein, we demonstrate that three Zr6-based metal–organic frameworks (MOFs), namely, UiO-67, UiO-67-NH2, and UiO-67-N(Me)2, are selective and highly active catalysts for the hydrolysis of VX. Utilizing UiO-67, UiO-67-NH2, and UiO-67-N(Me)2 in a pH 10 buffered solution of N-ethylmorpholine, selective hydrolysis of the P–S bond in VX was observed. In addition, UiO-67-N(Me)2 was found to catalyze VX hydrolysis with an initial half-life of 1.8 min. This half-life is nearly 3 orders of magnitude shorter than that of the only other MOF tested to date for hydrolysis of VX and rivals the activity of the best nonenzymatic materials. Hydrolysis utilizing Zr-based MOFs is also selective and facile in the absence of pH 10 buffer (just water) and for the destruction of the toxic byproduct EA-2192.
Co-reporter:Marianne B. Lalonde; Joseph E. Mondloch; Pravas Deria; Amy A. Sarjeant; Salih S. Al-Juaid; Osman I. Osman; Omar K. Farha;Joseph T. Hupp
Inorganic Chemistry 2015 Volume 54(Issue 15) pp:7142-7144
Publication Date(Web):July 20, 2015
DOI:10.1021/acs.inorgchem.5b01231
Solvent-assisted linker exchange (SALE) has recently emerged as an attractive strategy for the synthesis of metal–organic frameworks (MOFs) that are unobtainable via traditional synthetic pathways. Herein we present the first example of selective SALE in which only the benzimiadazolate-containing linkers in a series of mixed-linker zeolitic imidazolate frameworks (ZIF-69, -78, and -76) are replaced. The resultant materials (SALEM-10, SALEM-10b, and SALEM-11, respectively) are isostructural to the parent framework and in each case contain trifluoromethyl moieties. We therefore evaluated each of these materials for their hydrophobicity in condensed and gas phases. We expect that selective SALE will significantly facilitate the design of improved, and potentially complex, MOF materials with new and unusual properties.
Co-reporter:Pravas Deria, Wojciech Bury, Idan Hod, Chung-Wei Kung, Olga Karagiaridi, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2015 Volume 54(Issue 5) pp:2185-2192
Publication Date(Web):February 9, 2015
DOI:10.1021/ic502639v
Solvent-assisted ligand incorporation (SALI) is useful for functionalizing the channels of metal–organic framework (MOF) materials such as NU-1000 that offer substitutionally labile zirconium(IV) coordination sites for nonbridging ligands. Each of the 30 or so previous examples relied upon coordination of a carboxylate ligand to achieve incorporation. Here we show that, with appropriate attention to ligand/node stoichiometry, SALI can also be achieved with phosphonate-terminated ligands. Consistent with stronger M(IV) coordination of phosphonates versus carboxylates, this change extends the pH range for retention of incorporated ligands. The difference in coordination strength can be exploited to achieve stepwise incorporation of pairs of ligands—specifically, phosphonates species followed by carboxylate species—without danger of displacement of the first ligand type by the second. Diffuse reflectance infrared Fourier-transform spectroscopy suggests that the phosphonate ligands are connected to the MOF node as RPO2(OH)¯ species in a moiety that leaves a base-accessible −OH moiety on each bound phosphonate.
Co-reporter:Olga Karagiaridi, Nicolaas A. Vermeulen, Rachel C. Klet, Timothy C. Wang, Peyman Z. Moghadam, Salih S. Al-Juaid, J. Fraser. Stoddart, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2015 Volume 54(Issue 4) pp:1785-1790
Publication Date(Web):January 29, 2015
DOI:10.1021/ic502697y
Intentional incorporation of defect sites functionalized with free carboxylic acid groups was achieved in a paddlewheel-based metal–organic framework (MOF) of rht topology, NU-125. Solvent-assisted linker exchange (SALE) performed on a mixed-linker derivative of NU-125 containing isophthalate (IPA) linkers (NU-125-IPA) led to the selective replacement of the IPA linkers in the framework with a conjugate base of trimesic acid (H3BTC). Only two of the three carboxylic acid moieties offered by H3BTC coordinate to the Cu2 centers in the MOF, yielding a rare example of a MOF decorated with free −COOH groups. The presence of the −COOH groups was confirmed by diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS); moreover, these groups were found to be available for postsynthesis elaboration (selective monoester formation). This work constitutes an example of the use of SALE to obtain otherwise challenging-to-synthesize MOFs. The resulting MOF, in turn, can serve as a platform for accomplishing selective organic transformations, in this case, exclusive monoesterification of trimesic acid.
Co-reporter:Mitchell H. Weston; William Morris; Paul W. Siu; William J. Hoover; David Cho; Rachelle K. Richardson
Inorganic Chemistry 2015 Volume 54(Issue 17) pp:8162-8164
Publication Date(Web):August 14, 2015
DOI:10.1021/acs.inorgchem.5b01055
For the first time, phosphine adsorption has been evaluated in a series of metal–organic frameworks (MOFs). Open-metal coordination sites were found to significantly enhance the ability of MOFs to adsorb highly toxic phosphine gas, with the identity of the open-metal site also modulating the amount of gas adsorbed. The MOFs studied outperform activated carbon, a commonly used material to capture phosphine.
Co-reporter:Gregory W. Peterson, Su-Young Moon, George W. Wagner, Morgan G. Hall, Jared B. DeCoste, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2015 Volume 54(Issue 20) pp:9684-9686
Publication Date(Web):October 2, 2015
DOI:10.1021/acs.inorgchem.5b01867
Evaluation of UiO-66 and UiO-67 metal–organic framework derivatives as catalysts for the degradation of soman, a chemical warfare agent, showed the importance of both the linker size and functionality. The best catalysts yielded half-lives of less than 1 min. Further testing with a nerve agent simulant established that different rate-assessment techniques yield similar values for degradation half-lives.
Co-reporter:Ashlee J. Howarth, Yangyang Liu, Joseph T. Hupp and Omar K. Farha
CrystEngComm 2015 vol. 17(Issue 38) pp:7245-7253
Publication Date(Web):12 Aug 2015
DOI:10.1039/C5CE01428J
Water pollution is an issue that should be carefully monitored and addressed. A major source of water pollution originates from high temperature industrial processes such as fossil fuel combustion and solid waste incineration. This waste typically contains high levels of oxyanion/cation forming elements which are particularly hazardous due to their inherent solubility in water and their resulting bioavailability. One approach for oxyanion/cation removal from water involves using an adsorbing medium to soak up and remove pollutants. Metal–organic frameworks (MOFs) offer an interesting platform for water remediation. MOFs are structurally diverse, porous materials that are constructed from metal nodes bridged by organic ligands. This highlight will focus on oxyanion/cation (PO43−, AsO43−, SeO32−, SeO42−, UO22+) removal from aqueous solutions using MOFs as contaminant-selective sponges. The mechanism of adsorption in different frameworks will be explored to gain insight into some design features that are important for MOFs to be used in applications to help alleviate water pollution.
Co-reporter:Jared B. DeCoste, Tyler J. Demasky, Michael J. Katz, Omar K. Farha and Joseph T. Hupp
New Journal of Chemistry 2015 vol. 39(Issue 4) pp:2396-2399
Publication Date(Web):07 Jan 2015
DOI:10.1039/C4NJ02093F
Zirconium-based metal–organic frameworks (MOFs) are of great importance as sorbents due to their increased chemical and thermal stability when compared to other MOF families. Here we report a novel analogue of UiO-66 modified with oxalic acid via solvent-assisted ligand incorporation. This analogue has the ability to remove ammonia, cyanogen chloride, sulphur dioxide, nitrogen dioxide and octane at levels greater than or equal to the base UiO-66. We report here the highest known capacities exhibited by a MOF for SO2 and NO2, at pressures less than 0.10 bar and at room temperature, by UiO-66-ox. Furthermore, we show here the importance of the secondary building unit of the MOF in the removal of ammonia and cyanogen chloride.
Co-reporter:Kainan Zhang, Ying Yu, SonBinh T. Nguyen, Joseph T. Hupp, Linda J. Broadbelt, and Omar K. Farha
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 3) pp:922-927
Publication Date(Web):December 29, 2014
DOI:10.1021/ie504550p
Fluorinated Fe-porphyrins, especially [tetrakis(pentafluorophenyl)porphyrinato]iron(III) chloride (tetrakis(pentafluorophenyl)porphyrinato = TPFPP) (TPFPP)FeCl (Fepor-2a), were found to be highly efficient for catalyzing the double epoxidation of divinylbenzene (DVB) to divinylbenzene dioxide (DVBDO), a novel component of epoxy resin formulation. The electronic properties of the catalysts are highly dependent on the substituents on the phenyl groups of these metalloporphyrins. The electron-rich fluorinated Fe-porphyrins are more selective toward epoxidation but are more vulnerable toward decomposition in H2O2. On the other hand, the electron deficient Fe-porphyrins are more stable, yet more Lewis acidic, which facilitates the formation of byproducts such as epoxide ring opening and overoxidation.
Co-reporter:Idan Hod; Wojciech Bury; Daniel M. Gardner; Pravas Deria; Vladimir Roznyatovskiy; Michael R. Wasielewski; Omar K. Farha;Joseph T. Hupp
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 4) pp:586-591
Publication Date(Web):January 26, 2015
DOI:10.1021/acs.jpclett.5b00019
The installation of ferrocene molecules within the wide-channel metal–organic framework (MOF) compound, NU-1000, and subsequent configuration of the modified MOF as thin-film coatings on electrodes renders the MOF electroactive in the vicinity of the ferrocenium/ferrocene (Fc+/Fc) redox potential due to redox hopping between anchored Fc+/0 species. The observation of effective site-to-site redox hopping points to the potential usefulness of the installed species as a redox shuttle in photoelectrochemical or electrocatalytic systems. At low supporting electrolyte concentration, we observe bias-tunable ionic permselectivity; films are blocking toward solution cations when the MOF is in the ferrocenium form but permeable when in the ferrocene form. Additionally, with ferrocene-functionalized films, we observe that the MOF’s pyrene-based linkers, which are otherwise reversibly electroactive, are now redox-silent. Linker electroactivity is fully recovered, however, when the electrolyte concentration is increased 10-fold, that is, to a concentration similar to or exceeding that of an anchored shuttle molecule. The findings have clear implications for the design and use of MOF-based sensors, electrocatalysts, and photoelectrochemical devices.
Co-reporter:Yangyang Liu, Su-Young Moon, Joseph T. Hupp, and Omar K. Farha
ACS Nano 2015 Volume 9(Issue 12) pp:12358
Publication Date(Web):October 20, 2015
DOI:10.1021/acsnano.5b05660
The nanocrystals of a porphyrin-based zirconium(IV) metal–organic framework (MOF) are used as a dual-function catalyst for the simultaneous detoxification of two chemical warfare agent simulants at room temperature. Simulants of nerve agent (such as GD, VX) and mustard gas, dimethyl 4-nitrophenyl phosphate and 2-chloroethyl ethyl sulfide, have been hydrolyzed and oxidized, respectively, to nontoxic products via a pair of pathways catalyzed by the same MOF. Phosphotriesterase-like activity of the Zr6-containing node combined with photoactivity of the porphyrin linker gives rise to a versatile MOF catalyst. In addition, bringing the MOF crystals down to the nanoregime leads to acceleration of the catalysis.Keywords: CEES; chemical warfare agents; DMNP; dual function; GD; heterogeneous catalysis; metal−organic frameworks; Simulant; Soman; VX;
Co-reporter:Aaron W. Peters, Zhanyong Li, Omar K. Farha, and Joseph T. Hupp
ACS Nano 2015 Volume 9(Issue 8) pp:8484
Publication Date(Web):August 4, 2015
DOI:10.1021/acsnano.5b03429
Atomic layer deposition (ALD) has been employed as a new synthetic route to thin films of cobalt sulfide on silicon and fluorine-doped tin oxide platforms. The self-limiting nature of the stepwise synthesis is established through growth rate studies at different pulse times and temperatures. Additionally, characterization of the materials by X-ray diffraction and X-ray photoelectron spectroscopy indicates that the crystalline phase of these films has the composition Co9S8. The nodes of the metal–organic framework (MOF) NU-1000 were then selectively functionalized with cobalt sulfide via ALD in MOFs (AIM). Spectroscopic techniques confirm uniform deposition of cobalt sulfide throughout the crystallites, with no loss in crystallinity or porosity. The resulting material, CoS-AIM, is catalytically active for selective hydrogenation of m-nitrophenol to m-aminophenol, and outperforms the analogous oxide AIM material (CoO-AIM) as well as an amorphous CoSx reference material. These results reveal AIM to be an effective method of incorporating high surface area and catalytically active cobalt sulfide in metal–organic frameworks.Keywords: atomic layer deposition; metal−organic framework; nanoscale Co9S8 films;
Co-reporter:Pravas Deria, Joseph E. Mondloch, Olga Karagiaridi, Wojciech Bury, Joseph T. Hupp and Omar K. Farha
Chemical Society Reviews 2014 vol. 43(Issue 16) pp:5896-5912
Publication Date(Web):11 Apr 2014
DOI:10.1039/C4CS00067F
Metal–organic frameworks (MOFs) are hybrid porous materials with many potential applications, which intimately depend on the presence of chemical functionality either at the organic linkers and/or at the metal nodes. Functionality that cannot be introduced into MOFs directly via de novo syntheses can be accessed through post-synthesis modification (PSM) on the reactive moieties of the linkers and/or nodes without disrupting the metal–linker bonds. Even more intriguing methods that go beyond PSM are herein termed building block replacement (BBR) which encompasses (i) solvent-assisted linker exchange (SALE), (ii) non-bridging ligand replacement, and (iii) transmetalation. These one-step or tandem BBR processes involve exchanging key structural components of the MOF, which in turn should allow for the evolution of protoMOF structures (i.e., the utilization of a parent MOF as a template) to design MOFs composed of completely new components, presumably via single crystal to single crystal transformations. The influence of building block replacement on the stability and properties of MOFs will be discussed, and some insights into their mechanistic aspects are provided. Future perspectives providing a glimpse into how these techniques can lead to various unexplored areas of MOF chemistry are also presented.
Co-reporter:Idan Hod;Wojciech Bury;David M. Karlin;Pravas Deria;Chung-Wei Kung;Michael J. Katz;Monica So;Benjamin Klahr;Danni Jin;Yip-Wah Chung;Teri W. Odom;Joseph T. Hupp
Advanced Materials 2014 Volume 26( Issue 36) pp:6295-6300
Publication Date(Web):
DOI:10.1002/adma.201401940
Co-reporter:M. Hassan Beyzavi ; Rachel C. Klet ; Samat Tussupbayev ; Joshua Borycz ; Nicolaas A. Vermeulen ; Christopher J. Cramer ; J. Fraser Stoddart ; Joseph T. Hupp
Journal of the American Chemical Society 2014 Volume 136(Issue 45) pp:15861-15864
Publication Date(Web):October 30, 2014
DOI:10.1021/ja508626n
Porous heterogeneous catalysts play a pivotal role in the chemical industry. Herein a new Hf-based metal–organic framework (Hf-NU-1000) incorporating Hf6 clusters is reported. It demonstrates high catalytic efficiency for the activation of epoxides, facilitating the quantitative chemical fixation of CO2 into five-membered cyclic carbonates under ambient conditions, rendering this material an excellent catalyst. As a multifunctional catalyst, Hf-NU-1000 is also efficient for other epoxide activations, leading to the regioselective and enantioretentive formation of 1,2-bifuctionalized systems via solvolytic nucleophilic ring opening.
Co-reporter:Jeremiah J. Gassensmith ; Jeung Yoon Kim ; James M. Holcroft ; Omar K. Farha ; J. Fraser Stoddart ; Joseph T. Hupp ;Nak Cheon Jeong
Journal of the American Chemical Society 2014 Volume 136(Issue 23) pp:8277-8282
Publication Date(Web):May 14, 2014
DOI:10.1021/ja5006465
The free primary hydroxyl groups in the metal–organic framework of CDMOF-2, an extended cubic structure containing units of six γ-cyclodextrin tori linked together in cube-like fashion by rubidium ions, has been shown to react with gaseous CO2 to form alkyl carbonate functions. The dynamic covalent carbon–oxygen bond, associated with this chemisorption process, releases CO2 at low activation energies. As a result of this dynamic covalent chemistry going on inside a metal–organic framework, CO2 can be detected selectively in the atmosphere by electrochemical impedance spectroscopy. The “as-synthesized” CDMOF-2 which exhibits high proton conductivity in pore-filling methanolic media, displays a ∼550-fold decrease in its ionic conductivity on binding CO2. This fundamental property has been exploited to create a sensor capable of measuring CO2 concentrations quantitatively even in the presence of ambient oxygen.
Co-reporter:Ryan K. Totten, Laura L. Olenick, Ye-Seong Kim, Sanjiban Chakraborty, Mitchell H. Weston, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science 2014 vol. 5(Issue 2) pp:782-787
Publication Date(Web):09 Oct 2013
DOI:10.1039/C3SC52010B
Porous organic polymers (POPs) with tunable pore volumes and surface areas can be made from a series of SnIV(porphyrins) functionalized with labile, bulky trans-diaxial ligands. Varying the ligand size allows for the tuning of the micropore volume while supercritical CO2 processing resulted in excellent enhancements of the total pore volumes.
Co-reporter:Diego A. Gomez-Gualdron, Oleksii V. Gutov, Vaiva Krungleviciute, Bhaskarjyoti Borah, Joseph E. Mondloch, Joseph T. Hupp, Taner Yildirim, Omar K. Farha, and Randall Q. Snurr
Chemistry of Materials 2014 Volume 26(Issue 19) pp:5632
Publication Date(Web):September 16, 2014
DOI:10.1021/cm502304e
A metal–organic framework (MOF) with high volumetric deliverable capacity for methane was synthesized after being identified by computational screening of 204 hypothetical MOF structures featuring (Zr6O4)(OH)4(CO2)n inorganic building blocks. The predicted MOF (NU-800) has an fcu topology in which zirconium nodes are connected via ditopic 1,4-benzenedipropynoic acid linkers. Based on our computer simulations, alkyne groups adjacent to the inorganic zirconium nodes provide more efficient methane packing around the nodes at high pressures. The high predicted gas uptake properties of this new MOF were confirmed by high-pressure isotherm measurements over a large temperature and pressure range. The measured methane deliverable capacity of NU-800 between 65 and 5.8 bar is 167 cc(STP)/cc (0.215 g/g), the highest among zirconium-based MOFs. High-pressure uptake values of H2 and CO2 are also among the highest reported. These high gas uptake characteristics, along with the expected highly stable structure of NU-800, make it a promising material for gas storage applications.
Co-reporter:Huong Giang T. Nguyen, Neil M. Schweitzer, Chih-Yi Chang, Tasha L. Drake, Monica C. So, Peter C. Stair, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
ACS Catalysis 2014 Volume 4(Issue 8) pp:2496
Publication Date(Web):June 2, 2014
DOI:10.1021/cs5001448
The OH groups on the Zr-based nodes of ultrastable UiO-66 can be metallated with VV ions in a facile fashion to give the derivative VUiO-66. This metallated MOF exhibits high stability over a broad temperature range and displays high selectivity for benzene under low-conversion conditions in the vapor-phase oxidative dehydrogenation of cyclohexene (activation energy ∼110 kJ/mol). The integrity of the MOF is maintained after catalysis as determined by PXRD, ICP-AES, and SEM.Keywords: cyclohexene oxidation; gas-phase catalysis; metal−organic framework; UiO-66; vanadium
Co-reporter:Gokhan Barin, Vaiva Krungleviciute, Diego A. Gomez-Gualdron, Amy A. Sarjeant, Randall Q. Snurr, Joseph T. Hupp, Taner Yildirim, and Omar K. Farha
Chemistry of Materials 2014 Volume 26(Issue 5) pp:1912
Publication Date(Web):February 6, 2014
DOI:10.1021/cm404155s
We have successfully used a highly efficient copper-catalyzed “click” reaction for the synthesis of a new series of hexacarboxylic acid linkers with varying sizes for the construction of isoreticular (3,24)-connected metal–organic frameworks (MOFs)—namely, NU-138, NU-139, and NU-140. One of these MOFs, NU-140, exhibits a gravimetric methane uptake of 0.34 g/g at 65 bar and 298 K, corresponding to almost 70% of the DOE target (0.5 g/g), and has a working capacity (deliverable amount between 65 and 5 bar) of 0.29 g/g, which translates into a volumetric working capacity of 170 cc(STP)/cc. These values demonstrate that NU-140 performs well for methane storage purposes, from both a gravimetric and a volumetric point of view. Adsorption of CO2 and H2 along with simulated isotherms are also reported.
Co-reporter:Mitchell H. Weston, Yamil J. Colón, Youn-Sang Bae, Sergio J. Garibay, Randall Q. Snurr, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2014 vol. 2(Issue 2) pp:299-302
Publication Date(Web):04 Oct 2013
DOI:10.1039/C3TA12999C
A porous organic polymer decorated with high densities of copper(catecholate) groups was prepared and characterized. Single-component propylene and propane isotherms measured at ambient temperatures and ideal adsorption solution theory (IAST) calculations revealed increasing propylene/propane selectivities with increasing pressures.
Co-reporter:Vennesa O. Williams, Erica J. DeMarco, Michael J. Katz, Joseph A. Libera, Shannon C. Riha, Dong Wook Kim, Jason R. Avila, Alex B. F. Martinson, Jeffrey W. Elam, Michael J. Pellin, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:12290
Publication Date(Web):July 17, 2014
DOI:10.1021/am501910n
Highly ordered, and conductive inverse opal arrays were made with silica and subsequently coated with tin-doped indium oxide (ITO) via atomic layer deposition (ALD). We demonstrate the utility of the resulting mesostructured electrodes by further coating them with nickel oxide via ALD. The NiO-coated arrays are capable of efficiently electrochemically evolving oxygen from water. These modular, crack-free, transparent, high surface area, and conducting structures show promise for many applications including electrocatalysis, photocatalysis, and dye-sensitized solar cells.Keywords: atomic-layer deposition; catalysis; electrochemistry; inverse opals; nickel oxide; water oxidation
Co-reporter:William L. Hoffeditz, Michael J. Katz, Pravas Deria, Alex B.F. Martinson, Michael J. Pellin, Omar K. Farha, and Joseph T. Hupp
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 11) pp:8646
Publication Date(Web):May 14, 2014
DOI:10.1021/am501455b
Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited significantly higher charge transfer resistances at the dark electrode. This often results in poor fill factor, a severe detriment to device performance. Rather than moving to dark electrodes of untested materials that may have higher catalytic activity for specific shuttles, the surface area of platinum dark electrodes could be increased, improving the catalytic activity by simply presenting more catalyst to the shuttle solution. A new copper-based redox shuttle that experiences extremely high charge-transfer resistance at conventional Pt dark electrodes yields cells having fill-factors of less than 0.3. By replacing the standard Pt dark electrode with an inverse opal Pt electrode fabricated via atomic layer deposition, the dark electrode surface area is boosted by ca. 50-fold. The resulting increase in interfacial electron transfer rate (decrease in charge-transfer resistance) nearly doubles the fill factor and therefore the overall energy conversion efficiency, illustrating the utility of this high-area electrode for DSCsKeywords: dark electrode; dye cell; fill factor; inverse opal;
Co-reporter:Pravas Deria, Wojciech Bury, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2014 vol. 50(Issue 16) pp:1965-1968
Publication Date(Web):09 Jan 2014
DOI:10.1039/C3CC48562E
Solvent-assisted ligand incorporation (SALI) was utilized to efficiently insert various carboxylate-derived functionalities into the Zr-based metal–organic framework NU-1000 as charge compensating moieties strongly bound to the Zr6 nodes. SALI-derived functionalities are accessible for further chemical reactions such as click chemistry, imine condensation and pyridine quaternization.
Co-reporter:Joseph E. Mondloch, Michael J. Katz, Nora Planas, David Semrouni, Laura Gagliardi, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2014 vol. 50(Issue 64) pp:8944-8946
Publication Date(Web):30 Jun 2014
DOI:10.1039/C4CC02401J
Metal–organic frameworks (MOFs) built up from Zr6-based nodes and multi-topic carboxylate linkers have attracted attention due to their favourable thermal and chemical stability. However, the hydrolytic stability of some of these Zr6-based MOFs has recently been questioned. Herein we demonstrate that two Zr6-based frameworks, namely UiO-67 and NU-1000, are stable towards linker hydrolysis in H2O, but collapse during activation from H2O. Importantly, this framework collapse can be overcome by utilizing solvent-exchange to solvents exhibiting lower capillary forces such as acetone.
Co-reporter:Olga Karagiaridi, Wojciech Bury, David Fairen-Jimenez, Christopher E. Wilmer, Amy A. Sarjeant, Joseph T. Hupp, and Omar K. Farha
Inorganic Chemistry 2014 Volume 53(Issue 19) pp:10432-10436
Publication Date(Web):September 8, 2014
DOI:10.1021/ic501467w
The synthesis of a permanently porous pillared-paddlewheel metal–organic framework (MOF) was achieved through transmetalation of Zn(II) with Ni(II). The MOF can be treated with liquid water, leading to the reversible displacement of 50% of its pillars by water molecules and resulting in a most unusual crystalline and permanently porous structure.
Co-reporter:Gokhan Barin, Vaiva Krungleviciute, Oleksii Gutov, Joseph T. Hupp, Taner Yildirim, and Omar K. Farha
Inorganic Chemistry 2014 Volume 53(Issue 13) pp:6914-6919
Publication Date(Web):June 6, 2014
DOI:10.1021/ic500722n
We successfully demonstrate an approach based on linker fragmentation to create defects and tune the pore volumes and surface areas of two metal–organic frameworks, NU-125 and HKUST-1, both of which feature copper paddlewheel nodes. Depending on the linker fragment composition, the defect can be either a vacant site or a functional group that the original linker does not have. In the first case, we show that both surface area and pore volume increase, while in the second case they decrease. The effect of defects on the high-pressure gas uptake is also studied over a large temperature and pressure range for different gases. We found that despite an increase in pore volume and surface area in structures with vacant sites, the absolute adsorption for methane decreases for HKUST-1 and slightly increases for NU-125. However, the working capacity (deliverable amount between 65 and 5 bar) in both cases remains similar to parent frameworks due to lower uptakes at low pressures. In the case of NU-125, the effect of defects became more pronounced at lower temperatures, reflecting the greater surface areas and pore volumes of the altered forms.
Co-reporter:Sherzod T. Madrahimov, Tulay A. Atesin, Olga Karagiaridi, Amy A. Sarjeant, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
Crystal Growth & Design 2014 Volume 14(Issue 12) pp:6320-6324
Publication Date(Web):September 29, 2014
DOI:10.1021/cg501066s
A series of metal–organic framework (MOF) materials containing AuI-carbon covalent bonds was prepared by solvent-assisted linker exchange (SALE) between (alkynyl)gold(phosphine)-functionalized bipyridine linkers and the bipyridyl naphthalene tetracarboxydiimide struts in Zn pillared-paddlewheel MOFs. These new materials could not be obtained by the authors through de novo synthesis or post-synthesis modification, both of which lead to the decomposition of the organometallic complex. In contrast, the SALE process occurs readily under mild conditions that preserve the integrity of both the pillared-paddlewheel structure and the organometallic complex. For bipyridine linkers with similar basicities, the rate of the SALE exhibits a strong inverse dependence on the size of the phosphine ligand in the incoming (alkynyl)gold(phosphine)-functionalized linker, with smaller ligands reacting faster.
Co-reporter:Olga Karagiaridi;Dr. Wojciech Bury;Dr. Joseph E. Mondloch;Dr. Joseph T. Hupp;Dr. Omar K. Farha
Angewandte Chemie International Edition 2014 Volume 53( Issue 18) pp:4530-4540
Publication Date(Web):
DOI:10.1002/anie.201306923
Abstract
Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials—in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function–property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool.
Co-reporter:Dr. Michael J. Katz;Dr. Joseph E. Mondloch;Dr. Ryan K. Totten;Dr. Jin K. Park; SonBinh T. Nguyen; Omar K. Farha; Joseph T. Hupp
Angewandte Chemie International Edition 2014 Volume 53( Issue 2) pp:497-501
Publication Date(Web):
DOI:10.1002/anie.201307520
Abstract
Inspired by biology, in which a bimetallic hydroxide-bridged zinc(II)-containing enzyme is utilized to catalytically hydrolyze phosphate ester bonds, the utility of a zirconium(IV)-cluster-containing metal–organic framework as a catalyst for the methanolysis and hydrolysis of phosphate-based nerve agent simulants was examined. The combination of the strong Lewis-acidic ZrIV and bridging hydroxide anions led to ultrafast half-lives for these solvolysis reactions. This is especially remarkable considering that the actual catalyst loading was a mere 0.045 % as a result of the surface-only catalysis observed.
Co-reporter:Dr. Oleksii V. Gutov;Dr. Wojciech Bury;Dr. Diego A. Gomez-Gualdron;Dr. Vaiva Krungleviciute;Dr. David Fairen-Jimenez;Dr. Joseph E. Mondloch;Dr. Amy A. Sarjeant;Salih S. Al-Juaid;Dr. Rall Q. Snurr;Dr. Joseph T. Hupp;Dr. Taner Yildirim;Dr. Omar K. Farha
Chemistry - A European Journal 2014 Volume 20( Issue 39) pp:12389-12393
Publication Date(Web):
DOI:10.1002/chem.201402895
Abstract
We designed, synthesized, and characterized a new Zr-based metal–organic framework material, NU-1100, with a pore volume of 1.53 ccg−1 and Brunauer–Emmett–Teller (BET) surface area of 4020 m2g−1; to our knowledge, currently the highest published for Zr-based MOFs. CH4/CO2/H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g−1, which corresponds to 43 g L−1. The volumetric and gravimetric methane-storage capacities at 65 bar and 298 K are approximately 180 vSTP/v and 0.27 g g−1, respectively.
Co-reporter:Nora Planas, Joseph E. Mondloch, Samat Tussupbayev, Joshua Borycz, Laura Gagliardi, Joseph T. Hupp, Omar K. Farha, and Christopher J. Cramer
The Journal of Physical Chemistry Letters 2014 Volume 5(Issue 21) pp:3716-3723
Publication Date(Web):October 10, 2014
DOI:10.1021/jz501899j
Metal–organic frameworks (MOFs) constructed from Zr6-based nodes have recently received considerable attention given their exceptional thermal, chemical, and mechanical stability. Because of this, the structural diversity of Zr6-based MOFs has expanded considerably and in turn given rise to difficulty in their precise characterization. In particular it has been difficult to assign where protons (needed for charge balance) reside on some Zr6-based nodes. Elucidating the precise proton topologies in Zr6-based MOFs will have wide ranging implications in defining their chemical reactivity, acid/base characteristics, conductivity, and chemical catalysis. Here we have used a combined quantum mechanical and experimental approach to elucidate the precise proton topology of the Zr6-based framework NU-1000. Our data indicate that a mixed node topology, [Zr6(μ3–O)4(μ3–OH)4(OH)4 (OH2)4]8+, is preferred and simultaneously rule out five alternative node topologies.Keywords: density functional theory; IR spectroscopy; node topology; tautomerism;
Co-reporter:Dr. Jared B. DeCoste;Dr. Mitchell H. Weston;Patrick E. Fuller;Trenton M. Tovar;Gregory W. Peterson;Dr. M. Douglas LeVan;Dr. Omar K. Farha
Angewandte Chemie International Edition 2014 Volume 53( Issue 51) pp:14092-14095
Publication Date(Web):
DOI:10.1002/anie.201408464
Abstract
We present a systematic study of metal–organic frameworks (MOFs) for the storage of oxygen. The study starts with grand canonical Monte Carlo simulations on a suite of 10 000 MOFs for the adsorption of oxygen. From these data, the MOFs were down selected to the prime candidates of HKUST-1 (Cu-BTC) and NU-125, both with coordinatively unsaturated Cu sites. Oxygen isotherms up to 30 bar were measured at multiple temperatures to determine the isosteric heat of adsorption for oxygen on each MOF by fitting to a Toth isotherm model. High pressure (up to 140 bar) oxygen isotherms were measured for HKUST-1 and NU-125 to determine the working capacity of each MOF. Compared to the zeolite NaX and Norit activated carbon, NU-125 has an increased excess capacity for oxygen of 237 % and 98 %, respectively. These materials could ultimately prove useful for oxygen storage in medical, military, and aerospace applications.
Co-reporter:Christopher E. Wilmer, Omar K. Farha, Taner Yildirim, Ibrahim Eryazici, Vaiva Krungleviciute, Amy A. Sarjeant, Randall Q. Snurr and Joseph T. Hupp
Energy & Environmental Science 2013 vol. 6(Issue 4) pp:1158-1163
Publication Date(Web):07 Mar 2013
DOI:10.1039/C3EE24506C
We have synthesized and characterized a new metal–organic framework (MOF) material, NU-125, that, in the single-crystal limit, achieves a methane storage density at 58 bar (840 psi) and 298 K corresponding to 86% of that obtained with compressed natural gas tanks (CNG) used in vehicles today, when the latter are pressurized to 248 bar (3600 psi). More importantly, the deliverable capacity (58 bar to 5.8 bar) for NU-125 is 67% of the deliverable capacity of a CNG tank that starts at 248 bar. (For crystalline granules or powders, particle packing inefficiencies will yield densities and deliverable capacities lower than 86% and 67% of high-pressure CNG.) This material was synthesized in high yield on a gram-scale in a single-batch synthesis. Methane adsorption isotherms were measured over a wide pressure range (0.1–58 bar) and repeated over twelve cycles on the same sample, which showed no detectable degradation. Adsorption of CO2 and H2 over a broad range of pressures and temperatures are also reported and agree with our computational findings.
Co-reporter:Pravas Deria, Joseph E. Mondloch, Emmanuel Tylianakis, Pritha Ghosh, Wojciech Bury, Randall Q. Snurr, Joseph T. Hupp, and Omar K. Farha
Journal of the American Chemical Society 2013 Volume 135(Issue 45) pp:16801-16804
Publication Date(Web):October 31, 2013
DOI:10.1021/ja408959g
A new functionalization technique, solvent-assisted ligand incorporation (SALI), was developed to efficiently incorporate carboxylate-based functionalities in the Zr-based metal–organic framework, NU-1000. Unlike previous metal node functionalization strategies, which utilize dative bonding to coordinatively unsaturated metal sites, SALI introduces functional groups as charge compensating and strongly bound moieties to the Zr6 node. Utilizing SALI, we have efficiently attached perfluoroalkane carboxylates of various chain lengths (C1–C9) on the Zr6 nodes of NU-1000. These fluoroalkane-functionalized mesoporous MOFs, termed herein SALI-n, were studied experimentally and theoretically as potential CO2 capture materials.
Co-reporter:Chaiya Prasittichai ; Jason R. Avila ; Omar K. Farha ;Joseph T. Hupp
Journal of the American Chemical Society 2013 Volume 135(Issue 44) pp:16328-16331
Publication Date(Web):October 22, 2013
DOI:10.1021/ja4089555
Ultrathin films of TiO2, ZrO2, and Al2O3 were conformally created on SnO2 and TiO2 photoelectrodes via atomic layer deposition (ALD) to examine their influence upon electron transfer (ET) from the electrodes to a representative molecular receptor, I3–. Films thicker than 2 Å engender an exponential decrease in ET time with increasing film thickness, consistent with tunneling theory. Increasing the height of the barrier, as measured by the energy difference between the transferring electron and the bottom of the conduction band of the barrier material, results in steeper exponential drops in tunneling rate or probability. The variations are quantitatively consistent with a simple model of quantum tunneling of electrons through square barriers (i.e., barriers of individually uniform energy height) that are characterized by individually uniform physical thickness. The findings demonstrate that ALD is a remarkably uniform and precise method for modifying electrode surfaces and imply that standard tunneling theory can be used as a quantitative guide to intentionally and predictively modulating rates of ET between molecules and electrodes.
Co-reporter:Monica C. So ; Shengye Jin ; Ho-Jin Son ; Gary P. Wiederrecht ; Omar K. Farha ;Joseph T. Hupp
Journal of the American Chemical Society 2013 Volume 135(Issue 42) pp:15698-15701
Publication Date(Web):October 15, 2013
DOI:10.1021/ja4078705
We report the synthesis and characterization of two thin films (DA-MOF and L2-MOF) of porphyrin-based MOFs on functionalized surfaces using a layer-by-layer (LbL) approach. Profilometry measurements confirm that the film thickness increases systematically with number of growth cycles. Polarization excitation and fluorescence measurements indicate that the porphyrin units are preferentially oriented, while X-ray reflectivity scans point to periodic ordering. Ellipsometry measurements show that the films are highly porous. Since there are currently few methods capable of yielding microporous MOFs containing accessible free-base porphyrins, it is noteworthy that the LbL growth permits direct MOF incorporation of unmetalated porphyrins. Long-range energy transfer is demonstrated for both MOF films. The findings offer useful insights for subsequent fabrication of MOF-based solar energy conversion devices.
Co-reporter:Joseph E. Mondloch ; Wojciech Bury ; David Fairen-Jimenez ; Stephanie Kwon ; Erica J. DeMarco ; Mitchell H. Weston ; Amy A. Sarjeant ; SonBinh T. Nguyen ; Peter C. Stair ; Randall Q. Snurr ; Omar K. Farha ;Joseph T. Hupp
Journal of the American Chemical Society 2013 Volume 135(Issue 28) pp:10294-10297
Publication Date(Web):July 5, 2013
DOI:10.1021/ja4050828
Metal–organic frameworks (MOFs) have received attention for a myriad of potential applications including catalysis, gas storage, and gas separation. Coordinatively unsaturated metal ions often enable key functional behavior of these materials. Most commonly, MOFs have been metalated from the condensed phase (i.e., from solution). Here we introduce a new synthetic strategy capable of metallating MOFs from the gas phase: atomic layer deposition (ALD). Key to enabling metalation by ALD In MOFs (AIM) was the synthesis of NU-1000, a new, thermally stable, Zr-based MOF with spatially oriented −OH groups and large 1D mesopores and apertures.
Co-reporter:Ryan K. Totten ; Ye-Seong Kim ; Mitchell H. Weston ; Omar K. Farha ; Joseph T. Hupp ;SonBinh T. Nguyen
Journal of the American Chemical Society 2013 Volume 135(Issue 32) pp:11720-11723
Publication Date(Web):July 22, 2013
DOI:10.1021/ja405495u
An Al(porphyrin) functionalized with a large axial ligand was incorporated into a porous organic polymer (POP) using a cobalt-catalyzed acetylene trimerization strategy. Removal of the axial ligand afforded a microporous POP that is catalytically active in the methanolysis of a nerve agent simulant. Supercritical CO2 processing of the POP dramatically increased the pore size and volume, allowing for significantly higher catalytic activities.
Co-reporter:Ho-Jin Son ; Chaiya Prasittichai ; Joseph E. Mondloch ; Langli Luo ; Jinsong Wu ; Dong Wook Kim ; Omar K. Farha ;Joseph T. Hupp
Journal of the American Chemical Society 2013 Volume 135(Issue 31) pp:11529-11532
Publication Date(Web):July 22, 2013
DOI:10.1021/ja406538a
Detachment (desorption) of molecular dyes from photoelectrodes is one of the major limitations for the long-term operation of dye-sensitized solar cells. Here we demonstrate a method to greatly inhibit this loss by growing a transparent metal oxide (TiO2) on the dye-coated photoelectrode via atomic layer deposition (ALD). TiO2-enshrouded sensitizers largely resist detachment, even in pH 10.7 ethanol, a standard solution for intentional removal of molecular dyes from photoelectrodes. Additionally, the ALD post-treatment renders the otherwise hydrophobic dye-coated surface hydrophilic, thereby enhancing photoelectrode pore-filling with aqueous solution.
Co-reporter:Yang Peng ; Vaiva Krungleviciute ; Ibrahim Eryazici ; Joseph T. Hupp ; Omar K. Farha ;Taner Yildirim
Journal of the American Chemical Society 2013 Volume 135(Issue 32) pp:11887-11894
Publication Date(Web):July 10, 2013
DOI:10.1021/ja4045289
We have examined the methane uptake properties of six of the most promising metal organic framework (MOF) materials: PCN-14, UTSA-20, HKUST-1, Ni-MOF-74 (Ni-CPO-27), NU-111, and NU-125. We discovered that HKUST-1, a material that is commercially available in gram scale, exhibits a room-temperature volumetric methane uptake that exceeds any value reported to date. The total uptake is about 230 cc(STP)/cc at 35 bar and 270 cc(STP)/cc at 65 bar, which meets the new volumetric target recently set by the Department of Energy (DOE) if the packing efficiency loss is ignored. We emphasize that MOFs with high surface areas and pore volumes perform better overall. NU-111, for example, reaches ∼75% of both the gravimetric and the volumetric targets. We find that values for gravimetric uptake, pore volume, and inverse density of the MOFs we studied scale essentially linearly with surface area. From this linear dependence, we estimate that a MOF with surface area 7500 m2/g and pore volume 3.2 cc/g could reach the current DOE gravimetric target of 0.5 g/g while simultaneously exhibiting around ∼200 cc/cc volumetric uptake. We note that while values for volumetric uptake are based on ideal single crystal densities, in reality the packing densities of MOFs are much lower. Finally, we show that compacting HKUST-1 into wafer shapes partially collapses the framework, decreasing both volumetric and gravimetric uptake significantly. Hence, one of the important challenges going forward is to find ways to pack MOFs efficiently without serious damage or to synthesize MOFs that can withstand substantial mechanical pressure.
Co-reporter:Chung-Wei Kung, Timothy Chiaan Wang, Joseph E. Mondloch, David Fairen-Jimenez, Daniel M. Gardner, Wojciech Bury, Jordan Matthew Klingsporn, Jonathan C. Barnes, Richard Van Duyne, J. Fraser Stoddart, Michael R. Wasielewski, Omar K. Farha, and Joseph T. Hupp
Chemistry of Materials 2013 Volume 25(Issue 24) pp:5012
Publication Date(Web):December 13, 2013
DOI:10.1021/cm403726v
A uniform and crack-free metal–organic framework (MOF) thin film composed of free-standing acicular nanorods was grown on a transparent conducting glass substrate. The MOF thin film exhibits electrochromic switching between yellow and deep blue by means of a one-electron redox reaction at its pyrene-based linkers. The rigid MOF stabilizes the radical cations of the pyrene linkers at positive applied potential, resulting in the reversible color change of the MOF film. The regular and uniform channels of the MOF allow ions to migrate through the entire film. The MOF thin film thus exhibits a remarkable color change and rapid switching rate.Keywords: electrochromism; metal−organic frameworks; one-dimensional nanorods; pyrene;
Co-reporter:Olga Karagiaridi, Wojciech Bury, Emmanuel Tylianakis, Amy A. Sarjeant, Joseph T. Hupp, and Omar K. Farha
Chemistry of Materials 2013 Volume 25(Issue 17) pp:3499
Publication Date(Web):August 22, 2013
DOI:10.1021/cm401724v
Solvent-assisted linker exchange (SALE) was performed on a pillared-paddlewheel metal–organic framework (MOF), SALEM-5, to achieve incorporation of longer linkers into the material. The 9-Å meso-1,2-di(4-pyridyl)-1,2-ethanediol pillar of SALEM-5 was successfully replaced by 11-Å, 14-Å, and 17-Å pillars to generate daughter MOFs SALEM-6, SALEM-7, and SALEM-8. The daughter frameworks possess more open cages, as was demonstrated by structural modeling from the powder X-ray diffraction patterns, and larger solvent accessible space, as was demonstrated by thermogravimetric analysis. Finally, a study was performed to examine the effect of pKa of monoprotonated dipyridyl pillars (as an indicator of the Zn–L bond strength) on the outcome of SALE.Keywords: metal−organic frameworks; pKa; solvent-assisted linker exchange;
Co-reporter:Wojciech Bury, David Fairen-Jimenez, Marianne B. Lalonde, Randall Q. Snurr, Omar K. Farha, and Joseph T. Hupp
Chemistry of Materials 2013 Volume 25(Issue 5) pp:739
Publication Date(Web):February 9, 2013
DOI:10.1021/cm303749m
Control over catenation in a pillared paddlewheel metal–organic framework was achieved via solvent-assisted linker exchange. The linker exchange was demonstrated on the noncatenated structure of DO-MOF, by using 4,4′-bipyridine (L4) and 4,4′-azobis(pyridine) (L5) as linkers, leading to noncatenated materials SALEM-3 and SALEM-4. The de novo synthesized analogues of SALEM-3 and SALEM-4 can only be obtained as 2-fold interpenetrated frameworks. The reaction progress of the linker exchange was monitored by NMR spectroscopy, and structure and framework catenation were characterized by powder X-ray diffraction and thermogravimetric methods.Keywords: catenation; linker exchange; metal−organic frameworks; SALE;
Co-reporter:Brad G. Hauser, Omar K. Farha, Jason Exley, and Joseph T. Hupp
Chemistry of Materials 2013 Volume 25(Issue 1) pp:12
Publication Date(Web):December 4, 2012
DOI:10.1021/cm3022566
Thermal treatment of highly stable porous organic polymers based upon the Yamamoto polymerization of 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene was done. The polymers are shown to be thermally and chemically stable. Upon thermal treatment the polymers are shown to have BET surface areas of ca. 2,000 m2/g and 2,500 m2/g respectively.Keywords: gas storage; polymer processing; porous polymers;
Co-reporter:Ryan K. Totten, Mitchell H. Weston, Jin Kuen Park, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
ACS Catalysis 2013 Volume 3(Issue 7) pp:1454
Publication Date(Web):April 15, 2013
DOI:10.1021/cs4001738
Two robust catechol-functionalized porous organic polymers (catPOPs) with different Td-directing nodes were synthesized using a cobalt-catalyzed acetylene trimerization (CCAT) strategy. Postsynthesis metallation was readily carried out with La(acac)3 to afford catalytically active La-functionalized catPOPs for the solvolytic and hydrolytic degradation of the toxic organophosphate compound methyl paraoxon, a simulant for nerve agents.Keywords: catalysis; catechol; lanthanum; organophosphates; porous organic polymers
Co-reporter:Shinya Takaishi, Erica J. DeMarco, Michael J. Pellin, Omar K. Farha and Joseph T. Hupp
Chemical Science 2013 vol. 4(Issue 4) pp:1509-1513
Publication Date(Web):07 Dec 2012
DOI:10.1039/C2SC21516K
Using recently reported robust porphyrinic metal–organic framework (RPM) materials, we have examined the systematic exchange of pillaring linkers/struts as a means of accessing new versions of these materials. Dipyridyl-porphyrin Zn(II) (Zn-dipy) struts were successfully replaced by M2-dipy (M2 = 2H(+), Al(III), Sn(IV)), forming crystalline solid solutions of Zn(Zn1−xMx)-RPM in variable ratios. In addition, post-synthetic metallation was demonstrated using Zn2H-RPM, again with retention of crystallinity. We examined catalytic activity for an epoxide ring-opening reaction with a series of ZnM2-RPMs. The catalytic activity depends strongly on the identity of the metal ion present in the dipyridyl-porphyrin unit.
Co-reporter:Robert D. Kennedy, Vaiva Krungleviciute, Daniel J. Clingerman, Joseph E. Mondloch, Yang Peng, Christopher E. Wilmer, Amy A. Sarjeant, Randall Q. Snurr, Joseph T. Hupp, Taner Yildirim, Omar K. Farha, and Chad A. Mirkin
Chemistry of Materials 2013 Volume 25(Issue 17) pp:3539
Publication Date(Web):August 3, 2013
DOI:10.1021/cm4020942
A Cu–carborane-based metal–organic framework (MOF), NU-135, which contains a quasi-spherical para-carborane moiety, has been synthesized and characterized. NU-135 exhibits a pore volume of 1.02 cm3/g and a gravimetric BET surface area of ca. 2600 m2/g, and thus represents the first highly porous carborane-based MOF. As a consequence of the unique geometry of the carborane unit, NU-135 has a very high volumetric BET surface area of ca. 1900 m2/cm3. CH4, CO2, and H2 adsorption isotherms were measured over a broad range of pressures and temperatures and are in good agreement with computational predictions. The methane storage capacity of NU-135 at 35 bar and 298 K is ca. 187 vSTP/v. At 298 K, the pressure required to achieve a methane storage density comparable to that of a compressed natural gas (CNG) tank pressurized to 212 bar, which is a typical storage pressure, is only 65 bar. The methane working capacity (5–65 bar) is 170 vSTP/v. The volumetric hydrogen storage capacity at 55 bar and 77 K is 49 g/L. These properties are comparable to those of current record holders in the area of methane and hydrogen storage. This initial example lays the groundwork for carborane-based materials with high surface areas.Keywords: boron; carborane; coordination polymer; hydrogen; metal−organic framework; methane; MOF; porous;
Co-reporter:Marianne Lalonde, Wojciech Bury, Olga Karagiaridi, Zachary Brown, Joseph T. Hupp and Omar K. Farha
Journal of Materials Chemistry A 2013 vol. 1(Issue 18) pp:5453-5468
Publication Date(Web):21 Mar 2013
DOI:10.1039/C3TA10784A
The present work is a critical review of metal exchange (transmetalation) involving metal nodes and metalated struts in metal–organic frameworks. Particular emphasis is given to drawing parallels between different examples of transmetalation in order to understand the influence of coordination environment, solvents, nature of the metals and other variables on the process. We hope that the present review will be of use to those involved in the incorporation of various metal centers to create isostructural MOFs and study their properties.
Co-reporter:Yang Peng, Gadipelli Srinivas, Christopher E. Wilmer, Ibrahim Eryazici, Randall Q. Snurr, Joseph T. Hupp, Taner Yildirim and Omar K. Farha
Chemical Communications 2013 vol. 49(Issue 29) pp:2992-2994
Publication Date(Web):21 Feb 2013
DOI:10.1039/C3CC40819A
We show that the MOF NU-111 exhibits equally high volumetric and gravimetric methane uptake values, both within ≈75% of the DOE targets at 300 K. Upon reducing the temperature to 270 K, the uptake increases to 0.5 g g−1 and 284 cc(STP) per cc at 65 bar. Adsorption of CO2 and H2 is also reported. Simulated isotherms are in excellent agreement with those obtained from experiments.
Co-reporter:Mitchell H. Weston, Gregory W. Peterson, Matthew A. Browe, Paulette Jones, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2013 vol. 49(Issue 29) pp:2995-2997
Publication Date(Web):12 Feb 2013
DOI:10.1039/C3CC40475G
Porous organic polymers bearing metal–catecholate groups were evaluated for their ability to remove airborne ammonia, cyanogen chloride, sulphur dioxide, and octane by micro-breakthrough analysis. For ammonia, the metal–catecholate materials showed remarkable uptake under humid conditions.
Co-reporter:Michael J. Katz, Zachary J. Brown, Yamil J. Colón, Paul W. Siu, Karl A. Scheidt, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2013 vol. 49(Issue 82) pp:9449-9451
Publication Date(Web):06 Sep 2013
DOI:10.1039/C3CC46105J
A scalable, reproducible method of synthesizing UiO-66- and UiO-67-type MOFs, entailing the addition of HCl to the reaction mixture, has been investigated. The new protocol requires a fraction of the time of previously reported procedures, yields exceptional porosities, and works with a range of linkers.
Co-reporter:Paul W. Siu, Zachary J. Brown, Omar K. Farha, Joseph T. Hupp and Karl A. Scheidt
Chemical Communications 2013 vol. 49(Issue 93) pp:10920-10922
Publication Date(Web):10 Oct 2013
DOI:10.1039/C3CC47177B
A hydrogen-bond donating MOF catalyst based on the UiO-67 framework, containing both urea-functionalized dicarboxylate and biphenyl-4,4′-dicarboxylate struts, was synthesized by a de novo route. The mixed strut framework has larger pore sizes and improved catalytic activity for Henry reactions than the pure strut analogue, which contains only the urea-functionalized dicarboxylate linker.
Co-reporter:Sergio J. Garibay, Mitchell H. Weston, Joseph E. Mondloch, Yamil J. Colón, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
CrystEngComm 2013 vol. 15(Issue 8) pp:1515-1519
Publication Date(Web):22 Oct 2012
DOI:10.1039/C2CE26595H
Methyl-, hydroxymethyl-, and phthalimidomethyl-functionalized versions of the porous organic polymer PAF-1 have been obtained through de novo synthesis. The CO2 adsorption capacity of PAF-1–CH2NH2, obtained through the post-synthesis deprotection of PAF-1–CH2–phthalimide, has been shown to exceed that of PAF-1.
Co-reporter:Joseph E. Mondloch, Olga Karagiaridi, Omar K. Farha and Joseph T. Hupp
CrystEngComm 2013 vol. 15(Issue 45) pp:9258-9264
Publication Date(Web):11 Oct 2013
DOI:10.1039/C3CE41232F
Crystalline metal–organic frameworks (MOFs) have emerged as a highly desirable class of solid-state materials. Some of their most attractive features include exceptionally high porosities as well as surface areas. A key aspect to the realization of high porosity is the removal of guest molecules from the framework while still maintaining its structural integrity (i.e., “activation”). This contribution highlights the strategies utilized to date for activating MOFs, including: (i) conventional heating and vacuum; (ii) solvent-exchange; (iii) supercritical CO2 (scCO2) exchange; (iv) freeze-drying; and (v) chemical treatment.
Co-reporter:Marianne B. Lalonde, Rachel B. Getman, Jeong Yong Lee, John M. Roberts, Amy A. Sarjeant, Karl A. Scheidt, Peter A. Georgiev, Jan P. Embs, Juergen Eckert, Omar K. Farha, Randall Q. Snurr and Joseph T. Hupp
CrystEngComm 2013 vol. 15(Issue 45) pp:9408-9414
Publication Date(Web):06 Mar 2013
DOI:10.1039/C3CE40198G
Metal–organic frameworks (MOFs) are permanently porous, crystalline materials and promising hydrogen sorbents. However, the H2 heats of adsorption are generally too small to promote significant adsorption under desired storage conditions. Increasing the H2–framework interaction energy is a prominent goal of current MOF design. Hydrogen binds to MOFs through a variety of interactions, such as dispersion, charge–induced-dipole, charge–quadrupole, and even chemical bonding. To date, these interactions have been enhanced by incorporating strongly charged groups into the MOF structures, but the effects tend to be short-range and only effective at low loadings. In this work we report the structures and H2 storage properties of two zwitterionic MOFs. These structures feature zwitterionic characteristics arising from N-heterocyclic azolium groups in the linkers and negatively charged Zn2(CO2)5 nodes. These groups exhibit net charges of +0.5 and −1.0, respectively, and interact strongly with the H2 quadrupole. Isosteric heats of adsorption of up to 7.0 kJ mol−1 are observed in these zwitterionic MOFs.
Co-reporter:Huong Giang T. Nguyen, Mitchell H. Weston, Amy A. Sarjeant, Daniel M. Gardner, Zhi An, Raanan Carmieli, Michael R. Wasielewski, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
Crystal Growth & Design 2013 Volume 13(Issue 8) pp:3528-3534
Publication Date(Web):June 25, 2013
DOI:10.1021/cg400500t
Through a combination of protecting groups, postsynthesis deprotection, and postsynthesis metallation, a homogeneously inaccessible, single-site vanadyl(monocatecholate) moiety can be incorporated into the dipyridyl struts of a Zn-based, pillared paddlewheel MOF. The resulting MOF, which has large pores, exhibits catalytic activity in the benzylic oxidation of tetralin in the presence of tert-butylhydroperoxide.
Co-reporter:Mitchell H. Weston, Amelia A. Delaquil, Amy A. Sarjeant, Omar K. Farha, Joseph T. Hupp, and SonBinh T. Nguyen
Crystal Growth & Design 2013 Volume 13(Issue 7) pp:2938-2942
Publication Date(Web):May 3, 2013
DOI:10.1021/cg400342m
A series of isostructural noncatenated, water-stable zinc-based dipyridyl pillared-paddlewheel metal–organic frameworks (MOFs) was synthesized with tunable pore hydrophobicity. Pore hydrophobicity was engendered through dipyridyl ligands decorated with alkyl chains of varying length (methyl to hexyl). The most hydrophobic MOFs exhibited selective sorption of ethanol over water.
Co-reporter:Youn-Sang Bae, Brad G. Hauser, Yamil J. Colón, Joseph T. Hupp, Omar K. Farha, Randall Q. Snurr
Microporous and Mesoporous Materials 2013 Volume 169() pp:176-179
Publication Date(Web):15 March 2013
DOI:10.1016/j.micromeso.2012.11.013
Separation of Xe/Kr mixtures was studied in two copper-paddlewheel metal-organic framework materials, MOF-505 and HKUST-1. For MOF-505, which has small pores with strong adsorption sites, high Xe/Kr selectivities (9–10) are obtained from breakthrough measurements and grand canonical Monte Carlo (GCMC) simulations. The consistent results from both techniques suggest that MOF-505 is a promising candidate for Xe/Kr separation. For HKUST-1, which has small octahedral pores, only modest Xe/Kr selectivities (4.5) are observed from breakthrough measurements, although the GCMC simulations predicted unusually high selectivities at low loadings.Graphical abstractHighlights► MOF-505 shows high Xe/Kr selectivity from both experiments and simulations. ► The experimental selectivities for MOF-505 (9–10) are among the highest ones reported. ► HKUST-1 shows modest experimental selectivity in breakthrough measurements.
Co-reporter:Olga Karagiaridi, Marianne B. Lalonde, Wojciech Bury, Amy A. Sarjeant, Omar K. Farha, and Joseph T. Hupp
Journal of the American Chemical Society 2012 Volume 134(Issue 45) pp:18790-18796
Publication Date(Web):October 22, 2012
DOI:10.1021/ja308786r
A zeolitic imidazolate framework material of SOD topology possessing primarily unsubstituted imidazolate (im) linkers has been synthesized via solvent-assisted linker exchange (SALE) of ZIF-8. The structure of the new material, SALEM-2, has been confirmed through 1H NMR and powder and single-crystal X-ray diffraction. SALEM-2 is the first example of a porous Zn(im)2 ZIF possessing a truly zeolitic topology that can be obtained in bulk quantities. Upon treatment with n-butyllithium, the open analogue exhibits Brønsted base catalysis that cannot be accomplished by the parent material ZIF-8. Additionally, it displays a different size cutoff for uptake and release of molecular guests than does ZIF-8.
Co-reporter:Ho-Jin Son ; Shengye Jin ; Sameer Patwardhan ; Sander J. Wezenberg ; Nak Cheon Jeong ; Monica So ; Christopher E. Wilmer ; Amy A. Sarjeant ; George C. Schatz ; Randall Q. Snurr ; Omar K. Farha ; Gary P. Wiederrecht ;Joseph T. Hupp
Journal of the American Chemical Society 2012 Volume 135(Issue 2) pp:862-869
Publication Date(Web):December 18, 2012
DOI:10.1021/ja310596a
Given that energy (exciton) migration in natural photosynthesis primarily occurs in highly ordered porphyrin-like pigments (chlorophylls), equally highly ordered porphyrin-based metal–organic frameworks (MOFs) might be expected to exhibit similar behavior, thereby facilitating antenna-like light-harvesting and positioning such materials for use in solar energy conversion schemes. Herein, we report the first example of directional, long-distance energy migration within a MOF. Two MOFs, namely F-MOF and DA-MOF that are composed of two Zn(II) porphyrin struts [5,15-dipyridyl-10,20-bis(pentafluorophenyl)porphinato]zinc(II) and [5,15-bis[4-(pyridyl)ethynyl]-10,20-diphenylporphinato]zinc(II), respectively, were investigated. From fluorescence quenching experiments and theoretical calculations, we find that the photogenerated exciton migrates over a net distance of up to ∼45 porphyrin struts within its lifetime in DA-MOF (but only ∼3 in F-MOF), with a high anisotropy along a specific direction. The remarkably efficient exciton migration in DA-MOF is attributed to enhanced π-conjugation through the addition of two acetylene moieties in the porphyrin molecule, which leads to greater Q-band absorption intensity and much faster exciton-hopping (energy transfer between adjacent porphyrin struts). The long distance and directional energy migration in DA-MOF suggests promising applications of this compound or related compounds in solar energy conversion schemes as an efficient light-harvesting and energy-transport component.
Co-reporter:Omar K. Farha ; Ibrahim Eryazici ; Nak Cheon Jeong ; Brad G. Hauser ; Christopher E. Wilmer ; Amy A. Sarjeant ; Randall Q. Snurr ; SonBinh T. Nguyen ; A. Özgür Yazaydın ;Joseph T. Hupp
Journal of the American Chemical Society 2012 Volume 134(Issue 36) pp:15016-15021
Publication Date(Web):August 20, 2012
DOI:10.1021/ja3055639
We have synthesized, characterized, and computationally simulated/validated the behavior of two new metal–organic framework (MOF) materials displaying the highest experimental Brunauer–Emmett–Teller (BET) surface areas of any porous materials reported to date (∼7000 m2/g). Key to evacuating the initially solvent-filled materials without pore collapse, and thereby accessing the ultrahigh areas, is the use of a supercritical CO2 activation technique. Additionally, we demonstrate computationally that by shifting from phenyl groups to “space efficient” acetylene moieties as linker expansion units, the hypothetical maximum surface area for a MOF material is substantially greater than previously envisioned (∼14600 m2/g (or greater) versus ∼10500 m2/g).
Co-reporter:Omar K. Farha ; Christopher E. Wilmer ; Ibrahim Eryazici ; Brad G. Hauser ; Philip A. Parilla ; Kevin O’Neill ; Amy A. Sarjeant ; SonBinh T. Nguyen ; Randall Q. Snurr ;Joseph T. Hupp
Journal of the American Chemical Society 2012 Volume 134(Issue 24) pp:9860-9863
Publication Date(Web):June 7, 2012
DOI:10.1021/ja302623w
We have synthesized, characterized, and computationally validated the high Brunauer–Emmett–Teller surface area and hydrogen uptake of a new, noncatenating metal–organic framework (MOF) material, NU-111. Our results imply that replacing the phenyl spacers of organic linkers with triple-bond spacers is an effective strategy for boosting molecule-accessible gravimetric surface areas of MOFs and related high-porosity materials.
Co-reporter:John M. Roberts ; Branden M. Fini ; Amy A. Sarjeant ; Omar K. Farha ; Joseph T. Hupp ;Karl A. Scheidt
Journal of the American Chemical Society 2012 Volume 134(Issue 7) pp:3334-3337
Publication Date(Web):January 31, 2012
DOI:10.1021/ja2108118
A new urea-containing metal–organic framework (MOF) was synthesized to act as a heterogeneous catalyst. Ureas are well-known for self-recognition and aggregation behavior, resulting in loss of catalytic competency. The catalyst spatial isolation achievable in a porous MOF environment suggests a potentially general solution. The combination of a symmetrical urea tetracarboxylate strut, 4,4′-bipyridine, and Zn(NO3)2·6H2O under solvothermal conditions afforded a new microporous MOF (NU-601). This material is indeed an effective hydrogen-bond-donor catalyst for Friedel–Crafts reactions between pyrroles and nitroalkenes, whereas a homogeneous urea is much less competent. The higher rates of reaction of small substrates relative to larger ones with NU-601 strongly suggest that catalysis primarily occurs within the pores of this new material rather than on its exterior. To the best of our knowledge, this approach is the first example of specific engineering of successful hydrogen-bonding catalysis into a MOF material.
Co-reporter:Marianne B. Lalonde, Omar K. Farha, Karl A. Scheidt, and Joseph T. Hupp
ACS Catalysis 2012 Volume 2(Issue 8) pp:1550
Publication Date(Web):July 3, 2012
DOI:10.1021/cs300260f
Metal imidazolates, an important class of constructs in metal–organic framework chemistry, are shown here to be precursors to N-heterocyclic carbene-like catalysts. By using n-butyl lithium to deprotonate tripodal imidazolate framework-1 (TIF-1), N-heterocyclic carbene (NHC) sites can be exposed. These sites are found to be remarkably competent as Brønsted-base-type NHC catalysts. An α,β-unsaturated ketone was converted to the corresponding benzyl ether with benzyl alcohol at a faster rate and in higher yield than with a traditional homogeneous NHC catalyst (1,3-bis-(2,4,6-trimethylphenyl)imidazole)), despite lower overall loading. Varying the size of the alcohol in the conjugate addition reaction yielded no change in reaction rate, even when the size of the alcohol exceeded the diameter of the MOF pores, suggesting that catalysis occurs exclusively on the surface of the MOF crystals, as opposed to within the framework pores.Keywords: conjugate addition; ethers; metal organic frameworks; N-heterocyclic carbenes;
Co-reporter:Mitchell H. Weston, Omar K. Farha, Brad G. Hauser, Joseph T. Hupp, and SonBinh T. Nguyen
Chemistry of Materials 2012 Volume 24(Issue 7) pp:1292
Publication Date(Web):January 31, 2012
DOI:10.1021/cm2034646
Robust catechol-functionalized porous organic polymers (POPs) with tunable porosities (560–1050 m2/g) and degrees of functionalization were synthesized using a cobalt-catalyzed acetylene trimerization (CCAT) strategy. Post-synthesis metalation can be readily carried out with a wide range of metal precursors (CuII, MgII, and MnII salts and complexes), resulting in metalated POPs with enhanced heat of hydrogen adsorptions compared to the starting nonmetalated materials.Keywords: hydrogen storage; metal catecholates; porous organic polymers;
Co-reporter:Olga Karagiaridi, Wojciech Bury, Amy A. Sarjeant, Charlotte L. Stern, Omar K. Farha and Joseph T. Hupp
Chemical Science 2012 vol. 3(Issue 11) pp:3256-3260
Publication Date(Web):07 Aug 2012
DOI:10.1039/C2SC20558K
Herein, we present the first examples of solvent-assisted linker exchange (SALE) in zeolitic imidazolate frameworks (ZIFs). By exposing the ZIF CdIF-4 to excess solutions of 2-nitroimidazole and 2-methylimidazole under solvothermal conditions, we were able to obtain a previously reported ZIF CdIF-9 in high yield, as well as synthesize a new ZIF, Solvent-Assisted Linker-Exchanged Material-1 (SALEM-1). The parent and daughter ZIFs are isostructural (RHO zeolitic topology) and highly porous. Despite the high thermal and chemical stability of ZIFs, single crystal-to-single crystal linker exchange appears to be a suitable tool for the modification and functionalization of these materials. We anticipate that the addition of SALE to the arsenal of known synthetic techniques for ZIFs will significantly facilitate the quest to obtain interesting and useful ZIF compounds, including compounds that cannot be synthesized directly.
Co-reporter:Huong Giang T. Nguyen, Mitchell H. Weston, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
CrystEngComm 2012 vol. 14(Issue 12) pp:4115-4118
Publication Date(Web):01 Mar 2012
DOI:10.1039/C2CE06666A
A vanadyl(monocatecholate)-decorated metal-organic framework was synthesized using two sequential post-synthesis modifications. This material is catalytically active for the oxidation of organo-sulfide. In contrast to the homogeneous control catalyst, it can be tuned to be selective for the sulfoxide product using tert-butyl hydroperoxide as oxidant.
Co-reporter:Ibrahim Eryazici, Omar K. Farha, Brad G. Hauser, A. Özgür Yazaydın, Amy A. Sarjeant, SonBinh T. Nguyen, and Joseph T. Hupp
Crystal Growth & Design 2012 Volume 12(Issue 3) pp:1075-1080
Publication Date(Web):January 27, 2012
DOI:10.1021/cg201520z
Two noninterpenetrated MOFs with strikingly different structures, NU-108-Cu and NU-108-Zn, were prepared from a single hexa-carboxylated ligand. NU-108-Cu contains paddlewheel-coordinated copper ions as nodes and is based on a 3,24 network associated with an inherently noncatenating rht-topology. Modifications introduced in the hexa-carboxylated struts (uniquely placed phenyl spacers) lead to substantial changes in pore sizes, relative to those found in other MOFs based on 3,24 networks and paddlewheel-coordinated copper ions. NU-108-Zn features a new net based on (3,3,6)-connecter and octadehral Zn4O nodes in which all struts lie in a–b planes.
Co-reporter:Gregory W. Peterson;Bryan Schindler
Journal of Porous Materials 2012 Volume 19( Issue 2) pp:261-266
Publication Date(Web):2012 April
DOI:10.1007/s10934-011-9468-7
A previously described porous organic polymer (NU-POP-1) was evaluated against four representative chemical threats: ammonia, cyanogen chloride, sulfur dioxide, and octane. Ammonia, cyanogen chloride, and sulfur dioxide are examples of toxic industrial chemicals (TICs) spanning the range from highly basic to strong-acid forming substances, while octane is used to assess physical adsorption capacity. Experiments were carried out using a microbreakthrough test apparatus, which measures the adsorption capacity at saturation and gives an indication of the strength of adsorption. The NU-POP-1 material exhibited substantial removal capabilities against the majority of the toxic chemicals, with capacities as high as or better than an activated, impregnated carbon. The ability to remove the highly volatile toxic chemicals ammonia and cyanogen chloride was intriguing, as these chemicals typically require reactive moieities for removal. The present work presents a benchmark for toxic chemical removal, and future work will focus on incorporating functional groups targeting the toxic chemicals of interest.
Co-reporter:Chang Yeon Lee, Omar K. Farha, Bong Jin Hong, Amy A. Sarjeant, SonBinh T. Nguyen, and Joseph T. Hupp
Journal of the American Chemical Society 2011 Volume 133(Issue 40) pp:15858-15861
Publication Date(Web):September 14, 2011
DOI:10.1021/ja206029a
A pillared-paddlewheel type metal–organic framework material featuring bodipy- and porphyrin-based struts, and capable of harvesting light across the entire visible spectrum, has been synthesized. Efficient—essentially quantitative—strut-to-strut energy transfer (antenna behavior) was observed for the well-organized donor–acceptor assembly consituting the ordered MOF structure.
Co-reporter:Omar K. Farha ; Abraham M. Shultz ; Amy A. Sarjeant ; SonBinh T. Nguyen ;Joseph T. Hupp
Journal of the American Chemical Society 2011 Volume 133(Issue 15) pp:5652-5655
Publication Date(Web):March 29, 2011
DOI:10.1021/ja111042f
On account of their structural similarity to cofactors found in many metallo-enzymes, metalloporphyrins are obvious potential building blocks for catalytically active, metal−organic framework (MOF) materials. While numerous porphyrin-based MOFs have already been described, versions featuring highly accessible active sites and permanent microporosity are remarkably scarce. Indeed, of the more than 70 previously reported porphyrinic MOFs, only one has been shown to be both permanently microporous and contain internally accessible active sites for chemical catalysis. Attempts to generalize the design approach used in this single successful case have failed. Reported here, however, is the synthesis of an extended family of MOFs that directly incorporate a variety of metalloporphyrins (specifically Al3+, Zn2+, Pd2+, Mn3+, and Fe3+ complexes). These robust porphyrinic materials (RPMs) feature large channels and readily accessible active sites. As an illustrative example, one of the manganese-containing RPMs is shown to be catalytically competent for the oxidation of alkenes and alkanes.
Co-reporter:Nak Cheon Jeong ; Bappaditya Samanta ; Chang Yeon Lee ; Omar K. Farha ;Joseph T. Hupp
Journal of the American Chemical Society 2011 Volume 134(Issue 1) pp:51-54
Publication Date(Web):December 12, 2011
DOI:10.1021/ja2110152
HKUST-1, a metal–organic framework (MOF) material containing CuII-paddlewheel-type nodes and 1,3,5-benzenetricarboxylate struts, features accessible CuII sites to which solvent or other desired molecules can be intentionally coordinated. As part of a broader investigation of ionic conductivity in MOFs, we unexpectedly observed substantial proton conductivity with the “as synthesized” version of this material following sorption of methanol. Although HKUST-1 is neutral, coordinated water molecules are rendered sufficiently acidic by CuII to contribute protons to pore-filling methanol molecules and thereby enhance the alternating-current conductivity. At ambient temperature, the chemical identities of the node-coordinated and pore-filling molecules can be independently varied, thus enabling the proton conductivity to be reversibly modulated. The proton conductivity of HKUST-1 was observed to increase by ∼75-fold, for example, when node-coordinated acetonitrile molecules were replaced by water molecules. In contrast, the conductivity became almost immeasurably small when methanol was replaced by hexane as the pore-filling solvent.
Co-reporter:Omar K. Farha ; Christos D. Malliakas ; Mercouri G. Kanatzidis ;Joseph T. Hupp
Journal of the American Chemical Society 2009 Volume 132(Issue 3) pp:950-952
Publication Date(Web):December 29, 2009
DOI:10.1021/ja909519e
Metal−organic frameworks (MOFs), a hybrid class of materials comprising inorganic nodes and organic struts, have potential application in many areas due to their high surface areas and uniform pores and channels. One of the key challenges to be overcome in MOF synthesis is the strong propensity for catenation (growth of multiple independent networks within a given crystal), as catenation reduces cavity sizes and diminishes porosity. Here we demonstrate that rational design of organic building blocks, which act as strut-impervious scaffolds, can be exploited to generate highly desired noncatenated materials in a controlled fashion.
Co-reporter:Timothy C. Wang; Wojciech Bury; Diego A. Gómez-Gualdrón; Nicolaas A. Vermeulen; Joseph E. Mondloch; Pravas Deria; Kainan Zhang; Peyman Z. Moghadam; Amy A. Sarjeant; Randall Q. Snurr; J. Fraser Stoddart; Joseph T. Hupp
Journal of the American Chemical Society () pp:
Publication Date(Web):February 27, 2015
DOI:10.1021/ja512973b
An isoreticular series of metal–organic frameworks (MOFs) with the ftw topology based on zirconium oxoclusters and tetracarboxylate linkers with a planar core (NU-1101 through NU-1104) has been synthesized employing a linker expansion approach. In this series, NU-1103 has a pore volume of 2.91 cc g–1 and a geometrically calculated surface area of 5646 m2 g–1, which is the highest value reported to date for a zirconium-based MOF and among the largest that have been reported for any porous material. Successful activation of the MOFs was proven based on the agreement of pore volumes and BET areas obtained from simulated and experimental isotherms. Critical for practical applications, NU-1103 combines for the first time ultrahigh surface area and water stability, where this material retained complete structural integrity after soaking in water. Pressure range selection for the BET calculations on these materials was guided by the four so-called “consistency criteria”. The experimental BET area of NU-1103 was 6550 m2 g–1. Insights obtained from molecular simulation suggest that, as a consequence of pore-filling contamination, the BET method overestimates the monolayer loading of NU-1103 by ∼16%.
Co-reporter:Yangyang Liu, Rachel C. Klet, Joseph T. Hupp and Omar Farha
Chemical Communications 2016 - vol. 52(Issue 50) pp:NaN7809-7809
Publication Date(Web):2016/05/19
DOI:10.1039/C6CC03727E
Seven Zr/Hf-based MOFs with different degrees of defects were obtained by modulating the synthetic conditions. The number of missing linkers in these MOFs was calculated based on potentiometric acid–base titration. The number of defects was found to correlate quantitatively with the catalytic activity of UiO-type MOFs for an acid-catalyzed epoxide ring-opening reaction. More importantly, we were able to identify a MOF with inherent defective Zr6 nodes, which showed great activity and regio-selectivity for the epoxide ring-opening reaction.
Co-reporter:J. R. Avila, A. W. Peters, Zhanyong Li, M. A. Ortuño, A. B. F. Martinson, C. J. Cramer, J. T. Hupp and O. K. Farha
Dalton Transactions 2017 - vol. 46(Issue 18) pp:NaN6128-6128
Publication Date(Web):2017/04/28
DOI:10.1039/C7DT90077E
Correction for ‘Atomic layer deposition of Cu(I) oxide films using Cu(II) bis(dimethylamino-2-propoxide) and water’ by J. R. Avila, et al., Dalton Trans., 2017, DOI: 10.1039/c6dt02572b.
Co-reporter:N. Scott Bobbitt, Matthew L. Mendonca, Ashlee J. Howarth, Timur Islamoglu, Joseph T. Hupp, Omar K. Farha and Randall Q. Snurr
Chemical Society Reviews 2017 - vol. 46(Issue 11) pp:NaN3385-3385
Publication Date(Web):2017/03/27
DOI:10.1039/C7CS00108H
Owing to the vast diversity of linkers, nodes, and topologies, metal–organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal–organic frameworks.
Co-reporter:Mizuho Yabushita, Peng Li, Hirokazu Kobayashi, Atsushi Fukuoka, Omar K. Farha and Alexander Katz
Chemical Communications 2016 - vol. 52(Issue 79) pp:NaN11794-11794
Publication Date(Web):2016/09/01
DOI:10.1039/C6CC05864G
Metal–organic framework NU-1000 selectively adsorbs furanics, while completely excluding the adsorption of monomeric sugars from the same aqueous mixture. The highly refined degree of molecular recognition exhibited by NU-1000 is exemplified with it selectively adsorbing 5-hydroxymethylfurfural, even in the presence of up to a 300-fold excess of glucose in solution.
Co-reporter:J. R. Avila, A. W. Peters, Zhanyong Li, M. A. Ortuño, A. B. F. Martinson, C. J. Cramer, J. T. Hupp and O. K. Farha
Dalton Transactions 2017 - vol. 46(Issue 18) pp:NaN5795-5795
Publication Date(Web):2017/04/03
DOI:10.1039/C6DT02572B
To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(II), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant. Between 110 and 175 °C, a growth rate of 0.12 ± 0.02 Å per cycle was measured using an in situ quartz crystal microbalance (QCM). X-ray photoelectron spectroscopy (XPS) confirms the growth of metal–oxide films featuring Cu(I).
Co-reporter:Carla F. Pereira, Ashlee J. Howarth, Nicolaas A. Vermeulen, Filipe A. Almeida Paz, João P. C. Tomé, Joseph T. Hupp and Omar K. Farha
Inorganic Chemistry Frontiers 2017 - vol. 1(Issue 6) pp:NaN1199-1199
Publication Date(Web):2017/01/30
DOI:10.1039/C6QM00364H
Solvent-assisted linker exchange (SALE) is performed on the Zr-based metal–organic framework (MOF), UiO-66, to exchange benzene-1,4-dicarboxylate with benzene-1,4-dihydroxamate linkers. Characterization of the material before and after SALE is performed using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), nitrogen adsorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The stability of the parent and daughter material is evaluated at pH 1 and 12 and the structural integrity evaluated by PXRD, mass balance and porosity measurements.
Co-reporter:Zhanyong Li, Aaron W. Peters, Jian Liu, Xuan Zhang, Neil M. Schweitzer, Joseph T. Hupp and Omar K. Farha
Inorganic Chemistry Frontiers 2017 - vol. 4(Issue 5) pp:NaN824-824
Publication Date(Web):2017/03/09
DOI:10.1039/C7QI00056A
Ni(II) ions have been deposited on the Zr6 nodes of a metal–organic framework (MOF), UiO-66, via an ALD-like process (ALD = atomic layer deposition). By varying the number of ALD cycles, three Ni-decorated UiO-66 materials were synthesized. A suite of physical methods has been used to characterize these materials, indicating structural and high-surface-area features of the parent MOF are retained. Elemental analysis via X-ray photoelectron spectroscopy (XPS) indicates that the anchored Ni ions are mainly on surface and near-surface MOF defect sites. Upon activation, all three materials are catalytic for ethylene hydrogenation, but their catalytic activities significantly vary, with the largest clusters displaying the highest per-nickel-atom activity. The study highlights the ease and effectiveness of ALD in MOFs (AIM) for synthesizing, specifically, UiO-66-supported NiyOx catalysts.
Co-reporter:Krunoslav Užarević, Timothy C. Wang, Su-Young Moon, Athena M. Fidelli, Joseph T. Hupp, Omar K. Farha and Tomislav Friščić
Chemical Communications 2016 - vol. 52(Issue 10) pp:NaN2136-2136
Publication Date(Web):2015/12/08
DOI:10.1039/C5CC08972G
We develop the first mechanochemical and solvent-free routes for zirconium metal–organic frameworks, making the frameworks UiO-66 and UiO-66-NH2 accessible on the gram scale without strong acids, high temperatures or excess reactants. The frameworks form either by milling, or spontaneous self-assembly by simply exposing solid mixtures of reactants to organic vapour. The generated frameworks exhibit high porosity and catalytic activity in the hydrolysis of model nerve agents, on par with their solvothermally generated counterparts.
Co-reporter:Monica C. So, M. Hassan Beyzavi, Rohan Sawhney, Osama Shekhah, Mohamed Eddaoudi, Salih S. Al-Juaid, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 - vol. 51(Issue 1) pp:NaN88-88
Publication Date(Web):2014/10/17
DOI:10.1039/C4CC05727A
Herein, we demonstrate the robustness of layer-by-layer (LbL)-assembled, pillared-paddlewheel-type MOF films toward conversion to new or modified MOFs via solvent-assisted linker exchange (SALE) and post-assembly linker metalation. Further, we show that LbL synthesis can afford MOFs that have proven inaccessible through other de novo strategies.
Co-reporter:Peng Li, Rachel C. Klet, Su-Young Moon, Timothy C. Wang, Pravas Deria, Aaron W. Peters, Benjamin M. Klahr, Hea-Jung Park, Salih S. Al-Juaid, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 - vol. 51(Issue 54) pp:NaN10928-10928
Publication Date(Web):2015/06/11
DOI:10.1039/C5CC03398E
The synthesis of nano-sized particles of NU-1000 (length from 75 nm to 1200 nm) and PCN-222/MOF-545 (length from 350 nm to 900 nm) is reported. The catalytic hydrolysis of methyl paraoxon was investigated as a function of NU-1000 crystallite size and a significant enhancement in the rate was observed for the nano-sized crystals compared to microcrystals.
Co-reporter:Pravas Deria, Song Li, Hongda Zhang, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 - vol. 51(Issue 62) pp:NaN12481-12481
Publication Date(Web):2015/07/06
DOI:10.1039/C5CC04808G
CO2 capture is essential for reducing the carbon footprint of coal-fired power plants. Here we show, both experimentally and computationally, a new design strategy for capturing CO2 in nanoporous adsorbents. The approach involves ‘complementary organic motifs’ (COMs), which have a precise alignment of charge densities that is complementary to the CO2 quadrupole. Two promising COMs were post-synthetically incorporated into a robust metal–organic framework (MOF) material using solvent-assisted ligand incorporation (SALI). We demonstrate that these COM-functionalized MOFs exhibit high capacity and selectivity for CO2 relative to other reported motifs.
Co-reporter:Idan Hod, Omar K. Farha and Joseph T. Hupp
Chemical Communications 2016 - vol. 52(Issue 8) pp:NaN1708-1708
Publication Date(Web):2015/12/15
DOI:10.1039/C5CC09695B
Herein we demonstrate the use of host–guest chemistry to modulate rates of charge transport in metal–organic framework (MOF) films. The kinetics of site-to-site of charge hopping and, in turn, the overall redox conductivity, of a ferrocene-modified MOF can be altered by up to 30-fold by coupling electron exchange to the oxidation-state-dependent formation of inclusion complexes between cyclodextrin and channel-tethered metallocenes.
Co-reporter:Mizuho Yabushita, Peng Li, Varinia Bernales, Hirokazu Kobayashi, Atsushi Fukuoka, Laura Gagliardi, Omar K. Farha and Alexander Katz
Chemical Communications 2016 - vol. 52(Issue 44) pp:NaN7097-7097
Publication Date(Web):2016/05/03
DOI:10.1039/C6CC03266D
Metal–organic framework (MOF) material NU-1000 adsorbs dimers cellobiose and lactose from aqueous solution, in amounts exceeding 1250 mg gNU-1000−1 while completely excluding the adsorption of the monomer glucose, even in a competitive mode with cellobiose. The MOF also discriminates between dimers consisting of α and β linkages, showing no adsorption of maltose. Electronic structure calculations demonstrate that key to this selective molecular recognition is the number of favorable CH–π interactions made by the sugar with pyrene units of the MOF.
Co-reporter:Monica C. So, Gary P. Wiederrecht, Joseph E. Mondloch, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2015 - vol. 51(Issue 17) pp:NaN3510-3510
Publication Date(Web):2015/01/12
DOI:10.1039/C4CC09596K
A critical review of the emerging field of MOFs for photon collection and subsequent energy transfer is presented. Discussed are examples involving MOFs for (a) light harvesting, using (i) MOF-quantum dots and molecular chromophores, (ii) chromophoric MOFs, and (iii) MOFs with light-harvesting properties, and (b) energy transfer, specifically via the (i) Förster energy transfer and (ii) Dexter exchange mechanism.
Co-reporter:Yang Peng, Gadipelli Srinivas, Christopher E. Wilmer, Ibrahim Eryazici, Randall Q. Snurr, Joseph T. Hupp, Taner Yildirim and Omar K. Farha
Chemical Communications 2013 - vol. 49(Issue 29) pp:NaN2994-2994
Publication Date(Web):2013/02/21
DOI:10.1039/C3CC40819A
We show that the MOF NU-111 exhibits equally high volumetric and gravimetric methane uptake values, both within ≈75% of the DOE targets at 300 K. Upon reducing the temperature to 270 K, the uptake increases to 0.5 g g−1 and 284 cc(STP) per cc at 65 bar. Adsorption of CO2 and H2 is also reported. Simulated isotherms are in excellent agreement with those obtained from experiments.
Co-reporter:Mitchell H. Weston, Gregory W. Peterson, Matthew A. Browe, Paulette Jones, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2013 - vol. 49(Issue 29) pp:NaN2997-2997
Publication Date(Web):2013/02/12
DOI:10.1039/C3CC40475G
Porous organic polymers bearing metal–catecholate groups were evaluated for their ability to remove airborne ammonia, cyanogen chloride, sulphur dioxide, and octane by micro-breakthrough analysis. For ammonia, the metal–catecholate materials showed remarkable uptake under humid conditions.
Co-reporter:Pravas Deria, Wojciech Bury, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2014 - vol. 50(Issue 16) pp:NaN1968-1968
Publication Date(Web):2014/01/09
DOI:10.1039/C3CC48562E
Solvent-assisted ligand incorporation (SALI) was utilized to efficiently insert various carboxylate-derived functionalities into the Zr-based metal–organic framework NU-1000 as charge compensating moieties strongly bound to the Zr6 nodes. SALI-derived functionalities are accessible for further chemical reactions such as click chemistry, imine condensation and pyridine quaternization.
Co-reporter:Joseph E. Mondloch, Michael J. Katz, Nora Planas, David Semrouni, Laura Gagliardi, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2014 - vol. 50(Issue 64) pp:NaN8946-8946
Publication Date(Web):2014/06/30
DOI:10.1039/C4CC02401J
Metal–organic frameworks (MOFs) built up from Zr6-based nodes and multi-topic carboxylate linkers have attracted attention due to their favourable thermal and chemical stability. However, the hydrolytic stability of some of these Zr6-based MOFs has recently been questioned. Herein we demonstrate that two Zr6-based frameworks, namely UiO-67 and NU-1000, are stable towards linker hydrolysis in H2O, but collapse during activation from H2O. Importantly, this framework collapse can be overcome by utilizing solvent-exchange to solvents exhibiting lower capillary forces such as acetone.
Co-reporter:Michael J. Katz, Zachary J. Brown, Yamil J. Colón, Paul W. Siu, Karl A. Scheidt, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2013 - vol. 49(Issue 82) pp:NaN9451-9451
Publication Date(Web):2013/09/06
DOI:10.1039/C3CC46105J
A scalable, reproducible method of synthesizing UiO-66- and UiO-67-type MOFs, entailing the addition of HCl to the reaction mixture, has been investigated. The new protocol requires a fraction of the time of previously reported procedures, yields exceptional porosities, and works with a range of linkers.
Co-reporter:Paul W. Siu, Zachary J. Brown, Omar K. Farha, Joseph T. Hupp and Karl A. Scheidt
Chemical Communications 2013 - vol. 49(Issue 93) pp:NaN10922-10922
Publication Date(Web):2013/10/10
DOI:10.1039/C3CC47177B
A hydrogen-bond donating MOF catalyst based on the UiO-67 framework, containing both urea-functionalized dicarboxylate and biphenyl-4,4′-dicarboxylate struts, was synthesized by a de novo route. The mixed strut framework has larger pore sizes and improved catalytic activity for Henry reactions than the pure strut analogue, which contains only the urea-functionalized dicarboxylate linker.
Co-reporter:Michael J. Katz, Su-Young Moon, Joseph E. Mondloch, M. Hassan Beyzavi, Casey J. Stephenson, Joseph T. Hupp and Omar K. Farha
Chemical Science (2010-Present) 2015 - vol. 6(Issue 4) pp:NaN2291-2291
Publication Date(Web):2015/02/24
DOI:10.1039/C4SC03613A
The hydrolysis of nerve agents is of primary concern due to the severe toxicity of these agents. Using a MOF-based catalyst (UiO-66), we have previously demonstrated that the hydrolysis can occur with relatively fast half-lives of 50 minutes. However, these rates are still prohibitively slow to be efficiently utilized for some practical applications (e.g., decontamination wipes used to clean exposed clothing/skin/vehicles). We thus turned our attention to derivatives of UiO-66 in order to probe the importance of functional groups on the hydrolysis rate. Three UiO-66 derivatives were explored; UiO-66-NO2 and UiO-66-(OH)2 showed little to no change in hydrolysis rate. However, UiO-66-NH2 showed a 20 fold increase in hydrolysis rate over the parent UiO-66 MOF. Half-lives of 1 minute were observed with this MOF. In order to probe the role of the amino moiety, we turned our attention to UiO-67, UiO-67-NMe2 and UiO-67-NH2. In these MOFs, the amino moiety is in close proximity to the zirconium node. We observed that UiO-67-NH2 is a faster catalyst than UiO-67 and UiO-67-NMe2. We conclude that the role of the amino moiety is to act as a proton-transfer agent during the catalytic cycle and not to hydrogen bond or to form a phosphorane intermediate.
Co-reporter:Ryan K. Totten, Laura L. Olenick, Ye-Seong Kim, Sanjiban Chakraborty, Mitchell H. Weston, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science (2010-Present) 2014 - vol. 5(Issue 2) pp:NaN787-787
Publication Date(Web):2013/10/09
DOI:10.1039/C3SC52010B
Porous organic polymers (POPs) with tunable pore volumes and surface areas can be made from a series of SnIV(porphyrins) functionalized with labile, bulky trans-diaxial ligands. Varying the ligand size allows for the tuning of the micropore volume while supercritical CO2 processing resulted in excellent enhancements of the total pore volumes.
Co-reporter:Shinya Takaishi, Erica J. DeMarco, Michael J. Pellin, Omar K. Farha and Joseph T. Hupp
Chemical Science (2010-Present) 2013 - vol. 4(Issue 4) pp:NaN1513-1513
Publication Date(Web):2012/12/07
DOI:10.1039/C2SC21516K
Using recently reported robust porphyrinic metal–organic framework (RPM) materials, we have examined the systematic exchange of pillaring linkers/struts as a means of accessing new versions of these materials. Dipyridyl-porphyrin Zn(II) (Zn-dipy) struts were successfully replaced by M2-dipy (M2 = 2H(+), Al(III), Sn(IV)), forming crystalline solid solutions of Zn(Zn1−xMx)-RPM in variable ratios. In addition, post-synthetic metallation was demonstrated using Zn2H-RPM, again with retention of crystallinity. We examined catalytic activity for an epoxide ring-opening reaction with a series of ZnM2-RPMs. The catalytic activity depends strongly on the identity of the metal ion present in the dipyridyl-porphyrin unit.
Co-reporter:Pravas Deria, Yongchul G. Chung, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Chemical Science (2010-Present) 2015 - vol. 6(Issue 9) pp:NaN5176-5176
Publication Date(Web):2015/07/01
DOI:10.1039/C5SC01784J
Water stability in metal–organic frameworks (MOFs) is critical for several practical applications. While water instability is mainly thought to stem from linker hydrolysis, MOFs with strong, hydrolysis-resistant metal-linker bonds can be susceptible to damage by capillary forces, which cause cavities and channels to collapse during activation from water. This study utilizes metal node functionalization as a strategy to create vapor-stable and recyclable MOFs.
Co-reporter:Olga Karagiaridi, Wojciech Bury, Amy A. Sarjeant, Charlotte L. Stern, Omar K. Farha and Joseph T. Hupp
Chemical Science (2010-Present) 2012 - vol. 3(Issue 11) pp:NaN3260-3260
Publication Date(Web):2012/08/07
DOI:10.1039/C2SC20558K
Herein, we present the first examples of solvent-assisted linker exchange (SALE) in zeolitic imidazolate frameworks (ZIFs). By exposing the ZIF CdIF-4 to excess solutions of 2-nitroimidazole and 2-methylimidazole under solvothermal conditions, we were able to obtain a previously reported ZIF CdIF-9 in high yield, as well as synthesize a new ZIF, Solvent-Assisted Linker-Exchanged Material-1 (SALEM-1). The parent and daughter ZIFs are isostructural (RHO zeolitic topology) and highly porous. Despite the high thermal and chemical stability of ZIFs, single crystal-to-single crystal linker exchange appears to be a suitable tool for the modification and functionalization of these materials. We anticipate that the addition of SALE to the arsenal of known synthetic techniques for ZIFs will significantly facilitate the quest to obtain interesting and useful ZIF compounds, including compounds that cannot be synthesized directly.
Co-reporter:Pravas Deria, Joseph E. Mondloch, Olga Karagiaridi, Wojciech Bury, Joseph T. Hupp and Omar K. Farha
Chemical Society Reviews 2014 - vol. 43(Issue 16) pp:NaN5912-5912
Publication Date(Web):2014/04/11
DOI:10.1039/C4CS00067F
Metal–organic frameworks (MOFs) are hybrid porous materials with many potential applications, which intimately depend on the presence of chemical functionality either at the organic linkers and/or at the metal nodes. Functionality that cannot be introduced into MOFs directly via de novo syntheses can be accessed through post-synthesis modification (PSM) on the reactive moieties of the linkers and/or nodes without disrupting the metal–linker bonds. Even more intriguing methods that go beyond PSM are herein termed building block replacement (BBR) which encompasses (i) solvent-assisted linker exchange (SALE), (ii) non-bridging ligand replacement, and (iii) transmetalation. These one-step or tandem BBR processes involve exchanging key structural components of the MOF, which in turn should allow for the evolution of protoMOF structures (i.e., the utilization of a parent MOF as a template) to design MOFs composed of completely new components, presumably via single crystal to single crystal transformations. The influence of building block replacement on the stability and properties of MOFs will be discussed, and some insights into their mechanistic aspects are provided. Future perspectives providing a glimpse into how these techniques can lead to various unexplored areas of MOF chemistry are also presented.
Co-reporter:Ashlee J. Howarth, Timothy C. Wang, Salih S. Al-Juaid, Saadullah G. Aziz, Joseph T. Hupp and Omar K. Farha
Dalton Transactions 2016 - vol. 45(Issue 1) pp:NaN97-97
Publication Date(Web):2015/11/18
DOI:10.1039/C5DT04163E
A Zr-based MOF, NU-1000, comprised of Zr6 nodes and tetratopic pyrene-containing linkers is studied for adsorption and extraction of SO42− from water. The adsorption capacity and uptake time of SO42− in NU-1000 is determined at varying concentrations to give an overall maximum adsorption capacity of 56 mg SO42− per g of MOF. Selective adsorption of SO42− by NU-1000 in the presence of other anions as well as regeneration of the sorbent is also explored.
Co-reporter:Rachel C. Klet, Yangyang Liu, Timothy C. Wang, Joseph T. Hupp and Omar K. Farha
Journal of Materials Chemistry A 2016 - vol. 4(Issue 4) pp:NaN1485-1485
Publication Date(Web):2016/01/12
DOI:10.1039/C5TA07687K
Potentiometric acid–base titration is introduced as a method to evaluate pKa values (Brønsted acidity) of protons present in the nodes of water stable Zr6- and Hf6-based metal–organic frameworks (MOFs), including UiO-type MOFs, NU-1000, and MOF-808. pKa values were determined for the three typical types of protons present in these MOFs: μ3-OH, M–OH2, and M–OH (M = Zr, Hf). Additionally, the data was used to quantify defect sites resulting from either a surfeit or shortage of linkers in the MOFs and to provide information about the true proton topology of each material.
Co-reporter:Mitchell H. Weston, Yamil J. Colón, Youn-Sang Bae, Sergio J. Garibay, Randall Q. Snurr, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2014 - vol. 2(Issue 2) pp:NaN302-302
Publication Date(Web):2013/10/04
DOI:10.1039/C3TA12999C
A porous organic polymer decorated with high densities of copper(catecholate) groups was prepared and characterized. Single-component propylene and propane isotherms measured at ambient temperatures and ideal adsorption solution theory (IAST) calculations revealed increasing propylene/propane selectivities with increasing pressures.
Co-reporter:Marianne Lalonde, Wojciech Bury, Olga Karagiaridi, Zachary Brown, Joseph T. Hupp and Omar K. Farha
Journal of Materials Chemistry A 2013 - vol. 1(Issue 18) pp:NaN5468-5468
Publication Date(Web):2013/03/21
DOI:10.1039/C3TA10784A
The present work is a critical review of metal exchange (transmetalation) involving metal nodes and metalated struts in metal–organic frameworks. Particular emphasis is given to drawing parallels between different examples of transmetalation in order to understand the influence of coordination environment, solvents, nature of the metals and other variables on the process. We hope that the present review will be of use to those involved in the incorporation of various metal centers to create isostructural MOFs and study their properties.
Co-reporter:Michael J. Katz, Ashlee J. Howarth, Peyman Z. Moghadam, Jared B. DeCoste, Randall Q. Snurr, Joseph T. Hupp and Omar K. Farha
Dalton Transactions 2016 - vol. 45(Issue 10) pp:NaN4153-4153
Publication Date(Web):2015/09/24
DOI:10.1039/C5DT03436A
Cu-MOF-74 (also known as Cu-CPO-27) was identified as a sorbent having one of the highest densities of Cu(II) sites per unit volume. Given that Cu(II) in the framework can be thermally activated to yield a five-coordinate Cu(II) species, we identified this MOF as a potential candidate for maximal volumetric uptake of ammonia. To that end, the kinetic breakthrough of ammonia in Cu-MOF-74/Cu-CPO-27 was examined under both dry and humid conditions. Under dry conditions the MOF exhibited a respectable performance (2.6 vs. 2.9 NH3 per nm3 for the current record holder HKUST-1), and under 80% relative humidity, the MOF outperformed HKUST-1 (5.9 vs. 3.9 NH3 per nm3, respectively).
Co-reporter:Su-Young Moon, Ashlee J. Howarth, Timothy Wang, Nicolaas A. Vermeulen, Joseph T. Hupp and Omar K. Farha
Chemical Communications 2016 - vol. 52(Issue 16) pp:NaN3441-3441
Publication Date(Web):2016/01/28
DOI:10.1039/C5CC10384C
A halochromic Zr6-based metal–organic framework is synthesized using solvent-assisted linker incorporation (SALI) with NU-1000 as a platform and carboxylnaphthofluorescein as a pH sensitive ligand. The functionalized MOF can catalytically detoxify nerve agent simulants in addition to visually detecting the acidic byproduct produced during detoxification.
![[1,1'-Biphenyl]-4-carboxylic acid, 4'-[1,2,2-tris(4'-carboxy[1,1'-biphenyl]-4-yl)ethenyl]-](/data/chemimg/3723700/1610858-96-2.png)
![[1,1'-Biphenyl]-4-carboxylic acid, 4'-[1,2,2-tris(4'-carboxy[1,1'-biphenyl]-4-yl)ethenyl]-](/data/chemimg/3723700/1610858-96-2_b.png)
![[1,1'-Biphenyl]-4,4'-dicarboxylic acid, 2-[[[[3,5-bis(trifluoromethyl)phenyl]amino]carbonyl]amino]-](/data/chemimg/3718700/1486510-44-4.png)
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![Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone, 5,6,12,13-tetrachloro-2,9-di-4-pyridinyl-](/data/chemimg/3718800/1386861-24-0.png)
![Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone, 5,6,12,13-tetrachloro-2,9-di-4-pyridinyl-](/data/chemimg/3718800/1386861-24-0_b.png)
![1,3-Benzenedicarboxylic acid, 5,5',5''-[1,3,5-benzenetriyltris(1H-1,2,3-triazole-4,1-diyl)]tris-](/data/chemimg/102500/1334547-47-5.png)
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![2-Propenoic acid, 3-[5-[6-[5-[2-[4-[bis[4-(9H-carbazol-9-yl)phenyl]amino]phenyl]ethenyl]-3-hexyl-2-thienyl]dithieno[3,2-b:2',3'-d]thien-2-yl]-4-hexyl-2-](/data/chemimg/3786500/1289168-89-3.png)
![2-Propenoic acid, 3-[5-[6-[5-[2-[4-[bis[4-(9H-carbazol-9-yl)phenyl]amino]phenyl]ethenyl]-3-hexyl-2-thienyl]dithieno[3,2-b:2',3'-d]thien-2-yl]-4-hexyl-2-](/data/chemimg/3786500/1289168-89-3_b.png)
![3-Cyclobutene-1,2-dione, 3-[[3,5-bis(trifluoromethyl)phenyl]amino]-4-methoxy-](/data/chemimg/144700/1223105-85-8.png)
![3-Cyclobutene-1,2-dione, 3-[[3,5-bis(trifluoromethyl)phenyl]amino]-4-methoxy-](/data/chemimg/144700/1223105-85-8_b.png)
![1H-PYRROLE, 2-[(PENTAFLUOROPHENYL)-2H-PYRROL-2-YLIDENEMETHYL]-](http://img.cochemist.com/ccimg/630200/630110-81-5.png)
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![[1,1'-Biphenyl]-4-carboxylic acid, 4',4''',4''''',4'''''''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis-](/data/chemimg/3718100/609365-68-6.png)
![[1,1'-Biphenyl]-4-carboxylic acid, 4',4''',4''''',4'''''''-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis-](/data/chemimg/3718100/609365-68-6_b.png)
![1H-1,2,3-Triazole-4-methanamine, 1-(phenylmethyl)-N,N-bis[[1-(phenylmethyl)-1H-1,2,3-triazol-4-yl]methyl]-](/data/chemimg/72800/510758-28-8.png)
![1H-1,2,3-Triazole-4-methanamine, 1-(phenylmethyl)-N,N-bis[[1-(phenylmethyl)-1H-1,2,3-triazol-4-yl]methyl]-](/data/chemimg/72800/510758-28-8_b.png)
![Benzenamine, 4-[[tris(1-methylethyl)silyl]ethynyl]-](http://img.cochemist.com/ccimg/391200/391198-48-4.png)
![Benzenamine, 4-[[tris(1-methylethyl)silyl]ethynyl]-](http://img.cochemist.com/ccimg/391200/391198-48-4_b.png)
![1,2-Ethanediamine, N'-2-pyridinyl-N,N-bis[2-(2-pyridinylamino)ethyl]- (9CI)](/data/chemimg/3718800/293750-82-0.png)
![1,2-Ethanediamine, N'-2-pyridinyl-N,N-bis[2-(2-pyridinylamino)ethyl]- (9CI)](/data/chemimg/3718800/293750-82-0_b.png)
![Benzene, 1-[(1,1-dimethylethyl)sulfonyl]-2-iodosyl-](http://img.cochemist.com/ccimg/242500/242461-32-1.png)
![Benzene, 1-[(1,1-dimethylethyl)sulfonyl]-2-iodosyl-](http://img.cochemist.com/ccimg/242500/242461-32-1_b.png)
![N2,N2,N2',N2',N7,N7,N7',N7'-Octakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine](http://img.cochemist.com/ccimg/207800/207739-72-8.png)
![N2,N2,N2',N2',N7,N7,N7',N7'-Octakis(4-methoxyphenyl)-9,9'-spirobi[fluorene]-2,2',7,7'-tetraamine](http://img.cochemist.com/ccimg/207800/207739-72-8_b.png)
![2,2'-Bipyridine, 5,5'-bis[2-(trimethylsilyl)ethynyl]-](/data/chemimg/136800/187026-85-3.png)
![2,2'-Bipyridine, 5,5'-bis[2-(trimethylsilyl)ethynyl]-](/data/chemimg/136800/187026-85-3_b.png)
![Stannane, [2,2'-bithiophen]-5-yltributyl-](/data/chemimg/102000/162717-58-0.png)
![Stannane, [2,2'-bithiophen]-5-yltributyl-](/data/chemimg/102000/162717-58-0_b.png)
![[60]PCBA](/data/chemimg/110100/161196-26-5.png)
![[60]PCBA](/data/chemimg/110100/161196-26-5_b.png)
![[4,4',4'',4'''-(5,10,15,20-porphyrintetrayl-κ2n21,n23)tetrabenzoato(2-)]palladium](/data/chemimg/2070800/94288-44-5.png)
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![2-[DI(PROPAN-2-YL)AMINO]ETHYLSULFANYL-METHYLPHOSPHINIC ACID](http://img.cochemist.com/ccimg/73300/73207-98-4_b.png)
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![Pyridine,2,2'-[1,2-ethanediylbis(thio-2,1-ethanediyl)]bis-](http://img.cochemist.com/ccimg/64700/64691-70-9_b.png)
![[(2R)-2-[(Z)-octadec-9-enoyl]oxy-3-phosphonooxy-propyl] (Z)-octadec-9-enoate](http://img.cochemist.com/ccimg/61700/61617-08-1.png)
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![1,1'-Biphenyl, 4,4'-bis[2-(trimethylsilyl)ethynyl]-](/data/chemimg/2248300/29619-44-1_b.png)
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![Tungstate(3-),tetracosa-m-oxododecaoxo[m12-[phosphato(3-)-kO:kO:kO:kO':kO':kO':kO'':kO'':kO'':kO''':kO''':kO''']]dodeca-,hydrogen (1:3)](http://img.cochemist.com/ccimg/1400/1343-93-7_b.png)
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![Iron, chloro[5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphinato(2-)-κN21,κN22,κN23,κN24]-, (SP-5-12)-](/data/chemimg/27600/36965-71-6.png)
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![Phosphonothioic acid,P-ethyl-, S-[2-(diethylamino)ethyl] O-ethyl ester](http://img.cochemist.com/ccimg/21800/21738-25-0_b.png)
![3-[fluoro(methyl)phosphoryl]oxypropyl-trimethylazanium;iodide](http://img.cochemist.com/ccimg/2000/1978-17-2.png)
![3-[fluoro(methyl)phosphoryl]oxypropyl-trimethylazanium;iodide](http://img.cochemist.com/ccimg/2000/1978-17-2_b.png)
![[FLUORO(METHYL)PHOSPHORYL]OXYCYCLOHEXANE](http://img.cochemist.com/ccimg/400/329-99-7.png)
![[FLUORO(METHYL)PHOSPHORYL]OXYCYCLOHEXANE](http://img.cochemist.com/ccimg/400/329-99-7_b.png)
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![Dibenz[b,f][1,4]oxazepine](http://img.cochemist.com/ccimg/300/257-07-8_b.png)
![2-[(2E)-2-(2-CHLOROBENZYLIDENE)HYDRAZINO]-5-NITROPYRIDINE](http://img.cochemist.com/ccimg/100/77-81-6.png)
![2-[(2E)-2-(2-CHLOROBENZYLIDENE)HYDRAZINO]-5-NITROPYRIDINE](http://img.cochemist.com/ccimg/100/77-81-6_b.png)
![Phosphonothioic acid,P-methyl-, S-[2-[bis(1-methylethyl)amino]ethyl] O-ethyl ester](http://img.cochemist.com/ccimg/50800/50782-69-9.png)
![Phosphonothioic acid,P-methyl-, S-[2-[bis(1-methylethyl)amino]ethyl] O-ethyl ester](http://img.cochemist.com/ccimg/50800/50782-69-9_b.png)
