Hong-Cai Zhou

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Name: Zhou, Dr. Hongcai (Joe); 周宏才
Organization: Texas A&M University , USA
Department: Departmentof Chemistry
Title: Professor(PhD)

TOPICS

Co-reporter:Jiandong Pang, Shuai Yuan, Junsheng Qin, Caiping Liu, Christina Lollar, Mingyan Wu, Daqiang Yuan, Hong-Cai Zhou, and Maochun Hong
Journal of the American Chemical Society November 22, 2017 Volume 139(Issue 46) pp:16939-16939
Publication Date(Web):October 26, 2017
DOI:10.1021/jacs.7b09973
Ligands with flexible conformations add to the structural diversity of metal–organic frameworks but, at the same time, pose a challenge to structural design and prediction. Representative examples include Zr-tetracarboxylate-based MOFs, which afford assorted structures for a wide range of applications, but also complicate the structural control. Herein, we systematically studied the formation mechanism of a series of (4,8)-connected Zr-tetracarboxylate-based MOFs by altering the substituents on different positions of the organic linkers. Different ligand rotamers give rise to three types of structures with flu, scu, and csq topologies. A combination of experiment and molecular simulation indicate that the steric hindrance of the substituents at different positions dictates the resulting MOF structures. Additionally, the controllable formation of different structures was successfully implemented by a combination of linkers with different steric effects at specific positions.
Co-reporter:Feng-Ming Zhang, Long-Zhang Dong, Jun-Sheng Qin, Wei Guan, Jiang Liu, Shun-Li Li, Meng Lu, Ya-Qian Lan, Zhong-Min Su, and Hong-Cai Zhou
Journal of the American Chemical Society May 3, 2017 Volume 139(Issue 17) pp:6183-6183
Publication Date(Web):April 7, 2017
DOI:10.1021/jacs.7b01559
Imidazole molecules were frequently incorporated into porous materials to improve their proton conductivity. To investigate how different arrangements of imidazoles in metal–organic frameworks (MOFs) affect the overall proton conduction, we designed and prepared a MOF-based model system. It includes an Fe–MOF as the blank, an imidazole@Fe–MOF (Im@Fe–MOF) with physically adsorbed imidazole, and an imidazole–Fe–MOF (Im–Fe–MOF), which contains chemically coordinated imidazole molecules. The parent Fe–MOF, synthesized from the exchange of carboxylates in the preformed [Fe3(μ3–O)](carboxylate)6 clusters and multitopic carboxylate ligands, serves as a control. The Im@Fe–MOF was prepared by encapsulating free imidazole molecules into the pores of the Fe–MOF, whereas the Im–Fe–MOF was obtained in situ, in which imidazole ligands coordinate to the metal nodes of the framework. Proton-conductivity analyses revealed that the proton conductivity of Im–Fe–MOF was approximately two orders of magnitude greater than those of Fe–MOF and Im@Fe–MOF at room temperature. The high proton conductivity of 1.21 × 10–2 S cm–1 at 60 °C for Im–Fe–MOF ranks among the highest performing MOFs ever reported. The results of the density functional theory calculations suggest that coordinated imidazole molecules in Im–Fe–MOF provide a greater concentration of protons for proton transportation than do coordinated water molecules in Fe–MOF alone. Besides, Im–Fe–MOF exhibits steadier performance than Im@Fe–MOF does after being washed with water. Our investigation using the above ideal crystalline model system demonstrates that compared to disorderly arranged imidazole molecules in pores, the immobilized imidazole molecules by coordination bonds in the framework are more prone to form proton–conduction pathways and thus perform better and steadier in water-mediated proton conduction.
Co-reporter:Ming Xu, Shuai Yuan, Xin-Yu Chen, Yu-Jie Chang, Gregory Day, Zhi-Yuan Gu, and Hong-Cai Zhou
Journal of the American Chemical Society June 21, 2017 Volume 139(Issue 24) pp:8312-8312
Publication Date(Web):May 24, 2017
DOI:10.1021/jacs.7b03450
Two-dimensional metal–organic framework (MOF) nanosheets are utilized as effective enzyme inhibitors, providing an inspiring means to enhance the control of cellular processes as well as improve our understanding of the surface chemistry between MOFs and enzymes. In this paper, we demonstrated that the activity of α-chymotrypsin (ChT) can be effectively inhibited with 96.9% inhibition by 2-D Cu(bpy)2(OTf)2 nanosheets, while Zn2(bim)4 nanosheets show no significant inhibition effect toward ChT. Kinetic studies revealed that the material acts as a competitive inhibitor toward ChT. Furthermore, fluorescence and circular dichroism spectroscopy reveal that the 2-D MOF nanosheets do not change the secondary structure of the enzyme. The Cu(II) center of the 2-D nanosheets binds the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) molecules in the buffer, leading to an electrostatic interaction between the nanosheets and the enzyme. In addition, the irreversible coordination interactions between Cu(II) center and His-57 played an important role during the inhibition process, as supported by ionic strength experiments and UV absorbance changes of Cu(II) d–d transitions. As a result, the substrate is prevented from reaching the active sites of the enzyme causing enzyme inhibition. The modulation of enzyme activity by 2-D MOF nanosheets opens up a new direction for the exploration of the MOF–bio interface in physiological and catalytic systems.
Co-reporter:Yanjun Ding, Ying-Pin Chen, Xinlei Zhang, Liang Chen, Zhaohui Dong, Hai-Long Jiang, Hangxun Xu, and Hong-Cai Zhou
Journal of the American Chemical Society July 12, 2017 Volume 139(Issue 27) pp:9136-9136
Publication Date(Web):June 27, 2017
DOI:10.1021/jacs.7b04829
Creating ordered two-dimensional (2D) metal–organic framework (MOF) nanosheets has attracted extensive interest. However, it still remains a great challenge to synthesize ultrathin 2D MOF nanosheets with controlled thickness in high yields. In this work, we demonstrate a novel intercalation and chemical exfoliation approach to obtain MOF nanosheets from intrinsically layered MOF crystals. This approach involves two steps: first, layered porphyrinic MOF crystals are intercalated with 4,4′-dipyridyl disulfide through coordination bonding with the metal nodes; subsequently, selective cleavage of the disulfide bond induces exfoliation of the intercalated MOF crystals, leading to individual freestanding MOF nanosheets. This chemical exfoliation process can proceed efficiently at room temperature to produce ultrathin (∼1 nm) 2D MOF nanosheets in ∼57% overall yield. The obtained ultrathin nanosheets exhibit efficient and far superior heterogeneous photocatalysis performance compared with the corresponding bulk MOF.
Co-reporter:Lanfang Zou;Xinyu Yang;Shuai Yuan
CrystEngComm (1999-Present) 2017 vol. 19(Issue 33) pp:4868-4871
Publication Date(Web):2017/08/21
DOI:10.1039/C7CE00593H
The design and synthesis of flexible monomer-based covalent organic frameworks (COFs) have been considered a challenge. Herein, we describe the design and synthesis of a new flexible monomer-based COF, termed PPN-30 (PPN meaning porous polymer network), by the use of a flexible alkyl amine, 1,4-cyclohexanediamine, combined with 1,3,5-triformylbenzene. The structure and gas adsorption properties of PPN-30 were carefully investigated.
Co-reporter:Xizhen Lian;Yu Fang;Elizabeth Joseph;Qi Wang;Jialuo Li;Sayan Banerjee;Christina Lollar;Xuan Wang
Chemical Society Reviews 2017 vol. 46(Issue 11) pp:3386-3401
Publication Date(Web):2017/06/06
DOI:10.1039/C7CS00058H
The ex vivo application of enzymes in various processes, especially via enzyme immobilization techniques, has been extensively studied in recent years in order to enhance the recyclability of enzymes, to minimize enzyme contamination in the product, and to explore novel horizons for enzymes in biomedical applications. Possessing remarkable amenability in structural design of the frameworks as well as almost unparalelled surface tunability, Metal–Organic Frameworks (MOFs) have been gaining popularity as candidates for enzyme immobilization platforms. Many MOF–enzyme composites have achieved unprecedented results, far outperforming free enzymes in many aspects. This review summarizes recent developments of MOF–enzyme composites with special emphasis on preparative techniques and the synergistic effects of enzymes and MOFs. The applications of MOF–enzyme composites, primarily in transferation, catalysis and sensing, are presented as well. The enhancement of enzymatic activity of the composites over free enzymes in biologically incompatible conditions is emphasized in many cases.
Co-reporter:Larissa Stewart;Weigang Lu;Zhang-Wen Wei;Daryush Ila;Carla Padilla
Dalton Transactions 2017 vol. 46(Issue 41) pp:14270-14276
Publication Date(Web):2017/10/24
DOI:10.1039/C7DT03394J
A zirconium metal–organic framework (MOF), PCN-111, has been synthesized by using an elongated ditopic carboxylate linker, 4,4′-(buta-1,3-diyne-1,4-diyl)dibenzoate. Single crystal X-ray diffraction characterization indicates that the noninterpenetrated microporous structure of PCN-111 is isoreticular to UIO MOFs with 12 connected Zr6O4(OH)4(CO2)12 clusters and a fcu topology. It was successfully activated through a solvent exchange with acetone followed by controlled evacuation and its gas sorption was reported. By using 77 K nitrogen adsorption isotherm and strictly applying three consistency criteria, the BET surface area for PCN-111 was calculated to be 4825 m2 g−1. Pore size distribution analysis suggests that the sizes of cavities contributing to nitrogen adsorption are predominately in the range of 15 to 20 Å, which are in good agreement with the two polyhedral cages (15.6 and 20.2 Å, respectively) in the single crystal X-ray solved structure. Owing to its relatively high crystal density (0.42 g cm−3), the volumetric surface area for PCN-111 was calculated to be 2026 m2 cm−3. The value is among the highest of all the reported ultrahigh surface area MOF materials. The exceptionally high microporosity of PCN-111 has also been validated by comparison with the simulated nitrogen adsorption isotherm derived from multipurpose simulation code MUSIC.
Co-reporter:Dr. Jiong Pang;Shuai Yuan;Dr. Dongying Du;Christina Lollar;Dr. Liangliang Zhang;Dr. Mingyan Wu;Dr. Daqiang Yuan; Dr. Hong-Cai Zhou; Dr. Maochun Hong
Angewandte Chemie International Edition 2017 Volume 56(Issue 46) pp:14622-14626
Publication Date(Web):2017/11/13
DOI:10.1002/anie.201709186
AbstractA series of flexible MOFs (PCN-605, PCN-606, and PCN-700) are synthesized and applied to reversible bromine encapsulation and release. The chemical stability of these Zr-MOFs ensures the framework's integrity during the bromine adsorption, while the framework's flexibility allows for structural adaptation upon bromine uptake to afford stronger host–guest interactions and therefore higher bromine adsorption capacities. The flexible MOFs act as bromine-nanocontainers which elongate the storage time of volatile halides under ambient conditions. Furthermore, the bromine pre-adsorbed flexible MOFs can be used as generic bromine sources for bromination reactions giving improved yields and selectivities under ambient conditions when compared with liquid bromine.
Co-reporter:Lanfang Zou;Yujia Sun;Sai Che;Xinyu Yang;Xuan Wang;Mathieu Bosch;Qi Wang;Hao Li;Mallory Smith;Shuai Yuan;Zachary Perry
Advanced Materials 2017 Volume 29(Issue 37) pp:
Publication Date(Web):2017/10/01
DOI:10.1002/adma.201700229
One of the most pressing environmental concerns of our age is the escalating level of atmospheric CO2. Intensive efforts have been made to investigate advanced porous materials, especially porous organic polymers (POPs), as one type of the most promising candidates for carbon capture due to their extremely high porosity, structural diversity, and physicochemical stability. This review provides a critical and in-depth analysis of recent POP research as it pertains to carbon capture. The definitions and terminologies commonly used to evaluate the performance of POPs for carbon capture, including CO2 capacity, enthalpy, selectivity, and regeneration strategies, are summarized. A detailed correlation study between the structural and chemical features of POPs and their adsorption capacities is discussed, mainly focusing on the physical interactions and chemical reactions. Finally, a concise outlook for utilizing POPs for carbon capture is discussed, noting areas in which further work is needed to develop the next-generation POPs for practical applications.
Co-reporter:Xinyu Yang, Lanfang Zou, Hong-Cai Zhou
Polymer 2017 Volume 126(Volume 126) pp:
Publication Date(Web):22 September 2017
DOI:10.1016/j.polymer.2017.07.028
•A novel strategy was designed to construct alkylamine tethered PPNs, which demonstrated high CO2 uptake.•Among them, the CO2 uptake of PPN-200-TAEA reaches 42 cm3/g (8.3 wt%) and its calculated CO2/N2 selectivity reaches 289.•Given the outstanding stability and high CO2 adsorption, the PPN-200-TAEA has great potential in post-combustion carbon capture.Porous polymer networks (PPNs) is an emerging category of advanced porous materials that are of interest for carbon capture due to their high physicochemical stability and convenient functionalization process. Herein, a series of alkylamine tethered PPN-200 (PPN-200-DETA, PPN-200-TETA and PPN-200-TAEA) were prepared through a novel post-synthetic strategy. Due to the presence of alkylamine groups, PPN-200-TAEA has CO2 uptakes of 42 cm3/g (at 298 K and 0.15 bar) and 55 cm3/g (at 298 K and 1 bar), and a calculated CO2/N2 selectivity of 289, which demonstrate its potential in postcombustion carbon capture application.Download high-res image (161KB)Download full-size image
Co-reporter:Jun-Sheng Qin;Shuai Yuan;Qi Wang;Ali Alsalme
Journal of Materials Chemistry A 2017 vol. 5(Issue 9) pp:4280-4291
Publication Date(Web):2017/02/28
DOI:10.1039/C6TA10281F
Owing to their permanent porosity, tunability and multifunctionalization, metal–organic framework (MOF) materials have captured widespread interest in various fields, including gas storage and separation, catalysis, and energy storage. However, precise control over the composition, structure and properties of MOF materials remains a generally elusive but worthwhile dream. The stepwise assembly of porous crystalline MOF materials provides possibility to access this goal. In this review, we focus on four kinds of mixed-linker MOFs, (i) pillared-layer mixed-linker MOFs, (ii) cage-directed mixed-linker MOFs, (iii) cluster-based mixed-linker MOFs, and (iv) structure templated mixed-linker MOFs. The achieved progress and existing problems are discussed, and the opportunities and challenges of mixed-linker MOFs and their related applications are anticipated.
Co-reporter:Xiu-Liang Lv, Kecheng Wang, Bin Wang, Jie Su, Xiaodong Zou, Yabo Xie, Jian-Rong LiHong-Cai Zhou
Journal of the American Chemical Society 2016 Volume 139(Issue 1) pp:211-217
Publication Date(Web):December 11, 2016
DOI:10.1021/jacs.6b09463
A base-resistant porphyrin metal–organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni8(OH)4(H2O)2Pz12] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F–, CO32–, and PO43– ions. Interestingly, the Mn3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C–H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOF was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.
Co-reporter:Jun-Sheng Qin; Dong-Ying Du; Mian Li; Xi-Zhen Lian; Long-Zhang Dong; Mathieu Bosch; Zhong-Min Su; Qiang Zhang; Shun-Li Li; Ya-Qian Lan; Shuai Yuan
Journal of the American Chemical Society 2016 Volume 138(Issue 16) pp:5299-5307
Publication Date(Web):April 5, 2016
DOI:10.1021/jacs.6b01093
Quests for advanced functionalities in metal–organic frameworks (MOFs) inevitably encounter increasing complexity in their tailored framework architectures, accompanied by heightened challenges with their geometric design. In this paper, we demonstrate the feasibility of rationally exploiting topological prediction as a blueprint for predesigned MOFs. A new triangular frusta secondary building unit (SBU), {Zn4(tz)3}, was bridged by three TDC2– fragments to initially form a trigonal prismatic node, {Zn8(tz)6(TDC)3} (Htz = 1H-1,2,3-triazole and H2TDC = 2,5-thiophenedicarboxylic acid). Furthermore, the trigonal prism unit can be considered as a double SBU derived from triply bound triangular frusta. By considering theoretical derived nets for linking this trigonal-prismatic node with ditopic, tritopic, and tetratopic linkers, we have synthesized and characterized a new family of MOFs that adopt the decorated lon, jea, and xai nets, respectively. Pore sizes have also been successively increased within TPMOF-n family, which facilitates heterogeneous biomimetic catalysis with Fe–porphyrin-based TPMOF-7 as a catalyst.
Co-reporter:Shuai Yuan; Ying-Pin Chen; Jun-Sheng Qin; Weigang Lu; Lanfang Zou; Qiang Zhang; Xuan Wang; Xing Sun
Journal of the American Chemical Society 2016 Volume 138(Issue 28) pp:8912-8919
Publication Date(Web):June 25, 2016
DOI:10.1021/jacs.6b04501
Precise placement of multiple functional groups in a highly ordered metal–organic framework (MOF) platform allows the tailoring of the pore environment, which is required for advanced applications. To realize this, we present a comprehensive study on the linker installation method, in which a stable MOF with coordinatively unsaturated Zr6 clusters was employed and linkers bearing different functional groups were postsynthetically installed. A Zr-MOF with inherent missing linker sites, namely, PCN-700, was initially constructed under kinetic control. Twelve linkers with different substituents were then designed to study their effect on MOF formation kinetics and therefore resulting MOF structures. Guided by the geometrical analysis, linkers with different lengths were installed into a parent PCN-700, giving rise to 11 new MOFs and each bearing up to three different functional groups in predefined positions. Systematic variation of the pore volume and decoration of pore environment were realized by linker installation, which resulted in synergistic effects including an enhancement of H2 adsorption capacities of up to 57%. In addition, a size-selective catalytic system for aerobic alcohol oxidation reaction is built in PCN-700 through linker installation, which shows high activity and tunable size selectivity. Altogether, these results exemplify the capability of the linker installation method in the pore environment engineering of stable MOFs with multiple functional groups, giving an unparalleled level of control.
Co-reporter:Shuai Yuan; Jun-Sheng Qin; Lanfang Zou; Ying-Pin Chen; Xuan Wang; Qiang Zhang
Journal of the American Chemical Society 2016 Volume 138(Issue 20) pp:6636-6642
Publication Date(Web):May 6, 2016
DOI:10.1021/jacs.6b03263
Guided by thermodynamics, we have synthesized two mixed-linker zirconium-based metal–organic frameworks (Zr-MOFs), namely, PCN-133 and PCN-134. Both of them possess a layer-pillar structure, in which the connection between Zr6 clusters and primary BTB linkers form a (3,6)-connected kdg layer that is further extended into 3D frameworks by auxiliary DCDPS/TCPP linkers (BTB = benzene tribenzoate, DCDPS = 4,4′-dicarboxydiphenyl sulfone, TCPP = tetrakis(4-carboxyphenyl)porphyrin). PCN-134 demonstrates high porosity (N2 uptake of 717 cm3·g–1 and BET surface area of 1946 cm2·g–1) and excellent chemical stability in aqueous solutions with pH values ranging from 0 to 13. More importantly, PCN-134 tolerates the partial absence of auxiliary linkers leading to structural defects during the assembly process while preserving its framework integrity. Furthermore, the defect density can be systematically controlled by tuning the occupancy of the auxiliary linker, which in turn affects the MOF properties. For instance, the dichromate uptake of PCN-134 is tuned by adjusting the BTB/TCPP ratios, which gives rise to an efficient dichromate absorbent when the TCPP molar ratio in linkers is set as 22%. In addition, the photocatalytic reduction of Cr(VI) in aqueous solution was also performed by PCN-134–22%TCPP which exhibits excellent catalytic activity. This work not only opens up a new synthetic route toward mixed-linker MOFs, but also provides tunable control of MOF defects and, in turn, the properties.
Co-reporter:Hai-Qun Xu; Kecheng Wang; Meili Ding; Dawei Feng; Hai-Long Jiang
Journal of the American Chemical Society 2016 Volume 138(Issue 16) pp:5316-5320
Publication Date(Web):March 25, 2016
DOI:10.1021/jacs.6b01414
The synthesis of phase-pure metal–organic frameworks (MOFs) is of prime importance but remains a significant challenge because of the flexible and diversified coordination modes between metal ions and organic linkers. In this work, we report the synthesis of phase-pure MOFs via a facile seed-mediated approach. For several “accompanying” pairs of Zr–porphyrinic MOFs that are prone to yield mixtures, by fixing all reaction parameters except introducing seed crystals, MOFs in phase-pure forms have been obtained because the stage of MOF nucleation, which generates mixed nuclei, is bypassed. In addition, phase-pure MOF isomers with distinct pore structures have also been prepared through such an approach, revealing its versatility. To the best of our knowledge, this is an initial report on seed-assisted synthesis of phase-pure MOFs.
Co-reporter:Lanfang Zou, Dawei Feng, Tian-Fu Liu, Ying-Pin Chen, Shuai Yuan, Kecheng Wang, Xuan Wang, Stephen Fordham and Hong-Cai Zhou  
Chemical Science 2016 vol. 7(Issue 2) pp:1063-1069
Publication Date(Web):02 Nov 2015
DOI:10.1039/C5SC03620H
Exploitation of new titanium metal–organic frameworks (Ti-MOFs) with high crystallinity has been attracting great attention due to their vast application potential in photocatalysis. Herein a versatile synthetic strategy, namely, High Valence Metathesis and Oxidation (HVMO), is developed to synthesize a series of Ti-MOFs with predesigned topologies and structures. The crystallinity of these Ti-MOFs was well maintained throughout, as confirmed by powder X-ray diffraction and gas adsorption measurements. Significantly, there were only a few examples of Ti-MOFs, not to mention a general synthetic strategy for various kinds of Ti-MOFs in the literature. This contribution also illustrates the intriguing potential of Ti-MOF platforms in photocatalysis.
Co-reporter:Xuan Wang, Weigang Lu, Zhi-Yuan Gu, Zhangwen Wei and Hong-Cai Zhou  
Chemical Communications 2016 vol. 52(Issue 9) pp:1926-1929
Publication Date(Web):01 Dec 2015
DOI:10.1039/C5CC08614K
An anionic metal–organic framework, PCN-99, has been synthesized through a topology-guided strategy; its underlying bor-net is realized by the use of a tetrahedral [In(COO)4]− node and a judiciously designed trigonal planar linker. In light of its anionic nature, the inherent cuboctahedral cage and 1D channel make PCN-99 an excellent matrix to encapsulate the photocatalytic [Ru(bpy)3]2+.
Co-reporter:Dahuan Liu;Xuan Wang;Ying-Pin Chen;Shuai Yuan;Chongli Zhong
Science China Chemistry 2016 Volume 59( Issue 8) pp:975-979
Publication Date(Web):2016 August
DOI:10.1007/s11426-016-0060-3
With the aid of a postsynthetic metathesis method, an inert nitrogen-rich porphyrinic metal-organic framework can exhibit a high catalytic activity in one-pot deacetalization-Knoevenagel condensation reaction.
Co-reporter:Wolfgang M. Verdegaal;Kecheng Wang;Dr. Julian P. Sculley;Dr. Mario Wriedt;Dr. Hong-Cai Zhou
ChemSusChem 2016 Volume 9( Issue 6) pp:636-643
Publication Date(Web):
DOI:10.1002/cssc.201501464

Abstract

This manuscript presents experimental data for 20 adsorption materials (metal–organic frameworks, porous polymer networks, and Zeolite-5A), including CO2 and N2 isotherms and heat capacities. With input from only experimental data, working capacities per energy for each material were calculated. Furthermore, by running seven different carbon-capture scenarios in which the initial flue-gas composition and process temperature was systematically changed, we present a range of performances for each material and quantify how sensitive each is to these varying parameters. The presented calculations provide researchers with a tool to investigate promising carbon-capture materials more easily and completely.

Co-reporter:Jihye Park;Dr. Qin Jiang;Dr. Dawei Feng;Dr. Hong-Cai Zhou
Angewandte Chemie 2016 Volume 128( Issue 25) pp:7304-7309
Publication Date(Web):
DOI:10.1002/ange.201602417

Abstract

Development of a photosensitizing system that can reversibly control the generation of singlet oxygen (1O2) is of great interest for photodynamic therapy (PDT). Recently several photosensitizer–photochromic-switch dyads were reported as a potential means of the 1O2 control in PDT. However, the delivery of such a homogeneous molecular dyad as designed (e.g., optimal molar ratio) is extremely challenging in living systems. Herein we show a Zr-MOF nanoplatform, demonstrating energy transfer-based 1O2 controlled PDT. Our strategy allows for tuning the ratios between photosensitizer and the switch molecule, enabling maximum control of 1O2 generation. Meanwhile, the MOF provides proximal placement of the functional entities for efficient intermolecular energy transfer. As a result, the MOF nanoparticle formulation showed enhanced PDT efficacy with superior 1O2 control compared to that of homogeneous molecular analogues.

Co-reporter:Jihye Park;Dr. Qin Jiang;Dr. Dawei Feng;Dr. Hong-Cai Zhou
Angewandte Chemie 2016 Volume 128( Issue 25) pp:
Publication Date(Web):
DOI:10.1002/ange.201604085
Co-reporter:Lin-Bing Sun, Xiao-Qin Liu and Hong-Cai Zhou  
Chemical Society Reviews 2015 vol. 44(Issue 15) pp:5092-5147
Publication Date(Web):05 Jun 2015
DOI:10.1039/C5CS00090D
Mesoporous solid bases are extremely desirable in green catalytic processes, due to their advantages of accelerated mass transport, negligible corrosion, and easy separation. Great progress has been made in mesoporous solid bases in the last decade. In addition to their wide applications in the catalytic synthesis of organics and fine chemicals, mesoporous solid bases have also been used in the field of energy and environmental catalysis. Development of mesoporous solid bases is therefore of significant importance from both academic and practical points of view. In this review, we provide an overview of the recent advances in mesoporous solid bases, which is basically grouped by the support type and each category is illustrated with typical examples. Cooperative catalysts derived from the incorporation of additional functionalities (i.e. acid and metal) into mesoporous solid bases are also included. The fundamental principles of how to design and fabricate basic materials with mesostructure are highlighted. The mechanism of the formation of basic sites in different mesoporous systems is discussed as well.
Co-reporter:Shuai Yuan; Weigang Lu; Ying-Pin Chen; Qiang Zhang; Tian-Fu Liu; Dawei Feng; Xuan Wang; Junsheng Qin
Journal of the American Chemical Society 2015 Volume 137(Issue 9) pp:3177-3180
Publication Date(Web):February 25, 2015
DOI:10.1021/ja512762r
A unique strategy, sequential linker installation (SLI), has been developed to construct multivariate MOFs with functional groups precisely positioned. PCN-700, a Zr-MOF with eight-connected Zr6O4(OH)8(H2O)4 clusters, has been judiciously designed; the Zr6 clusters in this MOF are arranged in such a fashion that, by replacement of terminal OH–/H2O ligands, subsequent insertion of linear dicarboxylate linkers is achieved. We demonstrate that linkers with distinct lengths and functionalities can be sequentially installed into PCN-700. Single-crystal to single-crystal transformation is realized so that the positions of the subsequently installed linkers are pinpointed via single-crystal X-ray diffraction analyses. This methodology provides a powerful tool to construct multivariate MOFs with precisely positioned functionalities in the desired proximity, which would otherwise be difficult to achieve.
Co-reporter:Ying-Pin Chen; Yangyang Liu; Dahuan Liu; Mathieu Bosch
Journal of the American Chemical Society 2015 Volume 137(Issue 8) pp:2919-2930
Publication Date(Web):February 12, 2015
DOI:10.1021/ja5103579
Knowledge about the interactions between gas molecules and adsorption sites is essential to customize metal-organic frameworks (MOFs) as adsorbents. The dynamic interactions occurring during adsorption/desorption working cycles with several states are especially complicated. Even so, the gas dynamics based upon experimental observations and the distribution of guest molecules under various conditions in MOFs have not been extensively studied yet. In this work, a direct time-resolved diffraction structure envelope (TRDSE) method using sequential measurements by in situ synchrotron powder X-ray diffraction has been developed to monitor several gas dynamic processes taking place in MOFs: infusion, desorption, and gas redistribution upon temperature change. The electron density maps indicate that gas molecules prefer to redistribute over heterogeneous types of sites rather than to exclusively occupy the primary binding sites. We found that the gas molecules are entropically driven from open metal sites to larger neighboring spaces during the gas infusion period, matching the localized-to-mobile mechanism. In addition, the partitioning ratio of molecules adsorbed at each site varies with different temperatures, as opposed to an invariant distribution mode. Equally important, the gas adsorption in MOFs is intensely influenced by the gas–gas interactions, which might induce more molecules to be accommodated in an orderly compact arrangement. This sequential TRDSE method is generally applicable to most crystalline adsorbents, yielding information on distribution ratios of adsorbates at each type of site.
Co-reporter:Qiang Zhang; Jie Su; Dawei Feng; Zhangwen Wei; Xiaodong Zou
Journal of the American Chemical Society 2015 Volume 137(Issue 32) pp:10064-10067
Publication Date(Web):July 27, 2015
DOI:10.1021/jacs.5b04695
We have successfully constructed a metal–organic framework, denoted as PCN-128W, starting from chromophoric linker and zirconium salt. PCN-128W exhibits interesting piezofluorochromic behavior, the color reversibly changes from white to yellow and so does the emission maximum from 470 to 538 nm. The stepwise fluorescence change was monitored by fluorospectroscopy which demonstrated gradual shift of the emission maximum when sequential compression was exerted. In order to gain deep insights into the piezofluorochromic mechanism, both the white and yellow phases are structurally characterized.
Co-reporter:Kecheng Wang; Xiu-Liang Lv; Dawei Feng; Jian Li; Shuangming Chen; Junliang Sun; Li Song; Yabo Xie; Jian-Rong Li
Journal of the American Chemical Society 2015 Volume 138(Issue 3) pp:914-919
Publication Date(Web):December 30, 2015
DOI:10.1021/jacs.5b10881
Guided by a top-down topological analysis, a metal–organic framework (MOF) constructed by pyrazolate-based porphyrinic ligand, namely, PCN-601, has been rationally designed and synthesized, and it exhibits excellent stability in alkali solutions. It is, to the best of our knowledge, the first identified MOF that can retain its crystallinity and porosity in saturated sodium hydroxide solution (∼20 mol/L) at room temperature and 100 °C. This almost pushes base-resistance of porphyrinic MOFs (even if MOFs) to the limit in aqueous media and greatly extends the range of their potential applications. In this work, we also tried to interpret the stability of PCN-601 from both thermodynamic and kinetic perspectives.
Co-reporter:Dahuan Liu; Tian-Fu Liu; Ying-Pin Chen; Lanfang Zou; Dawei Feng; Kecheng Wang; Qiang Zhang; Shuai Yuan; Chongli Zhong
Journal of the American Chemical Society 2015 Volume 137(Issue 24) pp:7740-7746
Publication Date(Web):May 26, 2015
DOI:10.1021/jacs.5b02999
A quenching-triggered reversible single-crystal-to-single-crystal (SC-SC) phase transition was discovered in a metal–organic framework (MOF) PCN-526. During the phase transition, the one-dimensional channel of PCN-526 distorts from square to rectangular in shape while maintaining single crystallinity. Although SC-SC transformations have been frequently observed in MOFs, most reports have focused on describing the resulting structural alterations without shedding light on the mechanism for the transformation. Interestingly, modifying the occupancy or species of metal ions in the extra-framework sites, which provides mechanistic insight into the causes for the transformation, can forbid this phase transition. Moreover, as a host scaffold, PCN-526 presents a platform for modulation of the photoluminescence properties by encapsulation of luminescent guest molecules. Through judicious choice of these guest molecules, responsive luminescence caused by SC-SC transformations can be detected, introducing a new strategy for the design of novel luminescent MOF materials.
Co-reporter:Jun-Sheng Qin; Dong-Ying Du; Wei Guan; Xiang-Jie Bo; Ya-Fei Li; Li-Ping Guo; Zhong-Min Su; Yuan-Yuan Wang; Ya-Qian Lan
Journal of the American Chemical Society 2015 Volume 137(Issue 22) pp:7169-7177
Publication Date(Web):May 1, 2015
DOI:10.1021/jacs.5b02688
Two novel polyoxometalate (POM)-based metal–organic frameworks (MOFs), [TBA]3[ε-PMoV8MoVI4O36(OH)4Zn4][BTB]4/3·xGuest (NENU-500, BTB = benzene tribenzoate, TBA+ = tetrabutylammonium ion) and [TBA]3[ε-PMoV8MoVI4O37(OH)3Zn4][BPT] (NENU-501, BPT = [1,1′-biphenyl]-3,4′,5-tricarboxylate), were isolated. In these compounds, the POM fragments serving as nodes were directly connected with organic ligands giving rise to three-dimensional (3D) open frameworks. The two anionic frameworks were balanced by TBA+ ions residing inside the open channels. They exhibit not only good stability in air but also tolerance to acidic and basic media. Furthermore, they were employed as electrocatalysts for the hydrogen evolution reaction (HER) owing to the combination of the redox activity of a POM unit and the porosity of a MOF. Meanwhile, the HER activities of ε(trim)4/3, NENU-5, and HKUST-1 were also studied for comparison. Remarkably, as a 3D hydrogen-evolving cathode operating in acidic electrolytes, NENU-500 exhibits the highest activity among all MOF materials. It shows an onset overpotential of 180 mV and a Tafel slope of 96 mV·dec–1, and the catalytic current density can approach 10 mA·cm–2 at an overpotential of 237 mV. Moreover, NENU-500 and NENU-501 maintain their electrocatalytic activities after 2000 cycles.
Co-reporter:Shuai Yuan, Tian-Fu Liu, Dawei Feng, Jian Tian, Kecheng Wang, Junsheng Qin, Qiang Zhang, Ying-Pin Chen, Mathieu Bosch, Lanfang Zou, Simon J. Teat, Scott J. Dalgarno and Hong-Cai Zhou  
Chemical Science 2015 vol. 6(Issue 7) pp:3926-3930
Publication Date(Web):28 Apr 2015
DOI:10.1039/C5SC00916B
We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal–organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.
Co-reporter:Xizhen Lian, Dawei Feng, Ying-Pin Chen, Tian-Fu Liu, Xuan Wang and Hong-Cai Zhou  
Chemical Science 2015 vol. 6(Issue 12) pp:7044-7048
Publication Date(Web):02 Sep 2015
DOI:10.1039/C5SC02587G
Kinetic labilization of the Fe(III)–O coordination bond in a mesoporous metal–organic framework, PCN-333-Fe(III), is realized by the reduction of Fe(III) by Cr(II). The Fe(II)–Cr(II) metathesis is thus completely achieved followed by this reductive labilization process that generates PCN-333-Cr(III). The kinetic inertness of Cr(III) provides PCN-333-Cr(III) with enhanced chemical stability as well as a broader range of applications compared to those of PCN-333-Fe(III). For instance, alkylamine incorporated PCN-333-Cr(III) demonstrated significant carbon dioxide uptake while PCN-333-Fe(III) lost its crystallinity after alkylamine treatment.
Co-reporter:Lin-Bing Sun, Ai-Guo Li, Xiao-Dan Liu, Xiao-Qin Liu, Dawei Feng, Weigang Lu, Daqiang Yuan and Hong-Cai Zhou  
Journal of Materials Chemistry A 2015 vol. 3(Issue 7) pp:3252-3256
Publication Date(Web):07 Jan 2015
DOI:10.1039/C4TA06039C
Due to their synthetic diversification, low skeletal density, and high physicochemical stability, porous polymer networks (PPNs) are highly promising in a variety of applications such as carbon capture. Nevertheless, complicated monomers and/or expensive catalysts are normally utilized for their synthesis, which makes the process tedious, costly, and hard to scale up. In this study, a facile nucleophilic substitution reaction was designed to fabricate PPNs from low-cost monomers, namely chloromethyl benzene and ethylene diamine. A surfactant template was also used to direct the assembly, leading to the formation of PPN with enhanced porosity. It is fascinating that the polymerization reactions can occur at the low temperature of 63 °C in the absence of any catalyst. The obtained PPNs contain abundant secondary amines, which offer appropriate adsorbate–adsorbent interactions from the viewpoints of selective CO2 capture and energy-efficient regeneration of the adsorbents. Hence, these PPNs are highly active in selective adsorption of CO2, and unusually high CO2/N2 and CO2/CH4 selectivity was obtained. Moreover, the PPN adsorbents can be completely regenerated under mild conditions.
Co-reporter:Mark D. Young, Qiang Zhang, Hong-Cai Zhou
Inorganica Chimica Acta 2015 Volume 424() pp:216-220
Publication Date(Web):1 January 2015
DOI:10.1016/j.ica.2014.09.010
•Four MOPs were constructed based on dinuclear Ru paddlewheels.•Ligand-Angle-Driven Assembly was applied to obtain MOPs with different structure.•Ru2n+ paddlewheels show redox activity even after coordinated into MOPs.•The structure of MOPs were barely affected by the oxidation states of Ru2n+ centers.•Both electrochemistry and magnetic properties show moderate communications between the Ru25+ paddlewheels.Reactions of Ru2n+ [n = 4 for Ru2(OAc)4 and n = 5 for Ru2(OAc)4Cl] with H2CDC (9H-3,6-carbazoledicarboxylic acid), H2BBDC (5-tert-butyl-1,3-benzenedicarboxylic acid) and H2BDC (1,3-benzenedicarboxylic acid) were conducted in inert atmospheres under solvothermal conditions in a sealed tube. Two octahedral cages, [Ru2(CDC)2Cl]6, 1 and [Ru2(CDC)2]6, 2 were obtained when starting from Ru2n+ with CDC, and two cuboctahedral cages, [Ru2(BBDC)2Cl]12, 3 and [Ru2(BDC)2]12, 4 were yielded when starting from Ru2n+ with BDC based linkers. Structures of these MOPs were characterized by single crystal X-ray analyses. The resulted MOPs have shown redox activity and magnetic properties similar to their parent metal complexes.Graphical abstractFour metal-organic polyhedra based on Ru2n+ cores and ditopic ligands have been prepared via Ligand-Angle-Driven Assembly and were structurally characterized. Octahedral and cuboctahedral cages were yielded by starting from linkers with different angles. Cyclic voltammetry measurements have revealed that reversible oxidation and reduction between Ru24+ and Ru25+ oxidation states are possible under mild conditions. Weak electron communication has been found between Ru2 nodes in compound 4. The different oxidation states show only minor changes in structure, suggesting that these polyhedra could be incorporated into a larger framework that would allow redox reactions to take place at a Ru atom site without distorting the overall structure.
Co-reporter:Jihye Park;Dawei Feng;Shuai Yuan ;Dr. Hong-Cai Zhou
Angewandte Chemie 2015 Volume 127( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/ange.201580261
Co-reporter:Jihye Park;Dawei Feng;Shuai Yuan ;Dr. Hong-Cai Zhou
Angewandte Chemie 2015 Volume 127( Issue 2) pp:440-445
Publication Date(Web):
DOI:10.1002/ange.201408862

Abstract

The controlled generation of singlet oxygen is of great interest owing to its potential applications including industrial wastewater treatment, photochemistry, and photodynamic therapy. Two photochromic metal–organic frameworks, PC-PCN and SO-PCN, have been developed. A photochromic reaction has been successfully realized in PC-PCN while maintaining its single crystallinity. In particular, as a solid-state material which inherently integrates the photochromic switch and photosensitizer, SO-PCN has demonstrated reversible control of 1O2 generation. Additionally, SO-PCN shows catalytic activity towards photooxidation of 1,5-dihydroxynaphthalene.

Co-reporter:Ying-Pin Chen;Tian-Fu Liu;Stephen Fordham
Acta Crystallographica Section B 2015 Volume 71( Issue 6) pp:613-618
Publication Date(Web):
DOI:10.1107/S205252061501584X

Two metal–organic frameworks [PCN-426(Ni) and PCN-427(Cu)] have been designed and synthesized to investigate the structure predictability using a SBB (supermolecular building blocks) approach. Tetratopic ligands featuring 120° angular carboxylate moieties were coordinated with a [Ni33-O)] cluster and a [Cu2O2] unit, respectively. As topologically predicted, 4-connected networks with square coordination adopted the nbo net for the Ni-MOF and ssb net for the Cu-MOF. PCN-426(Ni) was augmented with 12-connected octahedral SBBs, while PCN-427(Cu) was constructed with tetragonal open channels. After a CO2 supercritical drying procedure, the PCN-426(Ni) possessed a Brunauer–Emmett–Teller (BET) surface area as high as 3935 m2 g−1 and impressively high N2 uptake of 1500 cm3 g−1. This work demonstrates the generalization of the SBB strategy, finding an alternative to inconvenient synthetic processes to achieve the desired structural features.

Co-reporter:Dawei Feng;Kecheng Wang;Dr. Jie Su;Dr. Tian-Fu Liu;Jihye Park;Dr. Zhangwen Wei;Mathieu Bosch;Dr. Andrey Yakovenko;Dr. Xiaodong Zou;Dr. Hong-Cai Zhou
Angewandte Chemie 2015 Volume 127( Issue 1) pp:151-156
Publication Date(Web):
DOI:10.1002/ange.201409334

Abstract

Through topological rationalization, a zeotype mesoporous Zr-containing metal–organic framework (MOF), namely PCN-777, has been designed and synthesized. PCN-777 exhibits the largest cage size of 3.8 nm and the highest pore volume of 2.8 cm3 g−1 among reported Zr-MOFs. Moreover, PCN-777 shows excellent stability in aqueous environments, which makes it an ideal candidate as a support to incorporate different functional moieties. Through facile internal surface modification, the interaction between PCN-777 and different guests can be varied to realize efficient immobilization.

Co-reporter:Dawei Feng;Kecheng Wang;Dr. Jie Su;Dr. Tian-Fu Liu;Jihye Park;Dr. Zhangwen Wei;Mathieu Bosch;Dr. Andrey Yakovenko;Dr. Xiaodong Zou;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2015 Volume 54( Issue 1) pp:149-154
Publication Date(Web):
DOI:10.1002/anie.201409334

Abstract

Through topological rationalization, a zeotype mesoporous Zr-containing metal–organic framework (MOF), namely PCN-777, has been designed and synthesized. PCN-777 exhibits the largest cage size of 3.8 nm and the highest pore volume of 2.8 cm3 g−1 among reported Zr-MOFs. Moreover, PCN-777 shows excellent stability in aqueous environments, which makes it an ideal candidate as a support to incorporate different functional moieties. Through facile internal surface modification, the interaction between PCN-777 and different guests can be varied to realize efficient immobilization.

Co-reporter:Jihye Park;Dawei Feng;Shuai Yuan ;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2015 Volume 54( Issue 2) pp:430-435
Publication Date(Web):
DOI:10.1002/anie.201408862

Abstract

The controlled generation of singlet oxygen is of great interest owing to its potential applications including industrial wastewater treatment, photochemistry, and photodynamic therapy. Two photochromic metal–organic frameworks, PC-PCN and SO-PCN, have been developed. A photochromic reaction has been successfully realized in PC-PCN while maintaining its single crystallinity. In particular, as a solid-state material which inherently integrates the photochromic switch and photosensitizer, SO-PCN has demonstrated reversible control of 1O2 generation. Additionally, SO-PCN shows catalytic activity towards photooxidation of 1,5-dihydroxynaphthalene.

Co-reporter:Jihye Park;Dawei Feng;Shuai Yuan ;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2015 Volume 54( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/anie.201580261
Co-reporter:Weigang Lu, Zhangwen Wei, Zhi-Yuan Gu, Tian-Fu Liu, Jinhee Park, Jihye Park, Jian Tian, Muwei Zhang, Qiang Zhang, Thomas Gentle III, Mathieu Bosch and Hong-Cai Zhou  
Chemical Society Reviews 2014 vol. 43(Issue 16) pp:5561-5593
Publication Date(Web):06 Mar 2014
DOI:10.1039/C4CS00003J
Metal–organic frameworks (MOFs) are constructed from metal ions/clusters coordinated by organic linkers (or bridging-ligands). The hallmark of MOFs is their permanent porosity, which is frequently found in MOFs constructed from metal-clusters. These clusters are often formed in situ, whereas the linkers are generally pre-formed. The geometry and connectivity of a linker dictate the structure of the resulting MOF. Adjustments of linker geometry, length, ratio, and functional-group can tune the size, shape, and internal surface property of a MOF for a targeted application. In this critical review, we highlight advances in MOF synthesis focusing on linker design. Examples of building MOFs to reach unique properties, such as unprecedented surface area, pore aperture, molecular recognition, stability, and catalysis, through linker design are described. Further search for application-oriented MOFs through judicious selection of metal clusters and organic linkers is desirable. In this review, linkers are categorized as ditopic (Section 1), tritopic (Section 2), tetratopic (Section 3), hexatopic (Section 4), octatopic (Section 5), mixed (Section 6), desymmetrized (Section 7), metallo (Section 8), and N-heterocyclic linkers (Section 9).
Co-reporter:Kecheng Wang ; Dawei Feng ; Tian-Fu Liu ; Jie Su ; Shuai Yuan ; Ying-Pin Chen ; Mathieu Bosch ; Xiaodong Zou
Journal of the American Chemical Society 2014 Volume 136(Issue 40) pp:13983-13986
Publication Date(Web):September 10, 2014
DOI:10.1021/ja507269n
A series of mesoporous metalloporphyrin Fe-MOFs, namely PCN-600(M) (M = Mn, Fe, Co, Ni, Cu), have been synthesized using the preassembled [Fe3O(OOCCH3)6] building block. PCN-600 exhibits a one-dimensional channel as large as 3.1 nm and the highest experimental pore volume of 1.80 cm3g–1 among all the reported porphyrinic MOFs. It also shows very high stability in aqueous solutions with pH values ranging from 2–11 and is to our knowledge the only mesoporous porphyrinic MOF stable under basic aqueous conditions. PCN-600(Fe) has been demonstrated as an effective peroxidase mimic to catalyze the co-oxidation reaction.
Co-reporter:Weigang Lu, Zhangwen Wei, Daqiang Yuan, Jian Tian, Stephen Fordham, and Hong-Cai Zhou
Chemistry of Materials 2014 Volume 26(Issue 15) pp:4589
Publication Date(Web):July 20, 2014
DOI:10.1021/cm501922h
Head-on polymerization of tetrahedral monomers inherently imparts interconnected diamond cages to the resulting framework with each strut widely exposed. We have designed and synthesized a series of 3,3′,5,5′-tetraethynylbiphenyl monomers, in which the two phenyl rings are progressively locked into a nearly perpendicular position by adding substituents of different size at 2, 2′, 6, and 6′ positions, as evident from single crystal structures. Computational simulation suggests that these monomers, though not perfectly regular tetrahedra, could still be self-polymerized into three-dimensional frameworks with the same topology. Indeed, five porous polymer networks (PPNs) have been successfully synthesized with these newly designed monomers through Cu(II)-promoted Eglinton homocoupling reaction. Among them, PPN-13 shows exceptionally high Brunauer–Emmett–Teller (BET) surface area of 3420 m2/g. The total hydrogen uptake is 52 mg/g at 40 bar and 77 K, and the total methane uptake is 179 mg/g at 65 bar and 298 K.
Co-reporter:Andrey A. Yakovenko, Zhangwen Wei, Mario Wriedt, Jian-Rong Li, Gregory J. Halder, and Hong-Cai Zhou
Crystal Growth & Design 2014 Volume 14(Issue 11) pp:5397-5407
Publication Date(Web):September 29, 2014
DOI:10.1021/cg500525g
The structural characterization of metal–organic frameworks (MOFs) by powder X-ray diffraction can be challenging. Even more difficult are studies of guest solvent or gas molecules inside the MOF pores. Hence, recently we successfully designed several new approaches for structural investigations of porous MOFs. These methods use structure envelopes, which can be easily generated from the structure factors of a few (1–10) of the most intense low index reflections. However, the most interesting results have been found by using difference envelope density (DED) analysis. DED can be produced by taking the difference between observed and calculated structure envelope densities. The generation and analysis of DED maps are straightforward but allow studying guest molecules in the pores of MOFs by using routine powder X-ray diffraction data. Examples of DED used for studies of solvent molecule location, porosity activation, and gas loading are presented herein. We show that DED analysis is an important technique in the study of host–guest properties in MOFs by providing position, shape, and approximate occupancy of molecules in the MOF pores.
Co-reporter:Muwei Zhang;Ying-Pin Chen;Mathieu Bosch;Thomas Gentle III;Kecheng Wang;Dawei Feng;Dr. Zhiyong U. Wang;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2014 Volume 53( Issue 3) pp:815-818
Publication Date(Web):
DOI:10.1002/anie.201307340

Abstract

Two stable, non-interpenetrated MOFs, PCN-521 and PCN-523, were synthesized by a symmetry-guided strategy. Augmentation of the 4-connected nodes in the fluorite structure with a rigid tetrahedral ligand and substitution of the 8-connected nodes by the Zr/Hf clusters yielded MOFs with large octahedral interstitial cavities. They are the first examples of Zr/Hf MOFs with tetrahedral linkers. PCN-521 has the largest BET surface area (3411 m2 g-1), pore size (20.5×20.5×37.4 Å) and void volume (78.5%) of MOFs formed from tetrahedral ligands. This work not only demonstrates a successful implementation of rational design of MOFs with desired topology, but also provides a systematic way of constructing non-interpenetrated MOFs with high porosity.

Co-reporter:Muwei Zhang;Ying-Pin Chen;Mathieu Bosch;Thomas Gentle III;Kecheng Wang;Dawei Feng;Dr. Zhiyong U. Wang;Dr. Hong-Cai Zhou
Angewandte Chemie 2014 Volume 126( Issue 3) pp:834-837
Publication Date(Web):
DOI:10.1002/ange.201307340

Abstract

Two stable, non-interpenetrated MOFs, PCN-521 and PCN-523, were synthesized by a symmetry-guided strategy. Augmentation of the 4-connected nodes in the fluorite structure with a rigid tetrahedral ligand and substitution of the 8-connected nodes by the Zr/Hf clusters yielded MOFs with large octahedral interstitial cavities. They are the first examples of Zr/Hf MOFs with tetrahedral linkers. PCN-521 has the largest BET surface area (3411 m2 g-1), pore size (20.5×20.5×37.4 Å) and void volume (78.5%) of MOFs formed from tetrahedral ligands. This work not only demonstrates a successful implementation of rational design of MOFs with desired topology, but also provides a systematic way of constructing non-interpenetrated MOFs with high porosity.

Co-reporter:Julian P. Sculley;Wolfgang M. Verdegaal;Weigang Lu;Mario Wriedt
Advanced Materials 2013 Volume 25( Issue 29) pp:3957-3961
Publication Date(Web):
DOI:10.1002/adma.201204695
Co-reporter:Julian P. Sculley;Wolfgang M. Verdegaal;Weigang Lu;Mario Wriedt
Advanced Materials 2013 Volume 25( Issue 29) pp:
Publication Date(Web):
DOI:10.1002/adma.201370184
Co-reporter:Mario Wriedt ; Andrey A. Yakovenko ; Gregory J. Halder ; Andrey V. Prosvirin ; Kim R. Dunbar
Journal of the American Chemical Society 2013 Volume 135(Issue 10) pp:4040-4050
Publication Date(Web):February 15, 2013
DOI:10.1021/ja312347p
Hydrothermal reactions of copper(II) acetate, tetrazolate-5-carboxylate (tzc), and the neutral N-donor spacer ligand 1,3-di(4-pyridyl)propane (dpp) lead in a single reaction vial to the simultaneous formation of three different single-crystalline solvates [Cu(tzc)(dpp)]n·0.5C6H14·0.5H2O (1), [Cu(tzc)(dpp)]n·4.5H2O (2), and [Cu(tzc)(dpp)]n·1.25C6H14 (3). All three structures were characterized by single crystal X-ray diffraction. None of these solvates can be prepared as phase-pure bulk materials, but reaction conditions similar to those used for single crystal synthesis yield a phase-pure polycrystalline bulk material of an additional forth solvate phase [Cu(tzc)(dpp)]n·2H2O (4). Investigations of its thermal properties by in situ temperature-dependent synchrotron-based powder diffraction experiments have shown interesting phase transitions upon heating in a helium stream. Initially, the precursor dihydrate 4 transforms to an anhydrous phase [Cu(tzc)(dpp)]n (6I) via the intermediate monohydrate phase [Cu(tzc)(dpp)]n·H2O (5). Upon further heating, phase 6I transforms to a new anhydrous polymorph 6II, which transforms upon cooling to a further new phase 6III. Thermogravimetric measurements performed in tandem with differential scanning calorimetry as well as infrared spectroscopic investigations are in agreement with these findings. The de/resolvation behavior is accompanied by a dramatic change in their magnetic properties: The dihydrate phase shows antiferromagnetic exchange interactions, whereas ferromagnetic properties are observed for the trimorphic anhydrate system. This magnetic sponge-like behavior can be reversibly cycled upon de/resolvation of the material.
Co-reporter:Trevor A. Makal, Wenjuan Zhuang and Hong-Cai Zhou  
Journal of Materials Chemistry A 2013 vol. 1(Issue 43) pp:13502-13509
Publication Date(Web):10 Sep 2013
DOI:10.1039/C3TA12761C
Two newly designed semi-flexible tetratopic carboxylate ligands, 5′,5′′′′-(propane-2,2-diyl)bis(2′-methoxy-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylate) (pbtd-OMe4−) and 5′,5′′′′-(propane-2,2-diyl)bis(2′-ethoxy-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylate) (pbtd-OEt4−), have been used to connect dicopper paddlewheel building units to afford two isostructural metal–organic frameworks, Cu2(H2O)2(pbtd-OR)·xS (R = Me, PCN-38·xS; R = Et, PCN-39·xS, S represents noncoordinated guest molecules, PCN = porous coordination network) with novel structure and gas sorption properties upon activation. PCN-39 undergoes structural transformations upon guest solvent removal, leading to observation of distinct phases from in situ powder X-ray diffraction measurements, and exhibits selective adsorption of H2 (up to 2.0 wt%) over CO, CO2, and N2, which can be explained by optimized space-filling of the pendant ethoxy group. PCN-38 undergoes no transformation upon activation and exhibits hydrogen uptake up to 2.2 wt%, as well as moderate uptake of other gases. The selective adsorption of hydrogen over other gases highlights the potential application of PCN-39 in industrially important gas separation.
Co-reporter:Dawei Feng ; Hai-Long Jiang ; Ying-Pin Chen ; Zhi-Yuan Gu ; Zhangwen Wei
Inorganic Chemistry 2013 Volume 52(Issue 21) pp:12661-12667
Publication Date(Web):October 22, 2013
DOI:10.1021/ic4018536
The ongoing study of zirconium– and hafnium–porphyrinic metal–organic frameworks (MOFs) led to the discovery of isostructural MOFs based on Zr8 and Hf8 clusters, which are unknown in both cluster and MOF chemistry. The Zr8O6 cluster features an idealized Zr8 cube, in which each Zr atom resides on one vertex and each face of the cube is capped by one μ4-oxygen atom. On each edge of the cube, a carboxylate from a porphyrinic ligand bridges two Zr atoms to afford a 3D MOF with a very rare (4,12)-connected ftw topology, in which two types of polyhedral cages with diameters of ∼1.1 and ∼2.0 nm and a cage opening of ∼0.8 nm are found. The isostructural Zr– and Hf–MOFs exhibit high surface areas, gas uptakes, and catalytic selectivity for cyclohexane oxidation.
Co-reporter:Trevor A. Makal, Xuan Wang, and Hong-Cai Zhou
Crystal Growth & Design 2013 Volume 13(Issue 11) pp:4760-4768
Publication Date(Web):September 13, 2013
DOI:10.1021/cg4009224
An isostructural series of NbO-type porous metal–organic frameworks (MOFs) with different dialkoxy-substituents of formula Cu2(TPTC-OR) (TPTC-OR = 2′,5′-di{alkyl}oxy-[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylate, R = Me, Et, nPr, nHex) has been synthesized and characterized. The moisture stability of the materials has been evaluated, and a new superhydrophobic porous MOF has been identified. The relationship between pendant side chain length and thermal stability has been analyzed by in situ synchrotron powder X-ray diffraction, showing decreased thermal stability as the side chain length is increased, contradictory to thermogravimetric decomposition studies. Additionally, the four materials exhibit moderate Brunauer–Emmett–Teller (BET) and Langmuir surface areas (1127–1396 m2 g–1 and 1414–1658 m2 g–1) and H2 capacity up to 1.9 wt % at 77 K and 1 bar.
Co-reporter:Yangyang Liu, Ying-Pin Chen, Tian-Fu Liu, Andrey A. Yakovenko, Aaron M. Raiff and Hong-Cai Zhou  
CrystEngComm 2013 vol. 15(Issue 45) pp:9688-9693
Publication Date(Web):29 Aug 2013
DOI:10.1039/C3CE41106K
A 3D Magnesium MOF PCN-72 has been synthesized from the solvothermal reaction of Mg(NO3)2 and a linear ligand. This MOF has a unique structure with 1-dimensional (1D) channel as well as infinite metal chains, which resembles the topology of MIL-53. It is thermally and moisture stable. In situ powder X-ray diffraction studies reveal its interesting phase transitions under temperature change. Calculation shows that each phase of PCN-72 exhibits unique and unusual thermal expansion properties. After removing coordinated solvent at Mg chains, PCN-72 can selectively adsorb CO2 over N2.
Co-reporter:Trevor A. Makal, Jian-Rong Li, Weigang Lu and Hong-Cai Zhou  
Chemical Society Reviews 2012 vol. 41(Issue 23) pp:7761-7779
Publication Date(Web):18 Sep 2012
DOI:10.1039/C2CS35251F
The need for alternative fuels is greater now than ever before. With considerable sources available and low pollution factor, methane is a natural choice as petroleum replacement in cars and other mobile applications. However, efficient storage methods are still lacking to implement the application of methane in the automotive industry. Advanced porous materials, metal–organic frameworks and porous organic polymers, have received considerable attention in sorptive storage applications owing to their exceptionally high surface areas and chemically-tunable structures. In this critical review we provide an overview of the current status of the application of these two types of advanced porous materials in the storage of methane. Examples of materials exhibiting high methane storage capacities are analyzed and methods for increasing the applicability of these advanced porous materials in methane storage technologies described.
Co-reporter:Jinhee Park, Jian-Rong Li, Ying-Pin Chen, Jiamei Yu, Andrey A. Yakovenko, Zhiyong U. Wang, Lin-Bing Sun, Perla B. Balbuena and Hong-Cai Zhou  
Chemical Communications 2012 vol. 48(Issue 80) pp:9995-9997
Publication Date(Web):22 Aug 2012
DOI:10.1039/C2CC34622B
A multi-functional MOF PCN-124 was constructed from Cu paddlewheel motifs and a judiciously designed novel ligand bearing carboxylate, pyridine, and amide groups. PCN-124 exhibits selective adsorption of CO2 over CH4 and excellent catalytic activity in a tandem one-pot deacetalization–Knoevenagel condensation reaction as a cooperative catalyst.
Co-reporter:Jinhee Park, Jian-Rong Li, E. Carolina Sañudo, Daqiang Yuan and Hong-Cai Zhou  
Chemical Communications 2012 vol. 48(Issue 6) pp:883-885
Publication Date(Web):11 Nov 2011
DOI:10.1039/C1CC16261F
A metal–organic framework (MOF) with helical channels has been constructed by bridging helical chain secondary building units with 2,6-di-p-carboxyphenyl-4,4′-bipyridine ligands. The activated MOF shows permanent porosity and gas adsorption selectivity. Remarkably, the MOF exhibits a facile transition from micro- to meso-porosity.
Co-reporter:Wenjuan Zhuang;Daqiang Yuan;Jian-Rong Li;Zhiping Luo;Sajid Bashir;Jingbo Liu
Advanced Healthcare Materials 2012 Volume 1( Issue 2) pp:225-238
Publication Date(Web):
DOI:10.1002/adhm.201100043

Abstract

Recent outbreaks of bacterial infection leading to human fatalities have been a motivational force for us to develop antibacterial agents with high potency and long-term stability. A novel cobalt (Co) based metal-organic framework (MOF) was tested and shown to be highly effective at inactivating model microorganisms. Gram-negative bacteria, Escherichia coli (strains DH5alpha and XL1-Blue) were selected to determine the antibacterial activities of the Co MOF. In this MOF, the Co serves as a central element and an octa-topic carboxylate ligand, tetrakis [(3,5-dicarboxyphenyl)-oxamethyl] methane (TDM8−) serves as a bridging linker. X-ray crystallographic studies indicate that Co-TDM crystallizes in tetragonal space group P21m with a porous 3D framework.

The potency of the Co-TDM disinfectant was evaluated using a minimal bactericidal concentration (MBC) benchmark and was determined to be 10–15 ppm within a short incubation time period (<60 min). Compared with previous work using silver nanoparticles and silver-modified TiO2 nano- composites over the same time period, the MBC and effectiveness of Co-TDM are superior. Electron microscopy images indicate that the Co-TDM displayed distinctive grain boundaries and well-developed reticulates. The Co active sites rapidly catalyzed the lipid peroxidation, causing rupture of the bacterial membrane followed by inactivation, with 100% recycling and high persistence (>4 weeks). This MOF-based approach may lead to a new paradigm for MOF applications in diverse biological fields due to their inherent porous structure, tunable surface functional groups, and adjustable metal coordination environments.

Co-reporter:Mario Wriedt and Hong-Cai “Joe” Zhou  
Dalton Transactions 2012 vol. 41(Issue 14) pp:4207-4216
Publication Date(Web):16 Jan 2012
DOI:10.1039/C2DT11965J
Reaction of copper(II) tetrazolate-5-carboxylate with different neutral N-donor spacer ligands under hydrothermal conditions leads to the formation of five new coordination polymers, [Cu(tzc)(pyz)0.5(H2O)2]n·H2O (1), [Cu(tzc)(pyz)]n (2), [Cu(tzc)(pym)(H2O)]n (3), [Cu(tzc)(dpe)0.5(H2O)]n (4) and [Cu(tzc)(azpy)0.5(H2O)]n (5) (tzc = tetrazolate-5-carboxylate, pyz = pyrazine, pym = pyrimidine, dpe = 1,2-di(4-pyridyl)ethylene and azpy = 4,4′-azopyridine). All five structures were characterized by X-ray single-crystal measurements and bulk material can be prepared phase pure in high yields. The crystal structures of the hydrates 1, 3, 4 and 5 show dimeric [Cu2(Ntzc–Ntzc)2] building units formed by μ2-N1,O1:N2 bridging tzc ligands as the characteristic structural motif. These six-membered entities in 1, 4 and 5 are connected by μ2-N,N′ bridging N-donor ligands into 1D chains and in 3 into 2D layers. In the crystal structure of compound 2 adjacent Cu(II) cations are connected by μ2-N1,O1:N4,O2 bridging tzc ligands into chains, which are further connected by μ2-N,N′ bridging pyz ligands forming 2D layers. Extensive hydrogen bonds in all compounds play an important role in the construction of their supramolecular networks. Investigations of their thermal properties reveal water release upon heating according to the formation of anhydrates before starting decomposing above 220 °C. Furthermore, the magnetic properties have been studied leading to consistent global antiferromagnetic exchange interactions with coupling constants of J = 3 ± 1 cm−1 and long-range antiferromagnetic ordering states at lower temperatures.
Co-reporter:Julian P. Sculley ;Dr. Hong-Cai Zhou
Angewandte Chemie 2012 Volume 124( Issue 51) pp:12830-12832
Publication Date(Web):
DOI:10.1002/ange.201207495
Co-reporter:Dr. Mario Wriedt;Julian P. Sculley;Andrey A. Yakovenko;Dr. Yuguang Ma;Dr. Gregory J. Halder;Dr. Perla B. Balbuena;Dr. Hong-Cai Zhou
Angewandte Chemie 2012 Volume 124( Issue 39) pp:9942-9946
Publication Date(Web):
DOI:10.1002/ange.201202992
Co-reporter:Julian P. Sculley ;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2012 Volume 51( Issue 51) pp:12660-12661
Publication Date(Web):
DOI:10.1002/anie.201207495
Co-reporter:Dawei Feng;Dr. Zhi-Yuan Gu;Dr. Jian-Rong Li;Dr. Hai-Long Jiang;Zhangwen Wei;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2012 Volume 51( Issue 41) pp:
Publication Date(Web):
DOI:10.1002/anie.201206772
Co-reporter:Dawei Feng;Dr. Zhi-Yuan Gu;Dr. Jian-Rong Li;Dr. Hai-Long Jiang;Zhangwen Wei;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2012 Volume 51( Issue 41) pp:10307-10310
Publication Date(Web):
DOI:10.1002/anie.201204475
Co-reporter:Dr. Mario Wriedt;Julian P. Sculley;Andrey A. Yakovenko;Dr. Yuguang Ma;Dr. Gregory J. Halder;Dr. Perla B. Balbuena;Dr. Hong-Cai Zhou
Angewandte Chemie International Edition 2012 Volume 51( Issue 39) pp:9804-9808
Publication Date(Web):
DOI:10.1002/anie.201202992
Co-reporter:Dawei Feng;Dr. Zhi-Yuan Gu;Dr. Jian-Rong Li;Dr. Hai-Long Jiang;Zhangwen Wei;Dr. Hong-Cai Zhou
Angewandte Chemie 2012 Volume 124( Issue 41) pp:10453-10456
Publication Date(Web):
DOI:10.1002/ange.201204475
Co-reporter:Dawei Feng;Dr. Zhi-Yuan Gu;Dr. Jian-Rong Li;Dr. Hai-Long Jiang;Zhangwen Wei;Dr. Hong-Cai Zhou
Angewandte Chemie 2012 Volume 124( Issue 41) pp:
Publication Date(Web):
DOI:10.1002/ange.201206772
Co-reporter:Lin-Bing Sun ; Jian-Rong Li ; Jinhee Park
Journal of the American Chemical Society 2011 Volume 134(Issue 1) pp:126-129
Publication Date(Web):December 13, 2011
DOI:10.1021/ja209698f
Despite great efforts, the development of a reliable way to assemble mesoporous metal–organic frameworks (mesoMOFs) remains a challenge. In this work, we have designed a cooperative template system, comprising a surfactant (cetyltrimethylammonium bromide) and a chelating agent (citric acid), for the generation of a mesoMOF containing a hierarchical system of mesopores interconnected with microspores. The surfactant molecules form micelles and the chelating agent bridges the MOF and the micelles, making self-assembly and crystal growth proceed under the direction of the cooperative template. However, when the surfactant or the chelating agent was applied individually, no mesoMOF was obtained.
Co-reporter:Jinhee Park ; Daqiang Yuan ; Khanh T. Pham ; Jian-Rong Li ; Andrey Yakovenko
Journal of the American Chemical Society 2011 Volume 134(Issue 1) pp:99-102
Publication Date(Web):December 13, 2011
DOI:10.1021/ja209197f
A metal–organic framework (MOF) for reversible alteration of guest molecule adsorption, here carbon dioxide, upon photochemical or thermal treatment has been discovered. An azobenzene functional group, which can switch its conformation upon light irradiation or heat treatment, has been introduced to the organic linker of a MOF. The resulting MOF adsorbs different amount of CO2 after UV or heat treatment. This remarkable stimuli-responsive adsorption effect has been demonstrated through experiments.
Co-reporter:Trevor A. Makal, Andrey A. Yakovenko, and Hong-Cai Zhou
The Journal of Physical Chemistry Letters 2011 Volume 2(Issue 14) pp:1682-1689
Publication Date(Web):June 28, 2011
DOI:10.1021/jz200424h
Metal–organic frameworks (MOFs) are very important in the development of new technologies and study of gas storage and separation. MOFs are based on the complexation of metal clusters with organic ligands. Occasionally, the same building components combine in multiple different ways to produce different structures. These different structures are what we would call “framework isomers.” This type of isomerism is unique to the field of MOFs. In this Perspective, we classify the different types of framework isomers and provide examples of each type. Additionally, we provide an analysis of the structure/property relationship. In addition, possible methods for future control over the synthesis of a particular framework isomer and characterization techniques have also been discussed.
Co-reporter:Jun-Sheng Qin, Shuai Yuan, Qi Wang, Ali Alsalme and Hong-Cai Zhou
Journal of Materials Chemistry A 2017 - vol. 5(Issue 9) pp:NaN4291-4291
Publication Date(Web):2017/01/27
DOI:10.1039/C6TA10281F
Owing to their permanent porosity, tunability and multifunctionalization, metal–organic framework (MOF) materials have captured widespread interest in various fields, including gas storage and separation, catalysis, and energy storage. However, precise control over the composition, structure and properties of MOF materials remains a generally elusive but worthwhile dream. The stepwise assembly of porous crystalline MOF materials provides possibility to access this goal. In this review, we focus on four kinds of mixed-linker MOFs, (i) pillared-layer mixed-linker MOFs, (ii) cage-directed mixed-linker MOFs, (iii) cluster-based mixed-linker MOFs, and (iv) structure templated mixed-linker MOFs. The achieved progress and existing problems are discussed, and the opportunities and challenges of mixed-linker MOFs and their related applications are anticipated.
Co-reporter:Jinhee Park, Jian-Rong Li, E. Carolina Sañudo, Daqiang Yuan and Hong-Cai Zhou
Chemical Communications 2012 - vol. 48(Issue 6) pp:NaN885-885
Publication Date(Web):2011/11/11
DOI:10.1039/C1CC16261F
A metal–organic framework (MOF) with helical channels has been constructed by bridging helical chain secondary building units with 2,6-di-p-carboxyphenyl-4,4′-bipyridine ligands. The activated MOF shows permanent porosity and gas adsorption selectivity. Remarkably, the MOF exhibits a facile transition from micro- to meso-porosity.
Co-reporter:Jinhee Park, Jian-Rong Li, Ying-Pin Chen, Jiamei Yu, Andrey A. Yakovenko, Zhiyong U. Wang, Lin-Bing Sun, Perla B. Balbuena and Hong-Cai Zhou
Chemical Communications 2012 - vol. 48(Issue 80) pp:NaN9997-9997
Publication Date(Web):2012/08/22
DOI:10.1039/C2CC34622B
A multi-functional MOF PCN-124 was constructed from Cu paddlewheel motifs and a judiciously designed novel ligand bearing carboxylate, pyridine, and amide groups. PCN-124 exhibits selective adsorption of CO2 over CH4 and excellent catalytic activity in a tandem one-pot deacetalization–Knoevenagel condensation reaction as a cooperative catalyst.
Co-reporter:Shuai Yuan, Tian-Fu Liu, Dawei Feng, Jian Tian, Kecheng Wang, Junsheng Qin, Qiang Zhang, Ying-Pin Chen, Mathieu Bosch, Lanfang Zou, Simon J. Teat, Scott J. Dalgarno and Hong-Cai Zhou
Chemical Science (2010-Present) 2015 - vol. 6(Issue 7) pp:NaN3930-3930
Publication Date(Web):2015/04/28
DOI:10.1039/C5SC00916B
We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal–organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.
Co-reporter:Lanfang Zou, Dawei Feng, Tian-Fu Liu, Ying-Pin Chen, Shuai Yuan, Kecheng Wang, Xuan Wang, Stephen Fordham and Hong-Cai Zhou
Chemical Science (2010-Present) 2016 - vol. 7(Issue 2) pp:NaN1069-1069
Publication Date(Web):2015/11/02
DOI:10.1039/C5SC03620H
Exploitation of new titanium metal–organic frameworks (Ti-MOFs) with high crystallinity has been attracting great attention due to their vast application potential in photocatalysis. Herein a versatile synthetic strategy, namely, High Valence Metathesis and Oxidation (HVMO), is developed to synthesize a series of Ti-MOFs with predesigned topologies and structures. The crystallinity of these Ti-MOFs was well maintained throughout, as confirmed by powder X-ray diffraction and gas adsorption measurements. Significantly, there were only a few examples of Ti-MOFs, not to mention a general synthetic strategy for various kinds of Ti-MOFs in the literature. This contribution also illustrates the intriguing potential of Ti-MOF platforms in photocatalysis.
Co-reporter:Xizhen Lian, Dawei Feng, Ying-Pin Chen, Tian-Fu Liu, Xuan Wang and Hong-Cai Zhou
Chemical Science (2010-Present) 2015 - vol. 6(Issue 12) pp:NaN7048-7048
Publication Date(Web):2015/09/02
DOI:10.1039/C5SC02587G
Kinetic labilization of the Fe(III)–O coordination bond in a mesoporous metal–organic framework, PCN-333-Fe(III), is realized by the reduction of Fe(III) by Cr(II). The Fe(II)–Cr(II) metathesis is thus completely achieved followed by this reductive labilization process that generates PCN-333-Cr(III). The kinetic inertness of Cr(III) provides PCN-333-Cr(III) with enhanced chemical stability as well as a broader range of applications compared to those of PCN-333-Fe(III). For instance, alkylamine incorporated PCN-333-Cr(III) demonstrated significant carbon dioxide uptake while PCN-333-Fe(III) lost its crystallinity after alkylamine treatment.
Co-reporter:Trevor A. Makal, Jian-Rong Li, Weigang Lu and Hong-Cai Zhou
Chemical Society Reviews 2012 - vol. 41(Issue 23) pp:NaN7779-7779
Publication Date(Web):2012/09/18
DOI:10.1039/C2CS35251F
The need for alternative fuels is greater now than ever before. With considerable sources available and low pollution factor, methane is a natural choice as petroleum replacement in cars and other mobile applications. However, efficient storage methods are still lacking to implement the application of methane in the automotive industry. Advanced porous materials, metal–organic frameworks and porous organic polymers, have received considerable attention in sorptive storage applications owing to their exceptionally high surface areas and chemically-tunable structures. In this critical review we provide an overview of the current status of the application of these two types of advanced porous materials in the storage of methane. Examples of materials exhibiting high methane storage capacities are analyzed and methods for increasing the applicability of these advanced porous materials in methane storage technologies described.
Co-reporter:Mario Wriedt and Hong-Cai “Joe” Zhou
Dalton Transactions 2012 - vol. 41(Issue 14) pp:NaN4216-4216
Publication Date(Web):2012/01/16
DOI:10.1039/C2DT11965J
Reaction of copper(II) tetrazolate-5-carboxylate with different neutral N-donor spacer ligands under hydrothermal conditions leads to the formation of five new coordination polymers, [Cu(tzc)(pyz)0.5(H2O)2]n·H2O (1), [Cu(tzc)(pyz)]n (2), [Cu(tzc)(pym)(H2O)]n (3), [Cu(tzc)(dpe)0.5(H2O)]n (4) and [Cu(tzc)(azpy)0.5(H2O)]n (5) (tzc = tetrazolate-5-carboxylate, pyz = pyrazine, pym = pyrimidine, dpe = 1,2-di(4-pyridyl)ethylene and azpy = 4,4′-azopyridine). All five structures were characterized by X-ray single-crystal measurements and bulk material can be prepared phase pure in high yields. The crystal structures of the hydrates 1, 3, 4 and 5 show dimeric [Cu2(Ntzc–Ntzc)2] building units formed by μ2-N1,O1:N2 bridging tzc ligands as the characteristic structural motif. These six-membered entities in 1, 4 and 5 are connected by μ2-N,N′ bridging N-donor ligands into 1D chains and in 3 into 2D layers. In the crystal structure of compound 2 adjacent Cu(II) cations are connected by μ2-N1,O1:N4,O2 bridging tzc ligands into chains, which are further connected by μ2-N,N′ bridging pyz ligands forming 2D layers. Extensive hydrogen bonds in all compounds play an important role in the construction of their supramolecular networks. Investigations of their thermal properties reveal water release upon heating according to the formation of anhydrates before starting decomposing above 220 °C. Furthermore, the magnetic properties have been studied leading to consistent global antiferromagnetic exchange interactions with coupling constants of J = 3 ± 1 cm−1 and long-range antiferromagnetic ordering states at lower temperatures.
Co-reporter:Lin-Bing Sun, Ai-Guo Li, Xiao-Dan Liu, Xiao-Qin Liu, Dawei Feng, Weigang Lu, Daqiang Yuan and Hong-Cai Zhou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 7) pp:NaN3256-3256
Publication Date(Web):2015/01/07
DOI:10.1039/C4TA06039C
Due to their synthetic diversification, low skeletal density, and high physicochemical stability, porous polymer networks (PPNs) are highly promising in a variety of applications such as carbon capture. Nevertheless, complicated monomers and/or expensive catalysts are normally utilized for their synthesis, which makes the process tedious, costly, and hard to scale up. In this study, a facile nucleophilic substitution reaction was designed to fabricate PPNs from low-cost monomers, namely chloromethyl benzene and ethylene diamine. A surfactant template was also used to direct the assembly, leading to the formation of PPN with enhanced porosity. It is fascinating that the polymerization reactions can occur at the low temperature of 63 °C in the absence of any catalyst. The obtained PPNs contain abundant secondary amines, which offer appropriate adsorbate–adsorbent interactions from the viewpoints of selective CO2 capture and energy-efficient regeneration of the adsorbents. Hence, these PPNs are highly active in selective adsorption of CO2, and unusually high CO2/N2 and CO2/CH4 selectivity was obtained. Moreover, the PPN adsorbents can be completely regenerated under mild conditions.
Co-reporter:Trevor A. Makal, Wenjuan Zhuang and Hong-Cai Zhou
Journal of Materials Chemistry A 2013 - vol. 1(Issue 43) pp:NaN13509-13509
Publication Date(Web):2013/09/10
DOI:10.1039/C3TA12761C
Two newly designed semi-flexible tetratopic carboxylate ligands, 5′,5′′′′-(propane-2,2-diyl)bis(2′-methoxy-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylate) (pbtd-OMe4−) and 5′,5′′′′-(propane-2,2-diyl)bis(2′-ethoxy-[1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylate) (pbtd-OEt4−), have been used to connect dicopper paddlewheel building units to afford two isostructural metal–organic frameworks, Cu2(H2O)2(pbtd-OR)·xS (R = Me, PCN-38·xS; R = Et, PCN-39·xS, S represents noncoordinated guest molecules, PCN = porous coordination network) with novel structure and gas sorption properties upon activation. PCN-39 undergoes structural transformations upon guest solvent removal, leading to observation of distinct phases from in situ powder X-ray diffraction measurements, and exhibits selective adsorption of H2 (up to 2.0 wt%) over CO, CO2, and N2, which can be explained by optimized space-filling of the pendant ethoxy group. PCN-38 undergoes no transformation upon activation and exhibits hydrogen uptake up to 2.2 wt%, as well as moderate uptake of other gases. The selective adsorption of hydrogen over other gases highlights the potential application of PCN-39 in industrially important gas separation.
Co-reporter:Weigang Lu, Zhangwen Wei, Zhi-Yuan Gu, Tian-Fu Liu, Jinhee Park, Jihye Park, Jian Tian, Muwei Zhang, Qiang Zhang, Thomas Gentle III, Mathieu Bosch and Hong-Cai Zhou
Chemical Society Reviews 2014 - vol. 43(Issue 16) pp:NaN5593-5593
Publication Date(Web):2014/03/06
DOI:10.1039/C4CS00003J
Metal–organic frameworks (MOFs) are constructed from metal ions/clusters coordinated by organic linkers (or bridging-ligands). The hallmark of MOFs is their permanent porosity, which is frequently found in MOFs constructed from metal-clusters. These clusters are often formed in situ, whereas the linkers are generally pre-formed. The geometry and connectivity of a linker dictate the structure of the resulting MOF. Adjustments of linker geometry, length, ratio, and functional-group can tune the size, shape, and internal surface property of a MOF for a targeted application. In this critical review, we highlight advances in MOF synthesis focusing on linker design. Examples of building MOFs to reach unique properties, such as unprecedented surface area, pore aperture, molecular recognition, stability, and catalysis, through linker design are described. Further search for application-oriented MOFs through judicious selection of metal clusters and organic linkers is desirable. In this review, linkers are categorized as ditopic (Section 1), tritopic (Section 2), tetratopic (Section 3), hexatopic (Section 4), octatopic (Section 5), mixed (Section 6), desymmetrized (Section 7), metallo (Section 8), and N-heterocyclic linkers (Section 9).
Co-reporter:Xizhen Lian, Yu Fang, Elizabeth Joseph, Qi Wang, Jialuo Li, Sayan Banerjee, Christina Lollar, Xuan Wang and Hong-Cai Zhou
Chemical Society Reviews 2017 - vol. 46(Issue 11) pp:NaN3401-3401
Publication Date(Web):2017/04/28
DOI:10.1039/C7CS00058H
The ex vivo application of enzymes in various processes, especially via enzyme immobilization techniques, has been extensively studied in recent years in order to enhance the recyclability of enzymes, to minimize enzyme contamination in the product, and to explore novel horizons for enzymes in biomedical applications. Possessing remarkable amenability in structural design of the frameworks as well as almost unparalelled surface tunability, Metal–Organic Frameworks (MOFs) have been gaining popularity as candidates for enzyme immobilization platforms. Many MOF–enzyme composites have achieved unprecedented results, far outperforming free enzymes in many aspects. This review summarizes recent developments of MOF–enzyme composites with special emphasis on preparative techniques and the synergistic effects of enzymes and MOFs. The applications of MOF–enzyme composites, primarily in transferation, catalysis and sensing, are presented as well. The enhancement of enzymatic activity of the composites over free enzymes in biologically incompatible conditions is emphasized in many cases.
Co-reporter:Xizhen Lian, Ying-Pin Chen, Tian-Fu Liu and Hong-Cai Zhou
Chemical Science (2010-Present) 2016 - vol. 7(Issue 12) pp:NaN6973-6973
Publication Date(Web):2016/07/14
DOI:10.1039/C6SC01438K
A hierarchical porous metal–organic framework (MOF), PCN-888, containing three types of cavities was utilized to couple two enzymes into a tandem nanoreactor. The largest cavity (6.2 nm) can only accommodate one molecule of glucose oxidase (GOx). The intermediate cavity (5.0 nm) can accommodate one and only one molecule of horseradish peroxidase (HRP). The small cavity (2.0 nm) has sufficient size for neither GOx nor HRP, and remains open as a substrate diffusion pathway. The coupling of the two enzymes can only be achieved through a unique stepwise encapsulation with a specific order (GOx first, followed by HRP). The tandem nanoreactor shows excellent catalytic performances and negligible enzyme leaching. Its catalytic activity is well maintained within several catalytic cycles. Moreover, PCN-888 can provide protection to the encapsulated enzymes against trypsin digestion, indicating the in vitro and in vivo stability of the nanoreactor.
Co-reporter:Lin-Bing Sun, Xiao-Qin Liu and Hong-Cai Zhou
Chemical Society Reviews 2015 - vol. 44(Issue 15) pp:NaN5147-5147
Publication Date(Web):2015/06/05
DOI:10.1039/C5CS00090D
Mesoporous solid bases are extremely desirable in green catalytic processes, due to their advantages of accelerated mass transport, negligible corrosion, and easy separation. Great progress has been made in mesoporous solid bases in the last decade. In addition to their wide applications in the catalytic synthesis of organics and fine chemicals, mesoporous solid bases have also been used in the field of energy and environmental catalysis. Development of mesoporous solid bases is therefore of significant importance from both academic and practical points of view. In this review, we provide an overview of the recent advances in mesoporous solid bases, which is basically grouped by the support type and each category is illustrated with typical examples. Cooperative catalysts derived from the incorporation of additional functionalities (i.e. acid and metal) into mesoporous solid bases are also included. The fundamental principles of how to design and fabricate basic materials with mesostructure are highlighted. The mechanism of the formation of basic sites in different mesoporous systems is discussed as well.
Co-reporter:Xuan Wang, Weigang Lu, Zhi-Yuan Gu, Zhangwen Wei and Hong-Cai Zhou
Chemical Communications 2016 - vol. 52(Issue 9) pp:NaN1929-1929
Publication Date(Web):2015/12/01
DOI:10.1039/C5CC08614K
An anionic metal–organic framework, PCN-99, has been synthesized through a topology-guided strategy; its underlying bor-net is realized by the use of a tetrahedral [In(COO)4]− node and a judiciously designed trigonal planar linker. In light of its anionic nature, the inherent cuboctahedral cage and 1D channel make PCN-99 an excellent matrix to encapsulate the photocatalytic [Ru(bpy)3]2+.
Mg-MOF-74
PCN-224(Ni)
PCN-224
2',5'-dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid
PCN-225(Zn)
[1,1':3',1''-Terphenyl]-3,3'',5,5''-tetracarboxylic acid
[1,1-Biphenyl]-3,5-dicarboxylic acid, 4-[1,2,2-tris(3,5-dicarboxy[1,1-biphenyl]-4-yl)ethenyl]-
PCN-82