Co-reporter:Rungmai Limvorapitux, Lien-Yang Chou, Allison P. Young, Chia-Kuang Tsung, and SonBinh T. Nguyen
ACS Catalysis October 6, 2017 Volume 7(Issue 10) pp:6691-6691
Publication Date(Web):July 26, 2017
DOI:10.1021/acscatal.6b03632
A molecular catalyst, (sal)MoVI, and a heterogeneous catalyst, either Pd or Au nanoparticles (NPs), were integrated into one UiO-66 MOF microcrystal. The resulting dually functionalized catalysts, Pd@UiO-66-(sal)Mo and Au/UiO-66-(sal)Mo, have been utilized for a one-pot tandem reaction of H2O2 generation and selective liquid-phase alkene oxidation. The NPs serve as catalysts for the production of H2O2 from H2 and O2 gases, while the (sal)Mo moieties function as the oxidation catalyst. When the metal NPs are fully encapsulated within the MOF microcrystals, the alkene hydrogenation side reaction is largely suppressed, with a 6-fold decrease in the hydrogenation/oxidation product ratio for 5-bromo-1-cyclooctene favoring the epoxide as the major product. For Au/UiO-66-(sal)Mo, where the two catalysts are in close proximity on the MOF microcrystal, the enhancement in oxidation productivity is increased by 10 times in comparison to the [Au/UiO-66-NH2 + UiO-66-sal(Mo)] physical mixture of the two singly functionalized MOFs.Keywords: alkene oxidation; in situ H2O2 generation; metal−organic framework; tandem reaction; UiO-66;
Co-reporter:Rungmai Limvorapitux, Lien-Yang Chou, Allison P. Young, Chia-Kuang Tsung, and SonBinh T. Nguyen
ACS Catalysis October 6, 2017 Volume 7(Issue 10) pp:6691-6691
Publication Date(Web):July 26, 2017
DOI:10.1021/acscatal.6b03632
A molecular catalyst, (sal)MoVI, and a heterogeneous catalyst, either Pd or Au nanoparticles (NPs), were integrated into one UiO-66 MOF microcrystal. The resulting dually functionalized catalysts, Pd@UiO-66-(sal)Mo and Au/UiO-66-(sal)Mo, have been utilized for a one-pot tandem reaction of H2O2 generation and selective liquid-phase alkene oxidation. The NPs serve as catalysts for the production of H2O2 from H2 and O2 gases, while the (sal)Mo moieties function as the oxidation catalyst. When the metal NPs are fully encapsulated within the MOF microcrystals, the alkene hydrogenation side reaction is largely suppressed, with a 6-fold decrease in the hydrogenation/oxidation product ratio for 5-bromo-1-cyclooctene favoring the epoxide as the major product. For Au/UiO-66-(sal)Mo, where the two catalysts are in close proximity on the MOF microcrystal, the enhancement in oxidation productivity is increased by 10 times in comparison to the [Au/UiO-66-NH2 + UiO-66-sal(Mo)] physical mixture of the two singly functionalized MOFs.Keywords: alkene oxidation; in situ H2O2 generation; metal−organic framework; tandem reaction; UiO-66;
Co-reporter:Resham J. Banga, Sai Archana Krovi, Suguna P. Narayan, Anthony J. Sprangers, Guoliang LiuChad A. Mirkin, SonBinh T. Nguyen
Biomacromolecules 2017 Volume 18(Issue 2) pp:
Publication Date(Web):December 8, 2016
DOI:10.1021/acs.biomac.6b01563
Small-sized (∼65 nm) doxorubicin (Dox)-loaded polymeric nanoparticles (PNPs) were modified with oligonucleotides to form colloidally stable Dox-loaded polymeric spherical nucleic acid (Dox-PSNA) nanostructures in biological media. The nucleic acid shell facilitates the cellular uptake of Dox-PSNA, which results in in vitro cytotoxicity against SKOV3 cancer cells.
Co-reporter:Vincent Y. Cho;Bong Jin Hong;Kevin L. Kohlstedt;George C. Schatz
Nanoscale (2009-Present) 2017 vol. 9(Issue 34) pp:12652-12663
Publication Date(Web):2017/08/31
DOI:10.1039/C7NR01931A
The nanoassembly behavior of trivalent small molecule-DNA hybrids (SMDH3s) was investigated as a function of core geometry and supramolecular flexibility through a synergistic experimental-modeling study. While complementary SMDH3s possessing a highly flexible tetrahedral trivalent core primarily assemble into nanoscale caged dimers, the nanoassemblies of SMDH3 comonomers with rigid pyramidal and trigonal cores yield fewer caged dimers and more large-oligomer networks. Specifically, the rigid pyramidal SMDH3 comonomers tend to form smaller nanosized aggregates (dimers, tetramers, and hexamers) upon assembly, attributable to the small (<109°) branch-core-branch angle of the pyramidal core. In contrast, the more-rigid trigonal planar SMDH3 comonomers have a larger (∼120°) branch-core-branch angle, which spaces their DNA arms farther apart, facilitating the formation of larger nanoassemblies (≥nonamers). The population distributions of these nanoassemblies were successfully captured by coarse-grained molecular dynamics (CGMD) simulations over a broad range of DNA concentrations. CGMD simulations can also forecast the effect of incorporating Tn spacer units between the hydridizing DNA arms and the rigid organic cores to increase the overall flexibility of the SMDH3 comonomers. Such “decoupling” of the DNA arms from the organic core was found to result in preferential formation of nanoscale dimers up to an optimal spacer length, beyond which network formation takes over due to entropic factors. This excellent agreement between the simulation and experimental results confirms the versatility of the CGMD model as a useful and reliable tool for elucidating the nanoassembly of SMDH-based building blocks.
Co-reporter:Andrea D. Merg;Ryan V. Thaner;Soumitra Mokashi-Punekar;Nathaniel L. Rosi
Chemical Communications 2017 vol. 53(Issue 90) pp:12221-12224
Publication Date(Web):2017/11/09
DOI:10.1039/C7CC07708D
Triblock peptide–oligonucleotide chimeras (POCs) consisting of peptides and oligonucleotides interlinked by an organic core are presented and their assembly behaviour is investigated. Several factors influence POC assembly, resulting in the formation of either vesicles or fibres. Design rules are introduced and used to predict and alter POC assembly morphology.
Co-reporter:Ryan V. Thaner; Ibrahim Eryazici; Robert J. Macfarlane; Keith A. Brown; Byeongdu Lee; SonBinh T. Nguyen;Chad A. Mirkin
Journal of the American Chemical Society 2016 Volume 138(Issue 19) pp:6119-6122
Publication Date(Web):May 5, 2016
DOI:10.1021/jacs.6b02479
Multivalent oligonucleotide-based bonding elements have been synthesized and studied for the assembly and crystallization of gold nanoparticles. Through the use of organic branching points, divalent and trivalent DNA linkers were readily incorporated into the oligonucleotide shells that define DNA-nanoparticles and compared to monovalent linker systems. These multivalent bonding motifs enable the change of “bond strength” between particles and therefore modulate the effective “bond order.” In addition, the improved accessibility of strands between neighboring particles, either due to multivalency or modifications to increase strand flexibility, gives rise to superlattices with less strain in the crystallites compared to traditional designs. Furthermore, the increased availability and number of binding modes also provide a new variable that allows previously unobserved crystal structures to be synthesized, as evidenced by the formation of a thorium phosphide superlattice.
Co-reporter:Michael R. Roenbeck, Al’ona Furmanchuk, Zhi An, Jeffrey T. Paci, Xiaoding Wei, SonBinh T. Nguyen, George C. Schatz, and Horacio D. Espinosa
Nano Letters 2015 Volume 15(Issue 7) pp:4504-4516
Publication Date(Web):June 11, 2015
DOI:10.1021/acs.nanolett.5b01011
Weak interfilament van der Waals interactions are potentially a significant roadblock in the development of carbon nanotube- (CNT-) and graphene-based nanocomposites. Chemical functionalization is envisioned as a means of introducing stronger intermolecular interactions at nanoscale interfaces, which in turn could enhance composite strength. This paper reports measurements of the adhesive energy of CNT–graphite interfaces functionalized with various coverages of arylpropionic acid. Peeling experiments conducted in situ in a scanning electron microscope show significantly larger adhesive energies compared to previously obtained measurements for unfunctionalized surfaces (Roenbeck et al. ACS Nano 2014, 8 (1), 124–138). Surprisingly, however, the adhesive energies are significantly higher when both surfaces have intermediate coverages than when one surface is densely functionalized. Atomistic simulations reveal a novel functional group interdiffusion mechanism, which arises for intermediate coverages in the presence of water. This interdiffusion is not observed when one surface is densely functionalized, resulting in energy trends that correlate with those observed in experiments. This unique intermolecular interaction mechanism, revealed through the integrated experimental–computational approach presented here, provides significant insights for use in the development of next-generation nanocomposites.
Co-reporter:Bong Jin Hong; Vincent Y. Cho; Reiner Bleher; George C. Schatz
Journal of the American Chemical Society 2015 Volume 137(Issue 41) pp:13381-13388
Publication Date(Web):September 23, 2015
DOI:10.1021/jacs.5b08678
Two complementary small-molecule–DNA hybrid (SMDH) building blocks have been combined to form well-defined supramolecular cage dimers at DNA concentrations as high as 102 μM. This was made possible by combining a flexible small-molecule core and three DNA arms of moderate lengths (<20 base pairs). These results were successfully modeled by coarse-grained molecular dynamics simulations, which also revealed that the formation of ill-defined networks in the case of longer DNA arms can be significantly biased by the presence of deep kinetic traps. Notably, melting point studies revealed that cooperative melting behavior can be used as a means to distinguish the relative propensities for dimer versus network formation from complementary flexible three-DNA-arm SMDH (fSMDH3) components: sharp, enhanced melting transitions were observed for assemblies that result mostly in cage dimers, while no cooperative melting behavior was observed for assemblies that form ill-defined networks.
Co-reporter:Bong Jin Hong; Ibrahim Eryazici; Reiner Bleher; Ryan V. Thaner; Chad A. Mirkin
Journal of the American Chemical Society 2015 Volume 137(Issue 25) pp:8184-8191
Publication Date(Web):May 17, 2015
DOI:10.1021/jacs.5b03485
Complementary tetrahedral small molecule-DNA hybrid (SMDH) building blocks have been combined to form nucleic acid-based polymeric nanoparticles without the need for an underlying template or scaffold. The sizes of these particles can be tailored in a facile fashion by adjusting assembly conditions such as SMDH concentration, assembly time, and NaCl concentration. Notably, these novel particles can be stabilized and transformed into functionalized spherical nucleic acid (SNA) structures through the incorporation of capping DNA strands conjugated with functional groups. These results demonstrate a systematic, efficient strategy for the construction and surface functionalization of well-defined, size-tunable nucleic acid particles from readily accessible molecular building blocks. Furthermore, because these nucleic acid-based polymeric nanoparticles exhibited enhanced cellular internalization and resistance to DNase I compared to free synthetic nucleic acids, they should have a plethora of applications in diagnostics and therapeutics.
Co-reporter:Sanjiban Chakraborty, Yamil J. Colón, Randall Q. Snurr and SonBinh T. Nguyen
Chemical Science 2015 vol. 6(Issue 1) pp:384-389
Publication Date(Web):16 Sep 2014
DOI:10.1039/C4SC02502D
Porous organic polymers (POPs) possessing meso- and micropores can be obtained by carrying out the polymerization inside a mesoporous silica aerogel template and then removing the template after polymerization. The total pore volume (tpv) and specific surface area (ssa) can be greatly enhanced by modifying the template (up to 210% increase for tpv and 73% for ssa) as well as by supercritical processing of the POPs (up to an additional 142% increase for tpv and an additional 32% for ssa) to include larger mesopores. The broad range of pores allows for faster transport of molecules through the hierarchically porous POPs, resulting in increased diffusion rates and faster gas uptake compared to POPs with only micropores.
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:Debashis Adhikari, Aaron W. Miller, Mu-Hyun Baik and SonBinh T. Nguyen
Chemical Science 2015 vol. 6(Issue 2) pp:1293-1300
Publication Date(Web):21 Nov 2014
DOI:10.1039/C4SC02785J
The (salen)Cr-catalyzed [aziridine + CO2] coupling to form oxazolidinone was found to exhibit excellent selectivity for the 5-substituted oxazolidinone product in the absence of any cocatalyst. Quantum mechanical calculations suggest that the preferential opening of the substituted C–N bond of the aziridine over the unsubstituted C–N bond is a key factor for this selectivity, a result that is supported by experiment with several phenyl-substituted aziridines. In the presence of external nucleophile such as dimethyl aminopyridine (DMAP), the reaction changes pathway and the ring-opening process is regulated by the steric demand of the nucleophile.
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:Huong Giang T. Nguyen, Lily Mao, Aaron W. Peters, Cornelius O. Audu, Zachary J. Brown, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Catalysis Science & Technology 2015 vol. 5(Issue 9) pp:4444-4451
Publication Date(Web):30 Jun 2015
DOI:10.1039/C5CY00825E
A comparative study of the support effect in three different UiO-66-based MOFs – with TiIV supported as part of the node (UiO-66-Tiex), attached to the node (Ti-UiO-66), and on a catecholate organic linker (UiO-66-Cat-Ti) – is reported. The three MOFs were evaluated for their catalytic activity and selectivity in cyclohexene oxidation. Ti-UiO-66 exhibited greater catalytic turnover numbers than UiO-66-Cat-Ti and UiO-66-Tiex.
Co-reporter:Resham J. Banga ; Natalia Chernyak ; Suguna P. Narayan ; SonBinh T. Nguyen ;Chad A. Mirkin
Journal of the American Chemical Society 2014 Volume 136(Issue 28) pp:9866-9869
Publication Date(Web):July 1, 2014
DOI:10.1021/ja504845f
A novel class of metal-free spherical nucleic acid nanostructures was synthesized from readily available starting components. These particles consist of 30 nm liposomal cores, composed of an FDA-approved 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid monomer. The surface of the liposomes was functionalized with DNA strands modified with a tocopherol tail that intercalates into the phospholipid layer of the liposomal core via hydrophobic interactions. The spherical nucleic acid architecture not only stabilizes these constructs but also facilitates cellular internalization and gene regulation in SKOV-3 cells.
Co-reporter:Allison M. Beese;Zhi An;Sourangsu Sarkar;S. Shiva P. Nathamgari;Horacio D. Espinosa
Advanced Functional Materials 2014 Volume 24( Issue 19) pp:2883-2891
Publication Date(Web):
DOI:10.1002/adfm.201303503
A biologically inspired, multilayer laminate structural design is deployed into nanocomposite films of graphene oxide-poly(methyl methacrylate) (GO-PMMA). The resulting multilayer GO-PMMA films show greatly enhanced mechanical properties compared to pure-graphene-oxide films, with up to 100% increases in stiffness and strength when optimized. Notably, a new morphology is observed at fracture surfaces: whereas pure-graphene-oxide films show clean fracture surfaces consistent with crack initiation and propagation perpendicular to the applied tensile load, the GO-PMMA multilayer laminates show terracing consistent with crack stopping and deflection mechanisms. As a consequence, these macroscopic GO-PMMA films become defect-tolerant and can maintain their tensile strengths as their sample volumes increase. Linear elastic fracture analysis supports these observations by showing that the stiffness modulation introduced by including PMMA layers within a graphene oxide film can act to shield or deflect cracks, thereby delaying failure and allowing the material to access more of its inherent strength. Together, these data clearly demonstrate that desirable defect-tolerant traits of structural biomaterials can indeed be incorporated into graphene- oxide-based nanocomposites.
Co-reporter:Ryan V. Thaner, Ibrahim Eryazici, Omar K. Farha, Chad A. Mirkin and SonBinh T. Nguyen
Chemical Science 2014 vol. 5(Issue 3) pp:1091-1096
Publication Date(Web):06 Dec 2013
DOI:10.1039/C3SC53206B
A broad range of synthetically challenging-to-access small molecule–DNA hybrids can be readily synthesized in “one pot” and in high yields by coupling multi-azide cores to alkyne-modified DNAs on a solid support using click chemistry. The multi-functional products can be obtained in pure forms and on large scales (1 μmol) in a facile fashion. In addition, the distribution of the products can be controlled by changing the concentration of the azide core in solution and the strand-loading density on the solid-supports.
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: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: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:Debashis Adhikari, SonBinh T. Nguyen and Mu-Hyun Baik
Chemical Communications 2014 vol. 50(Issue 20) pp:2676-2678
Publication Date(Web):07 Jan 2014
DOI:10.1039/C3CC48769E
Epoxide and CO2 coupling reactions catalyzed by (salen)CrIIICl have been modeled computationally to contrast a monometallic vs. a bimetallic mechanism. A low-energy CO2 insertion step into the metal–alkoxide bond was located.
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:Yalan Ning, Robert D. J .Froese, Peter Margl, Edward L. Lee, SonBinh T. Nguyen, Thomas H. Peterson, Nicole Wagner, Charlotte L. Stern, and Amy A. Sarjeant
Organometallics 2014 Volume 33(Issue 5) pp:1120-1125
Publication Date(Web):February 21, 2014
DOI:10.1021/om4006214
Zerovalent group 6 dinitrogen phosphine complexes react with 3,3-diphenylcyclopropene to give vinylcarbyne hydride complexes that have been characterized crystallographically. Computational studies indicate that the observed products resulted from the α-migration and rearrangement of an initially formed vinylcarbene.
Co-reporter:Zhi An, Al’ona Furmanchuk, Rajaprakash Ramachandramoorthy, Tobin Filleter, Michael R. Roenbeck, Horacio D. Espinosa, George C. Schatz, SonBinh T. Nguyen
Carbon 2014 80() pp: 1-11
Publication Date(Web):
DOI:10.1016/j.carbon.2014.07.069
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 2014 Volume 126( Issue 2) pp:507-511
Publication Date(Web):
DOI:10.1002/ange.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:Ilyas Yildirim, Ibrahim Eryazici, SonBinh T. Nguyen, and George C. Schatz
The Journal of Physical Chemistry B 2014 Volume 118(Issue 9) pp:2366-2376
Publication Date(Web):February 5, 2014
DOI:10.1021/jp501041m
Detailed computational and experimental studies reveal the crucial role that hydrophobic interactions play in the self-assembly of small molecule-DNA hybrids (SMDHs) into cyclic nanostructures. In aqueous environments, the distribution of the cyclic structures (dimers or higher-order structures) greatly depends on how well the hydrophobic surfaces of the organic cores in these nanostructures are minimized. Specifically, when the cores are attached to the 3′-ends of the DNA component strands, they can insert into the minor groove of the duplex that forms upon self-assembly, favoring the formation of cyclic dimers. However, when the cores are attached to the 5′-ends of the DNA component strands, such insertion is hindered, leading to the formation of higher-order cyclic structures. These computational insights are supported by experimental results that show clear differences in product distributions and stabilities for a broad range of organic core-linked DNA hybrids with different linkage directions and flexibilities.
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:Ryan K. Totten ; Ye-Seong Kim ; Mitchell H. Weston ; Omar K. Farha ; Joseph T. Hupp
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:Bong Jin Hong ; Anthony J. Chipre
Journal of the American Chemical Society 2013 Volume 135(Issue 47) pp:17655-17658
Publication Date(Web):September 3, 2013
DOI:10.1021/ja404491r
An acid-degradable polymer-caged lipoplex (PCL) platform consisting of a cationic lipoplex core and a biocompatible, pH-responsive polymer shell has been developed for the effective delivery of small interfering RNA (siRNA) through a combination of facile loading, rapid acid-triggered release, cellular internalization, and effective endosomal escape. In vitro testing of this degradable PCL delivery platform reveals ∼45- and ∼2.5-fold enhancement of enhanced green fluorescent protein knockdown in cancer cells in comparison to either free siRNA or siRNA-loaded non-acid-degradable lipoplex formulations, respectively.
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: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: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: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: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:Sang-Min Lee and SonBinh T. Nguyen
Macromolecules 2013 Volume 46(Issue 23) pp:9169-9180
Publication Date(Web):November 27, 2013
DOI:10.1021/ma401529w
Since the 1960s, stimuli-responsive polymers have been utilized as functional soft materials for biological applications such as the triggered-release delivery of biologically active cargos. Over the same period, liposomes have been explored as an alternative drug delivery system with potentials to decrease the toxic side effects often associated with conventional small-molecule drugs. However, the lack of drug-release triggers and the instability of bare liposomes often limit their practical applications, causing short circulation time and low therapeutic efficacy. This Perspective highlights recent work in integrating liposomes and stimuli-responsive polymers together to achieve a targetable, triggerable nanoscale platform that fulfills all the characteristics of a near-ideal drug delivery system. Through a drop-in, post-synthesis modification strategy, a network of stimuli-responsive polymers can be integrated onto the surface of liposomes to form polymer-caged nanobins, a multifunctional nanoscale delivery platform that allows for multidrug loading, targeted delivery, triggered drug release, and theranostic capabilities.
Co-reporter:Allison M. Beese, Sourangsu Sarkar, Arun Nair, Mohammad Naraghi, Zhi An, Alexander Moravsky, Raouf O. Loutfy, Markus J. Buehler, SonBinh T. Nguyen, and Horacio D. Espinosa
ACS Nano 2013 Volume 7(Issue 4) pp:3434
Publication Date(Web):April 2, 2013
DOI:10.1021/nn400346r
Polymer composite yarns containing a high loading of double-walled carbon nanotubes (DWNTs) have been developed in which the inherent acrylate-based organic coating on the surface of the DWNT bundles interacts strongly with poly(vinyl alcohol) (PVA) through an extensive hydrogen-bond network. This design takes advantage of a toughening mechanism seen in spider silk and collagen, which contain an abundance of hydrogen bonds that can break and reform, allowing for large deformation while maintaining structural stability. Similar to that observed in natural materials, unfolding of the polymeric matrix at large deformations increases ductility without sacrificing stiffness. As the PVA content in the composite increases, the stiffness and energy to failure of the composite also increases up to an optimal point, beyond which mechanical performance in tension decreases. Molecular dynamics (MD) simulations confirm this trend, showing the dominance of nonproductive hydrogen bonding between PVA molecules at high PVA contents, which lubricates the interface between DWNTs.Keywords: bio-inspired; carbon nanotube; hydrogen-bonding; molecular dynamics; polymer composite; yarn
Co-reporter:Ibrahim Eryazici ; Ilyas Yildirim ; George C. Schatz
Journal of the American Chemical Society 2012 Volume 134(Issue 17) pp:7450-7458
Publication Date(Web):March 19, 2012
DOI:10.1021/ja300322a
Detailed experimental and computational studies revealed the important role that hydrophobic interactions play in the aqueous assembly of rigid small molecule-DNA hybrid (rSMDH) building blocks into nanoscale cage and face-to-face (ff) dimeric structures. In aqueous environments, the hydrophobic surfaces of the organic cores in these nanostructures are minimized by interactions with the core in another rSMDHs, with the bases in the attached DNA strands, and/or with the base pairs in the final assembled structures. In the case that the hydrophobic surfaces of the cores could not be properly isolated in the assembly process, an ill-defined network results instead of dimers, even at low concentration of DNA. In contrast, if ff dimers can be formed with good minimization of the exposed hydrophobic surfaces of the cores, they are highly stable structures with enhanced melting temperatures and cooperative melting behavior.
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:Byungman Kang, Josh W. Kurutz, Kyoung-Tae Youm, Ryan K. Totten, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science 2012 vol. 3(Issue 6) pp:1938-1944
Publication Date(Web):26 Jan 2012
DOI:10.1039/C2SC00950A
Box-like tetrakis(metalloporphyrin) supramolecular assemblies possessing Zn and Al metal sites can catalyze the methanolysis of phosphate triesters with a high rate enhancement, up to 430 times faster than the uncatalyzed reaction. Mechanistic studies suggest that the observed rate enhancement can be attributed to a high local concentration of methoxide ion that operates in concert with a solvophobically driven encapsulation of substrates by the porphyrinic assembly.
Co-reporter:Sai Archana Krovi, Elden P. Swindell, Thomas V. O'Halloran and SonBinh T. Nguyen
Journal of Materials Chemistry A 2012 vol. 22(Issue 48) pp:25463-25470
Publication Date(Web):12 Nov 2012
DOI:10.1039/C2JM35420A
Polymer nanoparticles (PNPs) possessing a high density of drug payload have been successfully stabilized against aggregation in biological buffers after amine modification, which renders these PNPs positively charged. The resulting charge-stabilized PNPs retain their original narrow particle size distributions and well-defined spherical morphologies. This stabilization allows these PNPs to have an improved anti-proliferative effect on MDA-MB-231-Br human breast cancer cells compared to non-functionalized PNPs. As a non-cytotoxic control, similar surface-modified PNPs containing cholesterol in place of doxorubicin did not inhibit cell proliferation, indicating that the induced cytotoxic response was solely due to the doxorubicin release from the PNPs.
Co-reporter:Ryan K. Totten, Patrick Ryan, Byungman Kang, Suk Joong Lee, Linda J. Broadbelt, Randall Q. Snurr, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2012 vol. 48(Issue 35) pp:4178-4180
Publication Date(Web):31 Jan 2012
DOI:10.1039/C2CC17568A
A series of metalloporphyrin dimers were modularly prepared and shown to catalyze the methanolysis of a phosphate triester, yielding rates that are large compared to the rate of the uncatalyzed reaction. Up to 1300-fold rate acceleration can be achieved via a combination of cavity-localized Lewis-acid activation and methoxide-induced methanolysis.
Co-reporter:Yalan Ning ; Amy A. Sarjeant ; Charlotte L. Stern ; Thomas H. Peterson
Inorganic Chemistry 2012 Volume 51(Issue 5) pp:3051-3058
Publication Date(Web):February 22, 2012
DOI:10.1021/ic202430m
Mo0 dinitrogen complexes bearing electron-rich mono- and bidentate phosphines can be synthesized in good yields from inexpensive and readily accessible MoCl5 via a one-step mild reduction with Mg metal. trans-[(N2)2Mo(PMePh2)(PPh(CH2CH2PPh2)2)] can also be obtained via this strategy. However, in the presence of tri- and tetradentate ligands that are sterically restrictive, the analogous reduction leads to either (η6-arene) formation or [Mo(multidentate phosphine)m]n oligomer complexes that have no dinitrogen ligands. One such η6-arene complex, where the Mo0 center is ligated by 1,1,1-tris(diphenylphosphinomethyl)ethane, was isolated and characterized via X-ray crystallography.
Co-reporter:Byungman Kang, Ryan K. Totten, Mitchell H. Weston, Joseph T. Hupp and SonBinh T. Nguyen
Dalton Transactions 2012 vol. 41(Issue 39) pp:12156-12162
Publication Date(Web):06 Aug 2012
DOI:10.1039/C2DT31126G
Covalently linked cyclic metalloporphyrin dimers and tetramers have been demonstrated to be good shape-selective hosts for fullerene guests. The fullerene affinities of these hosts can readily be tuned by modulating the covalent linkage and the metal ions in the porphyrin subunits. A rigid Zn(porphyrin) dimer with conjugated bis(alkynyl) linkers exhibits a high selectivity towards C70 over C60 in toluene (Ka,C70/Ka,C60 = ∼28). For the host structures examined, a synergistic combination of rigidity in the linker and electropositive Al ions gives rise to the strongest binding of C70. In the case of a bisected Zn(porphyrin) tetramer, two well-defined cavities exist; however, due to their comparatively small size, only one C60 can be accommodated. Studies of fullerene binding as a function of metal ion in a porphyrin divider suggest that the right combination of shape and steric match is essential to exploit both van der Waals and local-charge/induced-dipole interactions.
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:Owen C. Compton, Martin Egan, Rupa Kanakaraj, Thomas B. Higgins, and SonBinh T. Nguyen
Journal of Chemical Education 2012 Volume 89(Issue 11) pp:1442-1446
Publication Date(Web):August 22, 2012
DOI:10.1021/ed200478d
Periodic conductivity trends are placed in the scope of lithium-ion batteries, where increases in the ionic radii of salt components affect the conductivity of a poly(ethyleneoxide)-based polymer electrolyte. Numerous electrolytes containing varying concentrations and types of metal salts are prepared and evaluated in either one or two laboratory sessions, requiring cooperation between all students in the classroom. The experiment is suitable for either high school students with a general chemistry background or undergraduate students in introductory general chemistry courses, as a number of fundamental topics can be discussed with this simple, inexpensive, and real-world-oriented project.Keywords: Applications of Chemistry; Conductivity; Electrolytic/Galvanic Cells/Potentials; First-Year Undergraduate/General; Hands-On Learning/Manipulatives; High School/Introductory Chemistry; Inquiry-Based/Discovery Learning; Laboratory Instruction; Periodicity/Periodic Table; Physical Chemistry;
Co-reporter:Bong Jin Hong, Owen C. Compton, Zhi An, Ibrahim Eryazici, and SonBinh T. Nguyen
ACS Nano 2012 Volume 6(Issue 1) pp:63
Publication Date(Web):October 23, 2011
DOI:10.1021/nn202355p
Aqueous dispersions of graphene oxide are inherently unstable in the presence of electrolytes, which screen the electrostatic surface charge on these nanosheets and induce irreversible aggregation. Two complementary strategies, utilizing either electrostatic or steric stabilization, have been developed to enhance the stability of graphene oxide in electrolyte solutions, allowing it to stay dispersed in cell culture media and serum. The electrostatic stabilization approach entails further oxidation of graphene oxide to low C/O ratio (∼1.1) and increases ionic tolerance of these nanosheets. The steric stabilization technique employs an amphiphilic block copolymer that serves as a noncovalently bound surfactant to minimize the aggregate-inducing nanosheet–nanosheet interactions. Both strategies can stabilize graphene oxide nanosheets with large dimensions (>300 nm) in biological media, allowing for an enhancement of >250% in the bioconjugation efficiency of streptavidin in comparison to untreated nanosheets. Notably, both strategies allow the stabilized nanosheets to be readily taken up by cells, demonstrating their excellent performance as potential drug-delivery vehicles.Keywords: biofunctionalization; cellular uptake; delivery vehicle; electrolytic stabilization; graphene oxide; ionic stabilization; Pluronics
Co-reporter:Owen C. Compton, Steven W. Cranford, Karl W. Putz, Zhi An, L. Catherine Brinson, Markus J. Buehler, and SonBinh T. Nguyen
ACS Nano 2012 Volume 6(Issue 3) pp:2008
Publication Date(Web):December 21, 2011
DOI:10.1021/nn202928w
The mechanical properties of pristine graphene oxide paper and paper-like films of polyvinyl alcohol (PVA)-graphene oxide nanocomposite are investigated in a joint experimental–theoretical and computational study. In combination, these studies reveal a delicate relationship between the stiffness of these papers and the water content in their lamellar structures. ReaxFF-based molecular dynamics (MD) simulations elucidate the role of water molecules in modifying the mechanical properties of both pristine and nanocomposite graphene oxide papers, as bridge-forming water molecules between adjacent layers in the paper structure enhance stress transfer by means of a cooperative hydrogen-bonding network. For graphene oxide paper at an optimal concentration of ∼5 wt % water, the degree of cooperative hydrogen bonding within the network comprising adjacent nanosheets and water molecules was found to optimally enhance the modulus of the paper without saturating the gallery space. Introducing PVA chains into the gallery space further enhances the cooperativity of this hydrogen-bonding network, in a manner similar to that found in natural biomaterials, resulting in increased stiffness of the composite. No optimal water concentration could be found for the PVA-graphene oxide nanocomposite papers, as dehydration of these structures continually enhances stiffness until a final water content of ∼7 wt % (additional water cannot be removed from the system even after 12 h of annealing).Keywords: graphene oxide; graphene oxide paper; mechanical properties; molecular dynamics simulations; polymer nanocomposite
Co-reporter:Owen C. Compton, Zhi An, Karl W. Putz, Bong Jin Hong, Brad G. Hauser, L. Catherine Brinson, SonBinh T. Nguyen
Carbon 2012 50(10) pp: 3399-3406
Publication Date(Web):
DOI:10.1016/j.carbon.2012.01.061
Co-reporter: Youn-Sang Bae;Dr. Chang Yeon Lee;Dr. Ki Chul Kim; Omar K. Farha;Dr. Peter Nickias; Joseph T. Hupp; SonBinh T. Nguyen; Rall Q. Snurr
Angewandte Chemie International Edition 2012 Volume 51( Issue 8) pp:1857-1860
Publication Date(Web):
DOI:10.1002/anie.201107534
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:Parminder Kaur, Joseph T. Hupp, and SonBinh T. Nguyen
ACS Catalysis 2011 Volume 1(Issue 7) pp:819
Publication Date(Web):May 25, 2011
DOI:10.1021/cs200131g
Porous organic polymers (POPs), a class of highly cross-linked, amorphous polymers possessing micropores, have recently emerged as a versatile platform for the deployment of catalysts. These materials can be divided into three major classes: POPs that incorporate rigid well-defined homogeneous catalysts as building blocks, POPs that can be modified post-synthesis, and POPs that encapsulate metal particles. This perspective article summarizes the recent developments in POP-based catalysis and outlines the potential of POPs as platforms of heterogeneous catalysts along with some of the challenges.Keywords: conjugated porous polymers; heterogeneous catalysis; hyper-cross-linked polymers; porous organic polymers
Co-reporter:Abraham M. Shultz, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science 2011 vol. 2(Issue 4) pp:686-689
Publication Date(Web):04 Jan 2011
DOI:10.1039/C0SC00339E
The synthesis of a porous organic polymer (POP) containing free-base porphyrin subunits has been accomplished by the condensation of a bis(phthalic acid)porphyrin with tetra(4-aminophenyl)methane. Metallation by post-synthesis modification affords microporous materials incorporating either Fe or Mn(porphyrins) that have been shown to be active catalysts for both olefin epoxidation and alkane hydroxylation.
Co-reporter:Prativa Pandey, Omar K. Farha, Alexander M. Spokoyny, Chad A. Mirkin, Mercouri G. Kanatzidis, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2011 vol. 21(Issue 6) pp:1700-1703
Publication Date(Web):05 Jan 2011
DOI:10.1039/C0JM03483E
A thermally and chemically stable “click-based” porous organic polymer with high surface area was synthesized from two tetrahedral building blocks.
Co-reporter:Abraham M. Shultz ; Omar K. Farha ; Debashis Adhikari ; Amy A. Sarjeant ; Joseph T. Hupp
Inorganic Chemistry 2011 Volume 50(Issue 8) pp:3174-3176
Publication Date(Web):March 7, 2011
DOI:10.1021/ic101952y
From a combination of chiral Mn(salen) struts and the tetratopic ligand tetrakis(4-carboxyphenyl)benzene, a large-pore, noncatenated metal-organic framework (MOF) material, MnSO-MOF, has been synthesized. Following solvent exchange with hydrophobic CHCl3, treatment of MnSO-MOF with aqueous H2O2 allowed for the selective demetalation of Mn(salen) struts at and near the surface of the crystals. The resulting crystals displayed greatly enhanced size-selective catalysis compared to the as-synthesized material. Handling of the mechanically fragile MnSO-MOF crystals was greatly facilitated by activation with supercritical CO2.
Co-reporter:Ibrahim Eryazici, Omar K. Farha, Owen C. Compton, Charlotte Stern, Joseph T. Hupp and SonBinh T. Nguyen
Dalton Transactions 2011 vol. 40(Issue 36) pp:9189-9193
Publication Date(Web):08 Aug 2011
DOI:10.1039/C1DT10671F
A new class of infinite coordination polymers (CP) was synthesized using a tetrahedral tetrakis[4-(4′-phenyl-2,2′:6′,2′′-terpyridine)phenyl]methane ligand as an organic node to direct the three-dimensional growth of the network and MII (M = Zn, Fe, Ni, and Ru) ions as inorganic linkers, an approach that is the opposite of the metal-as-a-node strategy used in the construction of metal–organic frameworks (MOFs). The unusual rod-like morphology of the resulting microporous materials can be tuned viasolvents and reaction conditions. The covalent entrapment of a [Ru(tpy)2]2+ moiety in the skeleton of the 3D-network enables the Ru-CP to exhibit room-temperature luminescence.
Co-reporter:Sang-Min Lee, One-Sun Lee, Thomas V. O’Halloran, George C. Schatz, and SonBinh T. Nguyen
ACS Nano 2011 Volume 5(Issue 5) pp:3961
Publication Date(Web):April 5, 2011
DOI:10.1021/nn200478m
Nanoscale drug delivery platforms can provide an attractive therapeutic strategy for cancer treatments, as they can substantially reduce the adverse side effects associated with toxic small-molecule anticancer agents. For enhanced therapeutic efficacy to be achieved with such platforms, a tumor-specific drug-release trigger is a critical requirement. This article reports the use of a pH-sensitive polymer network that surrounds a nanoscale liposome core to trigger the release of both encapsulated hydrophilic, membrane-impermeable NiII cations and amphipathic, membrane-permeable AsIII anticancer agents under acidic conditions commonly encountered in hypoxic tumor tissues and late endosomes. Computational modeling studies provide clear evidence that the acid-triggered drug-release mechanism for this polymer-caged nanobin (PCN) platform arises from a pH- and temperature-responsive conformation change of the cross-linked polymer cage. As a result, the simultaneous release of both of the active agents in this multicomponent therapeutic enhances the pro-apoptotic activity of AsIII while diminishing its acute toxicity, potentially reducing the undesirable side effects commonly associated with this free drug. The ability to engender acid-triggered release of drugs co-encapsulated inside a liposomal template makes drug delivery using PCN an attractive strategy for triggered drug release.Keywords: arsenic trioxide; drug delivery; liposome; molecular modeling; pH-sensitive release; polymer
Co-reporter:Owen C. Compton, Bonny Jain, Dmitriy A. Dikin, Ali Abouimrane, Khalil Amine, and SonBinh T. Nguyen
ACS Nano 2011 Volume 5(Issue 6) pp:4380
Publication Date(Web):April 7, 2011
DOI:10.1021/nn1030725
Organic dispersions of graphene oxide can be thermally reduced in polar organic solvents under reflux conditions to afford electrically conductive, chemically active reduced graphene oxide (CARGO) with tunable C/O ratios, dependent on the boiling point of the solvent. The reductions are achieved after only 1 h of reflux, and the corresponding C/O ratios do not change upon further thermal treatment. Hydroxyl and carboxyl groups can be removed when the reflux is carried out above 155 °C, while epoxides are removable only when the temperature is higher than 200 °C. The increasing hydrophobic nature of CARGO, as its C/O ratio increases, improves the dispersibility of the nanosheets in a polystyrene matrix, in contrast to the aggregates formed with CARGO having lower C/O ratios. The excellent processability of the obtained CARGO dispersions is demonstrated via free-standing CARGO papers that exhibit tunable electrical conductivity/chemical activity and can be used as lithium-ion battery anodes with enhanced Coulombic efficiency.Keywords: graphene; graphene oxide; lithium-ion battery; surface functionalization; thermal reduction
Co-reporter:Karl W. Putz, Owen C. Compton, Claire Segar, Zhi An, SonBinh T. Nguyen, and L. Catherine Brinson
ACS Nano 2011 Volume 5(Issue 8) pp:6601
Publication Date(Web):July 9, 2011
DOI:10.1021/nn202040c
Three mechanisms are proposed for the assembly of ordered, layered structures of graphene oxide, formed via the vacuum-assisted self-assembly of a dispersion of the two-dimensional nanosheets. These possible mechanisms for ordering at the filter–solution interface range from regular brick-and-mortar-like growth to complete disordered aggregation and compression. Through a series of experiments (thermal gravimetric analysis, UV–vis spectroscopy, and X-ray diffraction) a semi-ordered accumulation mechanism is identified as being dominant during paper fabrication. Additionally, a higher length-scale ordered structure (lamellae) is identified through the examination of water-swelled samples, indicating that further refinements are required to capture the complete formation mechanism. Identification of this mechanism and the resulting higher-order structure it produces provide insight into possibilities for creation of ordered graphene oxide-polymer nanocomposites, as well as the postfabrication modification of single-component graphene oxide papers.Keywords: graphene oxide; hierarchical structure; nanostructures; polymer nanocomposite; self assembly
Co-reporter:Owen C. Compton;Dmitriy A. Dikin;Karl W. Putz;L. Catherine Brinson
Advanced Materials 2010 Volume 22( Issue 8) pp:892-896
Publication Date(Web):
DOI:10.1002/adma.200902069
Co-reporter:Owen C. Compton;Soyoung Kim;Cynthia Pierre;John M. Torkelson
Advanced Materials 2010 Volume 22( Issue 42) pp:4759-4763
Publication Date(Web):
DOI:10.1002/adma.201000960
Co-reporter:Sang-Min Lee ; Thomas V. O’Halloran
Journal of the American Chemical Society 2010 Volume 132(Issue 48) pp:17130-17138
Publication Date(Web):November 15, 2010
DOI:10.1021/ja107333g
Multicomponent chemotherapy has increasingly become a strategy of great importance in clinical cancer treatments. However, this type of chemotherapy has not been demonstrated in nanoscale delivery vehicles where two cytotoxic agents can be packaged together, potentially leading to synergistic drug activities. Herein, we present the codelivery of doxorubicin and cisplatin via a single polymer-caged nanobin (PCN) and show that copackaging can yield strong synergy in the efficacy of these agents. Such a PCN comprises a doxorubicin-encapsulated liposomal core protected by a pH-responsive cisplatin prodrug-loaded polymer shell with tunable drug ratios and surface charge potentials. This dual-agent Pt-PCNDXR formulation dramatically enhances the overall cytotoxicity of each drug against cancer cells at reduced doses and exhibits higher synergy than combinations of either the free drugs or separately nano-packaged drugs. These results clearly indicate that the polymer-caged nanobin platform can offer new means for building synergy into combination chemotherapy regimens.
Co-reporter:Ibrahim Eryazici ; Tatiana R. Prytkova ; George C. Schatz
Journal of the American Chemical Society 2010 Volume 132(Issue 48) pp:17068-17070
Publication Date(Web):November 12, 2010
DOI:10.1021/ja107232x
Small molecule−DNA hybrids with only two parallel DNA duplexes (rSMDH2) displayed sharper melting profiles compared to unmodified DNA duplexes, consistent with predictions from neighboring-duplex theory. Using adjusted thermodynamic parameters obtained from a coarse-grain dynamic simulation, the experimental data fit well to an analytical model.
Co-reporter:Karl W. Putz;Owen C. Compton;Marc J. Palmeri;L. Catherine Brinson
Advanced Functional Materials 2010 Volume 20( Issue 19) pp:3322-3329
Publication Date(Web):
DOI:10.1002/adfm.201000723
Abstract
Highly ordered, homogeneous polymer nanocomposites of layered graphene oxide are prepared using a vacuum-assisted self-assembly (VASA) technique. In VASA, all components (nanofiller and polymer) are pre-mixed prior to assembly under a flow, making it compatible with either hydrophilic poly(vinyl alcohol) (PVA) or hydrophobic poly(methyl methacrylate) (PMMA) for the preparation of composites with over 50 wt% filler. This process is complimentary to layer-by-layer assembly, where the assembling components are required to interact strongly (e.g., via Coulombic attraction). The nanosheets within the VASA-assembled composites exhibit a high degree of order with tunable intersheet spacing, depending on the polymer content. Graphene oxide–PVA nanocomposites, prepared from water, exhibit greatly improved modulus values in comparison to films of either pure PVA or pure graphene oxide. Modulus values for graphene oxide–PMMA nanocomposites, prepared from dimethylformamide, are intermediate to those of the pure components. The differences in structure, modulus, and strength can be attributed to the gallery composition, specifically the hydrogen bonding ability of the intercalating species
Co-reporter:Sasha Stankovich, Dmitriy A. Dikin, Owen C. Compton, Geoffrey H. B. Dommett, Rodney S. Ruoff and SonBinh T. Nguyen
Chemistry of Materials 2010 Volume 22(Issue 14) pp:4153
Publication Date(Web):June 22, 2010
DOI:10.1021/cm100454g
Graphene oxide paper can be systematically modified with alkylamines in both solution- and vapor-phase, with the latter process being significantly slower. After removal of physisorbed amine, the increases in gallery spacing, physical thickness, and mass of amine-modified papers can be directly correlated to the length of the intercalated alkyl chain. While the tensile strength of the modified papers slightly decreases with increasing amine lengths, their “effective graphene oxide moduli” were essentially unchanged, suggesting that graphene oxide is the sole contributor to the stiffness of amine-modified papers.
Co-reporter:Prativa Pandey, Alexandros P. Katsoulidis, Ibrahim Eryazici, Yuyang Wu, Mercouri G. Kanatzidis and SonBinh T. Nguyen
Chemistry of Materials 2010 Volume 22(Issue 17) pp:4974
Publication Date(Web):August 3, 2010
DOI:10.1021/cm101157w
Imine-linked microporous polymer organic frameworks (POFs) were synthesized via Schiff base condensation between 1,3,5-triformylbenzene and several readily available diamine monomers. Our facile, one-pot approach results in quantitative yields of POFs with the flexibility to incorporate several functional groups in their pores for tuning the interaction of their surface with different guest molecules. Synthesized POFs exhibit high specific surface areas (up to 1500 m2 g−1) as well as high isosteric heats of H2 adsorption (up to 8.2 kJ mol−1).
Co-reporter:Sai Archana Krovi, DeeDee Smith and SonBinh T. Nguyen
Chemical Communications 2010 vol. 46(Issue 29) pp:5277-5279
Publication Date(Web):23 Jun 2010
DOI:10.1039/C0CC00232A
The versatility of copper-catalyzed alkyne–azide coupling (CuAAC) in functionalizing drug-loaded polymer nanoparticles is demonstrated via the modification of surfaces of acetylene-functionalized PNPs with folate, biotin, and gold nanoparticles.
Co-reporter:Ali Abouimrane, Owen C. Compton, Khalil Amine and SonBinh T. Nguyen
The Journal of Physical Chemistry C 2010 Volume 114(Issue 29) pp:12800-12804
Publication Date(Web):June 30, 2010
DOI:10.1021/jp103704y
Non-annealed graphene paper, prepared via reduction of prefabricated graphene oxide paper with hydrazine hydrate, was employed as the sole component of a binder-free lithium-ion battery anode, circumventing the polymer binders and other additives required for the fabrication of conventional electrodes. The binder-free anode fabricated from this non-annealed paper possessed excellent cyclability, while exhibiting a voltage versus capacity profile similar to that of a polymer-bound graphene powder anode. Kinetic barriers may exist for Li ion diffusion through the layered paper structure as decreasing the current rate from 50 to 10 mA·g−1 increased the reversible capacity by over 150%.
Co-reporter:Jui-Ching Lin, Jun-Hyun Kim, Joshua A. Kellar, Mark C. Hersam, SonBinh T. Nguyen and Michael J. Bedzyk
Langmuir 2010 Volume 26(Issue 6) pp:3771-3773
Publication Date(Web):February 17, 2010
DOI:10.1021/la903578r
A novel step-by-step method employing microwave-assisted Sonogashira coupling is developed to grow fully conjugated organosilicon structures. As the first case study, p-(4-bromophenyl)acetylene is covalently conjugated to a p-(4-iodophenyl)acetylene-derived monolayer on a Si(111) surface. By bridging the two aromatic rings with C≡C, the pregrown monolayer is structurally extended outward from the Si surface, forming a fully conjugated (p-(4-bromophenylethynyl)phenyl)vinylene film. The film growth process, which reaches 90% yield after 2 h, is characterized thoroughly at each step by using X-ray reflectivity (XRR), X-ray standing waves (XSW), and X-ray fluorescence (XRF). The high yield and short reaction time offered by microwave-assisted surface Sonogashira coupling chemistry make it a promising strategy for functionalizing Si surfaces.
Co-reporter:Sang-Min Lee, Richard W. Ahn, Feng Chen, Angela J. Fought, Thomas V. O’Halloran, Vincent L. Cryns, and SonBinh T. Nguyen
ACS Nano 2010 Volume 4(Issue 9) pp:4971
Publication Date(Web):August 25, 2010
DOI:10.1021/nn100560p
A series of doxorubicin-loaded polymer-caged nanobins (PCNDXR) were evaluated in vivo in a murine MDA-MB-231 xenograft model of triple-negative breast cancer. The cross-linked polymer cage in PCNDXR offers protection for the drug payload while serving as a pH-responsive trigger that enhances drug release in the acidic environments commonly seen in solid tumors and endosomes. Varying the degree of cross-linking in the polymer cage allows the surface potential of PCNDXR, and thus the in vivo circulation lifetime of the nanocarriers, to be tuned in a facile fashion. Given these design advantages, the present study provides the first in vivo evidence that PCNDXR can effectively inhibit tumor growth in a murine model of breast cancer. Importantly, PCNDXR was well-tolerated by mice, and drug encapsulation attenuated the toxicity of free doxorubicin. Taken together, this study demonstrates the potential utility of the PCN platform in cancer therapy.Keywords: breast cancer; in vivo drug delivery; liposomes; pH-responsive release; polymers
Co-reporter:Dr. Sang-Min Lee;Dr. Ying Song;Dr. Bong Jin Hong;Dr. Keith W. MacRenaris;Daniel J. Mastarone; Thomas V. O'Halloran; Thomas J. Meade; SonBinh T. Nguyen
Angewandte Chemie International Edition 2010 Volume 49( Issue 51) pp:9960-9964
Publication Date(Web):
DOI:10.1002/anie.201004867
Co-reporter:Sang-Min Lee ; Haimei Chen ; Thomas V. O’Halloran
Journal of the American Chemical Society 2009 Volume 131(Issue 26) pp:9311-9320
Publication Date(Web):June 15, 2009
DOI:10.1021/ja9017336
Modularly clickable polymer-caged nanobins (PCNs) were prepared from liposome templates using a drop-in cholesterol-modified poly(acrylic acid) reagent followed by cross-linking with alkyne-functionalized diamine linker that allows for the conjugation of azide-modified targeting ligands via click ligation. These PCNs possess pH-responsive characteristics that can be used to trigger the release of encapsulated doxorubicin (DXR) payload inside the liposomal core under mild acidic conditions. After click-conjugation with azide-modified folate as an active targeting ligand, the resulting folate-conjugated, DXR-loaded PCNs (f-PCNDXR) demonstrated enhanced potency to folate receptor (FR)-positive tumor cells such as KB and OvCa432 over FR-negative MCF7 cells. f-PCNDXR can readily discriminate FR-positive tumor cells as a function of the level of cellular FR-expression, showing different degrees of potentiation in each cell. With both targeting functionalities and pH-sensitive drug-releasing triggers, f-PCNDXR was fifty-times more potent than the untargeted agent toward cancer cells that overexpress the folate target receptors.
Co-reporter:Tendai Gadzikwa ; Omar K. Farha ; Christos D. Malliakas ; Mercouri G. Kanatzidis ; Joseph T. Hupp
Journal of the American Chemical Society 2009 Volume 131(Issue 38) pp:13613-13615
Publication Date(Web):September 9, 2009
DOI:10.1021/ja904189d
A noncatenated, Zn-based metal−organic framework (MOF) material bearing silyl-protected acetylenes was constructed and postsynthetically modified using “click” chemistry. Using a solvent-based, selective deprotection strategy, two different organic azides were “clicked” onto the MOF crystals, resulting in a porous material whose internal and external surfaces are differently functionalized.
Co-reporter:DeeDee Smith, Sandra H. Clark, Paul A. Bertin, Bernard L. Mirkin and SonBinh T. Nguyen
Journal of Materials Chemistry A 2009 vol. 19(Issue 15) pp:2159-2165
Publication Date(Web):16 Feb 2009
DOI:10.1039/B817511J
A new type of polymer nanoparticle (PNP) containing a high density of covalently linked doxorubicin, attached via a non-cleavable amine linkage (amine-linked Dox-PNP) was prepared. Together with a previously reported cleavable carbamate-linked Dox-PNP, this new amine-linked Dox-PNP was subsequently evaluated against free doxorubicin for its cytotoxicity and inhibitory effects on SKNSH wild-type and SKrDOX6 doxorubicin-resistant human neuroblastoma cell lines. Analogous cholesterol-containing PNPs (Chol-PNPs) and indomethacin-containing PNPs (IND-PNPs) were also synthesized and used as the non-cytotoxic controls. While neither cell line was affected by Chol-PNPs or IND-PNPs, SKrDOX6 doxorubicin-resistant cells exhibited similar cytotoxic responses to free doxorubicin and both amine- and carbamate-linked Dox-PNPs, suggesting that doxorubicin or the doxorubicin-containing polymer must be the active agent in the latter case. SKNSH wild-type cells also responded to both Dox-PNPs, albeit at a higher apparent concentration than free doxorubicin alone. The growth of SKNSH wild-type cells was significantly inhibited upon incubation with carbamate-linked Dox-PNPs, as with free doxorubicin, over a 7 day period. In comparison to free doxorubicin, carbamate-linked Dox-PNPs produced a longer (72 h) period of initial inhibition in SKrDOX6 doxorubicin-resistant cells.
Co-reporter:Byungman Kang, Aaron W. Miller, Sandra Goyal and SonBinh T. Nguyen
Chemical Communications 2009 (Issue 26) pp:3928-3930
Publication Date(Web):26 May 2009
DOI:10.1039/B902647A
Sc(OTf)3 effectively catalyzes the condensation of 2-alkyl-N-tosylaziridine with a wide variety of aldehydes and ketones, producing 5-alkyl-1,3-oxazolidines in good yields and excellent regioselectivity at catalyst loadings as low as 1 mol%.
Co-reporter:Tendai Gadzikwa, Omar K. Farha, Karen L. Mulfort, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2009 (Issue 25) pp:3720-3722
Publication Date(Web):26 May 2009
DOI:10.1039/B823392F
A Zn-based, mixed-ligand (pillared paddlewheel), metal–organic framework (MOF) has been covalently and quantitatively decorated with free carboxylic acids to demonstrate the utility of covalent post-synthesis modification in the construction of otherwise inaccessible carboxy-functionalized MOFs.
Co-reporter:Joshua A. Kellar, Jui-Ching Lin, Jun-Hyun Kim, Nathan L. Yoder, Kirk H. Bevan, Grace Y. Stokes, Franz M. Geiger, SonBinh T. Nguyen, Michael J. Bedzyk and Mark C. Hersam
The Journal of Physical Chemistry C 2009 Volume 113(Issue 7) pp:2919-2927
Publication Date(Web):2017-2-22
DOI:10.1021/jp8100249
Highly conjugated molecules bound to silicon are promising candidates for organosilicon electronic devices and sensors. In this study, 1-bromo-4-ethynylbenzene was synthesized and reacted with a hydrogen-passivated Si(111) surface via ultraviolet irradiation. Through an array of characterization and modeling tools, the binding configuration and morphology of the reacted molecule were thoroughly analyzed. Atomic force microscopy confirmed an atomically flat surface morphology following reaction, while X-ray photoelectron spectroscopy verified reaction to the surface via the terminal alkyne moiety. In addition, synchrotron X-ray characterization, including X-ray reflectivity, X-ray fluorescence, and X-ray standing wave measurements, enabled sub-angstrom determination of the position of the bromine atom with respect to the silicon lattice. This structural characterization was quantitatively compared with density functional theory (DFT) calculations, thus enabling the π-conjugation of the terminal carbon atoms to be deduced. The X-ray and DFT results were additionally corroborated with the vibrational spectrum of the organic adlayer, which was measured with sum frequency generation. Overall, these results illustrate that the terminal carbon atoms in 1-bromo-4-ethynylbenzene adlayers on Si(111) retain π-conjugation, thus revealing alkyne molecules as promising candidates for organosilicon electronics and sensing.
Co-reporter:Suk Joong Lee, Rebecca A. Jensen, Christos D. Malliakas, Mercouri G. Kanatzidis, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2008 vol. 18(Issue 31) pp:3640-3642
Publication Date(Web):08 Jul 2008
DOI:10.1039/B804629H
A highly efficient porphyrin synthesis facilitates a systematic investigation of the effects that secondary substituents have on the physical properties, crystal structures, and nanoparticle morphologies of amphiphilic (porphyrin)Sn(OH)2.
Co-reporter:Tendai Gadzikwa, Guang Lu, Charlotte L. Stern, Scott R. Wilson, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2008 (Issue 43) pp:5493-5495
Publication Date(Web):08 Oct 2008
DOI:10.1039/B805101A
A Zn-cornered, mixed-ligand, metal–organic framework (MOF) bearing TMS-protected acetylenes has been constructed and its surface decorated with organic molecules via‘click chemistry’, in a demonstration of selective post-synthesis functionalization.
Co-reporter:Tendai Gadzikwa, Bi-Shun Zeng, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2008 (Issue 31) pp:3672-3674
Publication Date(Web):30 Jun 2008
DOI:10.1039/B714160B
A series of 4,4′-ethynylenedibenzoic acids were synthesized and used in the construction of Zn-based, mixed-ligand metal–organic frameworks; through variation of functionality in the 3- and 3′-positions of these linkers, a collection of MOFs with differing connectivities and varying levels of interpenetration was obtained.
Co-reporter:Kyoung-Tae Youm, SonBinh T. Nguyen and Joseph T. Hupp
Chemical Communications 2008 (Issue 29) pp:3375-3377
Publication Date(Web):27 Jun 2008
DOI:10.1039/B800063H
Hollow, hexa-porphyrin prisms of two sizes were template-assembled and covalently locked, via cross-olefin metathesis, into permanent, torsionally rigid structures whose active sites (metal sites) can be both accessed and altered in a facile manner.
Co-reporter:Christopher G. Oliveri ; SonBinh T. Nguyen ;Chad A. Mirkin
Inorganic Chemistry 2008 Volume 47(Issue 7) pp:2755-2763
Publication Date(Web):February 13, 2008
DOI:10.1021/ic702150y
The synthesis of new hemilabile phosphine ligands and their reaction with [Rh(COE)2Cl]2 to form dissymmetric heteroligated tweezer complexes using a halide-induced ligand rearrangement reaction are reported. These complexes can undergo reactions with small-molecule ligands and elemental anions quantitatively in situ, which serve to regulate the porphyrin−porphyrin distances and interactions within the assembly.
Co-reporter:Sungjin Park, Kyoung-Seok Lee, Gulay Bozoklu, Weiwei Cai, SonBinh T. Nguyen and Rodney S. Ruoff
ACS Nano 2008 Volume 2(Issue 3) pp:572
Publication Date(Web):March 6, 2008
DOI:10.1021/nn700349a
Significant enhancement in mechanical stiffness (10–200%) and fracture strength (∼50%) of graphene oxide paper, a novel paperlike material made from individual graphene oxide sheets, can be achieved upon modification with a small amount (less than 1 wt %) of Mg2+ and Ca2+. These results can be readily rationalized in terms of the chemical interactions between the functional groups of the graphene oxide sheets and the divalent metals ions. While oxygen functional groups on the basal planes of the sheets and the carboxylate groups on the edges can both bond to Mg2+ and Ca2+, the main contribution to mechanical enhancement of the paper comes from the latter.Keywords: cross-linking; divalent ion; graphene oxide; graphene oxide paper; graphite; mechanical property;
Co-reporter:Sasha Stankovich, Dmitriy A. Dikin, Richard D. Piner, Kevin A. Kohlhaas, Alfred Kleinhammes, Yuanyuan Jia, Yue Wu, SonBinh T. Nguyen, Rodney S. Ruoff
Carbon 2007 Volume 45(Issue 7) pp:1558-1565
Publication Date(Web):June 2007
DOI:10.1016/j.carbon.2007.02.034
Reduction of a colloidal suspension of exfoliated graphene oxide sheets in water with hydrazine hydrate results in their aggregation and subsequent formation of a high-surface-area carbon material which consists of thin graphene-based sheets. The reduced material was characterized by elemental analysis, thermo-gravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, NMR spectroscopy, Raman spectroscopy, and by electrical conductivity measurements.
Co-reporter:So-Hye Cho;Tendai Gadzikwa;Mitra Afshari;Joseph T. Hupp
European Journal of Inorganic Chemistry 2007 Volume 2007(Issue 31) pp:
Publication Date(Web):26 SEP 2007
DOI:10.1002/ejic.200700302
The formation of coordination polymers by the reaction of [bis(catechol)salen]MnIII with several di- and trivalent metal ions is reported. These polymers are insoluble in a wide range of organic solvents and water but can be dissolved upon addition of excess pyrocatechol. They function as enantioselective heterogeneous epoxidation catalysts and exhibit catalytic activity comparable to that of the homogeneous[bis(catechol)salen]MnIII building block alone when used for the enantioselective epoxidation of 2,2-dimethyl-2H-chromene. After catalysis, catalyst isolation from the reaction mixture can be readily achieved by centrifugation and decantation. Under practical oxidant concentrations, the catalyst can be recycled up to ten times with little loss of activity and no loss of enantioselectivity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Co-reporter:Sasha Stankovich, Richard D. Piner, Xinqi Chen, Nianqiang Wu, SonBinh T. Nguyen and Rodney S. Ruoff
Journal of Materials Chemistry A 2006 vol. 16(Issue 2) pp:155-158
Publication Date(Web):21 Nov 2005
DOI:10.1039/B512799H
For the first time, stable aqueous dispersions of polymer-coated graphitic nanoplatelets can be prepared via an exfoliation/in-situ reduction of graphite oxide in the presence of poly(sodium 4-styrenesulfonate).
Co-reporter:So-Hye Cho, Baoqing Ma, SonBinh T. Nguyen, Joseph T. Hupp and Thomas E. Albrecht-Schmitt
Chemical Communications 2006 (Issue 24) pp:2563-2565
Publication Date(Web):23 May 2006
DOI:10.1039/B600408C
A new microporous metal–organic framework compound featuring chiral (salen)Mn struts is highly effective as an asymmetric catalyst for olefin epoxidation, yielding enantiomeric excesses that rival those of the free molecular analogue. Framework confinement of the manganese salen entity enhances catalyst stability, imparts substrate size selectivity, and permits catalyst separation and reuse.
Co-reporter:Sasha Stankovich, Richard D. Piner, SonBinh T. Nguyen, Rodney S. Ruoff
Carbon 2006 Volume 44(Issue 15) pp:3342-3347
Publication Date(Web):December 2006
DOI:10.1016/j.carbon.2006.06.004
A number of functionalized graphite oxides were prepared by treatment of graphite oxide (GO) with organic isocyanates. These isocyanate-treated GOs (iGOs) can then be exfoliated into functionalized graphene oxide nanoplatelets that can form a stable dispersion in polar aprotic solvents. Characterization of iGOs by FT-IR spectroscopy and elemental analysis suggested that the isocyanate treatment results in the functionalization of the carboxyl and hydroxyl groups in GO via formation of amides and carbamate esters, respectively. The degree of GO functionalization can be controlled via either the reactivity of the isocyanate or the reaction time. When used with functionalized isocyanates, the described methodology allows for the elaboration of graphene oxide nanoplatelets with different surface functional groups.
Co-reporter:Sasha Stankovich,
Dmitriy A. Dikin,
Geoffrey H. B. Dommett,
Kevin M. Kohlhaas,
Eric J. Zimney,
Eric A. Stach,
Richard D. Piner,
SonBinh T. Nguyen
and
Rodney S. Ruoff
Nature 2006 442(7100) pp:282
Publication Date(Web):
DOI:10.1038/nature04969
Co-reporter:So-Hye Cho, Nolan D. Walther, SonBinh T. Nguyen and Joseph T. Hupp
Chemical Communications 2005 (Issue 42) pp:5331-5333
Publication Date(Web):26 Sep 2005
DOI:10.1039/B507541F
Catechol-functionalized (salen)Mn complexes can be supported on mesoporous anodized aluminium oxide disks to yield catalytic membranes that are highly active in the enantioselective epoxidation of olefins when being deployed in a forced-through-flow reactor.
Co-reporter:Paul A. Bertin, DeeDee Smith and SonBinh T. Nguyen
Chemical Communications 2005 (Issue 30) pp:3793-3795
Publication Date(Web):04 Jul 2005
DOI:10.1039/B504643B
High-density doxorubicin-conjugated polymeric nanoparticles are prepared via ring-opening metathesis polymerization and sustained release of nearly 50% of the anticancer agent is observed after 24 h in mildly acidic aqueous solution.
Co-reporter:Jason A. Miller Dr.;Bradley A. Gross;Michael A. Zhuravel Dr.;Wiechang Jin Dr.
Angewandte Chemie 2005 Volume 117(Issue 25) pp:
Publication Date(Web):18 MAY 2005
DOI:10.1002/ange.200460887
„Chirale“ Veredelung: Ein effizientes Verfahren wird zur Entwicklung neuer (Salen)ruthenium(II)-Katalysatoren für die asymmetrische Cyclopropanierung von Olefinen genutzt. Grundlage ist die Verwendung von chiralen Liganden, die billige und einfach zugängliche achirale (Salen)ruthenium(II)-Katalysatoren in chirale Komplexe überführen (siehe Schema; EDA=Ethyldiazoacetat). Die Methode ist zum Parallelscreening geeignet und weist große Vorteile gegenüber herkömmlichen Verfahren der Katalysatorentwicklung auf.
Co-reporter:Jason A. Miller Dr.;Bradley A. Gross;Michael A. Zhuravel Dr.;Wiechang Jin Dr.
Angewandte Chemie International Edition 2005 Volume 44(Issue 25) pp:
Publication Date(Web):18 MAY 2005
DOI:10.1002/anie.200460887
An efficient and facile method is used to develop new (salen)ruthenium(II) catalysts for the asymmetric cyclopropanation of olefins, in which a chiral additive induces asymmetry in inexpensive and readily synthesized achiral (salen)ruthenium(II) catalysts (see scheme; EDA=ethyl diazoacetate). This approach is amenable to parallel-screening optimization and has great potential advantages over traditional catalyst development and synthetic methods.
Co-reporter:Christopher R. Graves, E. Joseph Campbell, SonBinh T. Nguyen
Tetrahedron: Asymmetry 2005 Volume 16(Issue 21) pp:3460-3468
Publication Date(Web):31 October 2005
DOI:10.1016/j.tetasy.2005.08.058
The development of aluminum-based catalysts for the asymmetric Meerwein–Schmidt–Ponndorf–Verley–Oppenauer (MSPVO) reduction/oxidation systems is reviewed with an emphasis on the mechanistic understanding of the origin for activity and selectivity in monometallic catalysts.
Co-reporter:Robert L. Paddock and SonBinh T. Nguyen
Chemical Communications 2004 (Issue 14) pp:1622-1623
Publication Date(Web):15 Jun 2004
DOI:10.1039/B401543F
A catalyst system comprised of a CoIII(salen) complex and a Lewis base is investigated for the reaction of CO2 and a variety of epoxides to form cyclic carbonates. Application of this catalyst system in the kinetic resolution of propylene oxide is also discussed.
Co-reporter:Abraham M. Shultz ; Amy A. Sarjeant ; Omar K. Farha ; Joseph T. Hupp
Journal of the American Chemical Society () pp:
Publication Date(Web):July 19, 2011
DOI:10.1021/ja204820d
A series of metallosalen-based metal–organic frameworks (MOFs) have been prepared by the post-synthesis modification of MnIIISO-MOF, a Mn3+(salen)-based MOF. Treatment of MnIIISO-MOF with H2O2 effects the removal of the Mn3+ ions from the salen struts, which can then be remetalated with a variety of metal precursors to form isostructural MSO-MOF materials. The presence of the new metallosalen struts in MSO-MOF was fully confirmed by ICP-OES, MALDI–TOF MS, PXRD, and TGA. Furthermore, the remetalated MnIISO-MOF material displays similar catalytic activity and porosity to the parent MOF.
Co-reporter:Chang Yeon Lee ; Youn-Sang Bae ; Nak Cheon Jeong ; Omar K. Farha ; Amy A. Sarjeant ; Charlotte L. Stern ; Peter Nickias ; Randall Q. Snurr ; Joseph T. Hupp
Journal of the American Chemical Society () pp:
Publication Date(Web):March 18, 2011
DOI:10.1021/ja200553m
A series of isostructural, noncatenated, zinc-pillared-paddlewheel metal−organic framework materials has been synthesized from 1,2,4,5-tetrakis(carboxyphenyl)benzene and trans-1,2-dipyridylethene struts. Substantial kinetic selectivity in the adsorption of propene over propane can be observed, depending on the pore apertures and the rectangular-plate morphology of the crystals.
Co-reporter:DeeDee Smith, Sandra H. Clark, Paul A. Bertin, Bernard L. Mirkin and SonBinh T. Nguyen
Journal of Materials Chemistry A 2009 - vol. 19(Issue 15) pp:NaN2165-2165
Publication Date(Web):2009/02/16
DOI:10.1039/B817511J
A new type of polymer nanoparticle (PNP) containing a high density of covalently linked doxorubicin, attached via a non-cleavable amine linkage (amine-linked Dox-PNP) was prepared. Together with a previously reported cleavable carbamate-linked Dox-PNP, this new amine-linked Dox-PNP was subsequently evaluated against free doxorubicin for its cytotoxicity and inhibitory effects on SKNSH wild-type and SKrDOX6 doxorubicin-resistant human neuroblastoma cell lines. Analogous cholesterol-containing PNPs (Chol-PNPs) and indomethacin-containing PNPs (IND-PNPs) were also synthesized and used as the non-cytotoxic controls. While neither cell line was affected by Chol-PNPs or IND-PNPs, SKrDOX6 doxorubicin-resistant cells exhibited similar cytotoxic responses to free doxorubicin and both amine- and carbamate-linked Dox-PNPs, suggesting that doxorubicin or the doxorubicin-containing polymer must be the active agent in the latter case. SKNSH wild-type cells also responded to both Dox-PNPs, albeit at a higher apparent concentration than free doxorubicin alone. The growth of SKNSH wild-type cells was significantly inhibited upon incubation with carbamate-linked Dox-PNPs, as with free doxorubicin, over a 7 day period. In comparison to free doxorubicin, carbamate-linked Dox-PNPs produced a longer (72 h) period of initial inhibition in SKrDOX6 doxorubicin-resistant cells.
Co-reporter:Sai Archana Krovi, Elden P. Swindell, Thomas V. O'Halloran and SonBinh T. Nguyen
Journal of Materials Chemistry A 2012 - vol. 22(Issue 48) pp:NaN25470-25470
Publication Date(Web):2012/11/12
DOI:10.1039/C2JM35420A
Polymer nanoparticles (PNPs) possessing a high density of drug payload have been successfully stabilized against aggregation in biological buffers after amine modification, which renders these PNPs positively charged. The resulting charge-stabilized PNPs retain their original narrow particle size distributions and well-defined spherical morphologies. This stabilization allows these PNPs to have an improved anti-proliferative effect on MDA-MB-231-Br human breast cancer cells compared to non-functionalized PNPs. As a non-cytotoxic control, similar surface-modified PNPs containing cholesterol in place of doxorubicin did not inhibit cell proliferation, indicating that the induced cytotoxic response was solely due to the doxorubicin release from the PNPs.
Co-reporter:Prativa Pandey, Omar K. Farha, Alexander M. Spokoyny, Chad A. Mirkin, Mercouri G. Kanatzidis, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2011 - vol. 21(Issue 6) pp:NaN1703-1703
Publication Date(Web):2011/01/05
DOI:10.1039/C0JM03483E
A thermally and chemically stable “click-based” porous organic polymer with high surface area was synthesized from two tetrahedral building blocks.
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:Byungman Kang, Ryan K. Totten, Mitchell H. Weston, Joseph T. Hupp and SonBinh T. Nguyen
Dalton Transactions 2012 - vol. 41(Issue 39) pp:NaN12162-12162
Publication Date(Web):2012/08/06
DOI:10.1039/C2DT31126G
Covalently linked cyclic metalloporphyrin dimers and tetramers have been demonstrated to be good shape-selective hosts for fullerene guests. The fullerene affinities of these hosts can readily be tuned by modulating the covalent linkage and the metal ions in the porphyrin subunits. A rigid Zn(porphyrin) dimer with conjugated bis(alkynyl) linkers exhibits a high selectivity towards C70 over C60 in toluene (Ka,C70/Ka,C60 = ∼28). For the host structures examined, a synergistic combination of rigidity in the linker and electropositive Al ions gives rise to the strongest binding of C70. In the case of a bisected Zn(porphyrin) tetramer, two well-defined cavities exist; however, due to their comparatively small size, only one C60 can be accommodated. Studies of fullerene binding as a function of metal ion in a porphyrin divider suggest that the right combination of shape and steric match is essential to exploit both van der Waals and local-charge/induced-dipole interactions.
Co-reporter:Abraham M. Shultz, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science (2010-Present) 2011 - vol. 2(Issue 4) pp:NaN689-689
Publication Date(Web):2011/01/04
DOI:10.1039/C0SC00339E
The synthesis of a porous organic polymer (POP) containing free-base porphyrin subunits has been accomplished by the condensation of a bis(phthalic acid)porphyrin with tetra(4-aminophenyl)methane. Metallation by post-synthesis modification affords microporous materials incorporating either Fe or Mn(porphyrins) that have been shown to be active catalysts for both olefin epoxidation and alkane hydroxylation.
Co-reporter:Byungman Kang, Josh W. Kurutz, Kyoung-Tae Youm, Ryan K. Totten, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Science (2010-Present) 2012 - vol. 3(Issue 6) pp:NaN1944-1944
Publication Date(Web):2012/01/26
DOI:10.1039/C2SC00950A
Box-like tetrakis(metalloporphyrin) supramolecular assemblies possessing Zn and Al metal sites can catalyze the methanolysis of phosphate triesters with a high rate enhancement, up to 430 times faster than the uncatalyzed reaction. Mechanistic studies suggest that the observed rate enhancement can be attributed to a high local concentration of methoxide ion that operates in concert with a solvophobically driven encapsulation of substrates by the porphyrinic assembly.
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:Tendai Gadzikwa, Guang Lu, Charlotte L. Stern, Scott R. Wilson, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2008(Issue 43) pp:NaN5495-5495
Publication Date(Web):2008/10/08
DOI:10.1039/B805101A
A Zn-cornered, mixed-ligand, metal–organic framework (MOF) bearing TMS-protected acetylenes has been constructed and its surface decorated with organic molecules via‘click chemistry’, in a demonstration of selective post-synthesis functionalization.
Co-reporter:Sanjiban Chakraborty, Yamil J. Colón, Randall Q. Snurr and SonBinh T. Nguyen
Chemical Science (2010-Present) 2015 - vol. 6(Issue 1) pp:NaN389-389
Publication Date(Web):2014/09/16
DOI:10.1039/C4SC02502D
Porous organic polymers (POPs) possessing meso- and micropores can be obtained by carrying out the polymerization inside a mesoporous silica aerogel template and then removing the template after polymerization. The total pore volume (tpv) and specific surface area (ssa) can be greatly enhanced by modifying the template (up to 210% increase for tpv and 73% for ssa) as well as by supercritical processing of the POPs (up to an additional 142% increase for tpv and an additional 32% for ssa) to include larger mesopores. The broad range of pores allows for faster transport of molecules through the hierarchically porous POPs, resulting in increased diffusion rates and faster gas uptake compared to POPs with only micropores.
Co-reporter:Tendai Gadzikwa, Bi-Shun Zeng, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2008(Issue 31) pp:NaN3674-3674
Publication Date(Web):2008/06/30
DOI:10.1039/B714160B
A series of 4,4′-ethynylenedibenzoic acids were synthesized and used in the construction of Zn-based, mixed-ligand metal–organic frameworks; through variation of functionality in the 3- and 3′-positions of these linkers, a collection of MOFs with differing connectivities and varying levels of interpenetration was obtained.
Co-reporter:Ryan K. Totten, Patrick Ryan, Byungman Kang, Suk Joong Lee, Linda J. Broadbelt, Randall Q. Snurr, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2012 - vol. 48(Issue 35) pp:NaN4180-4180
Publication Date(Web):2012/01/31
DOI:10.1039/C2CC17568A
A series of metalloporphyrin dimers were modularly prepared and shown to catalyze the methanolysis of a phosphate triester, yielding rates that are large compared to the rate of the uncatalyzed reaction. Up to 1300-fold rate acceleration can be achieved via a combination of cavity-localized Lewis-acid activation and methoxide-induced methanolysis.
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:Huong Giang T. Nguyen, Lily Mao, Aaron W. Peters, Cornelius O. Audu, Zachary J. Brown, Omar K. Farha, Joseph T. Hupp and SonBinh T. Nguyen
Catalysis Science & Technology (2011-Present) 2015 - vol. 5(Issue 9) pp:NaN4451-4451
Publication Date(Web):2015/06/30
DOI:10.1039/C5CY00825E
A comparative study of the support effect in three different UiO-66-based MOFs – with TiIV supported as part of the node (UiO-66-Tiex), attached to the node (Ti-UiO-66), and on a catecholate organic linker (UiO-66-Cat-Ti) – is reported. The three MOFs were evaluated for their catalytic activity and selectivity in cyclohexene oxidation. Ti-UiO-66 exhibited greater catalytic turnover numbers than UiO-66-Cat-Ti and UiO-66-Tiex.
Co-reporter:Debashis Adhikari, SonBinh T. Nguyen and Mu-Hyun Baik
Chemical Communications 2014 - vol. 50(Issue 20) pp:NaN2678-2678
Publication Date(Web):2014/01/07
DOI:10.1039/C3CC48769E
Epoxide and CO2 coupling reactions catalyzed by (salen)CrIIICl have been modeled computationally to contrast a monometallic vs. a bimetallic mechanism. A low-energy CO2 insertion step into the metal–alkoxide bond was located.
Co-reporter:Sai Archana Krovi, DeeDee Smith and SonBinh T. Nguyen
Chemical Communications 2010 - vol. 46(Issue 29) pp:NaN5279-5279
Publication Date(Web):2010/06/23
DOI:10.1039/C0CC00232A
The versatility of copper-catalyzed alkyne–azide coupling (CuAAC) in functionalizing drug-loaded polymer nanoparticles is demonstrated via the modification of surfaces of acetylene-functionalized PNPs with folate, biotin, and gold nanoparticles.
Co-reporter:Tendai Gadzikwa, Omar K. Farha, Karen L. Mulfort, Joseph T. Hupp and SonBinh T. Nguyen
Chemical Communications 2009(Issue 25) pp:
Publication Date(Web):
DOI:10.1039/B823392F
Co-reporter:Byungman Kang, Aaron W. Miller, Sandra Goyal and SonBinh T. Nguyen
Chemical Communications 2009(Issue 26) pp:NaN3930-3930
Publication Date(Web):2009/05/26
DOI:10.1039/B902647A
Sc(OTf)3 effectively catalyzes the condensation of 2-alkyl-N-tosylaziridine with a wide variety of aldehydes and ketones, producing 5-alkyl-1,3-oxazolidines in good yields and excellent regioselectivity at catalyst loadings as low as 1 mol%.
Co-reporter:Kyoung-Tae Youm, SonBinh T. Nguyen and Joseph T. Hupp
Chemical Communications 2008(Issue 29) pp:NaN3377-3377
Publication Date(Web):2008/06/27
DOI:10.1039/B800063H
Hollow, hexa-porphyrin prisms of two sizes were template-assembled and covalently locked, via cross-olefin metathesis, into permanent, torsionally rigid structures whose active sites (metal sites) can be both accessed and altered in a facile manner.
Co-reporter:Ryan V. Thaner, Ibrahim Eryazici, Omar K. Farha, Chad A. Mirkin and SonBinh T. Nguyen
Chemical Science (2010-Present) 2014 - vol. 5(Issue 3) pp:NaN1096-1096
Publication Date(Web):2013/12/06
DOI:10.1039/C3SC53206B
A broad range of synthetically challenging-to-access small molecule–DNA hybrids can be readily synthesized in “one pot” and in high yields by coupling multi-azide cores to alkyne-modified DNAs on a solid support using click chemistry. The multi-functional products can be obtained in pure forms and on large scales (1 μmol) in a facile fashion. In addition, the distribution of the products can be controlled by changing the concentration of the azide core in solution and the strand-loading density on the solid-supports.
Co-reporter:Debashis Adhikari, Aaron W. Miller, Mu-Hyun Baik and SonBinh T. Nguyen
Chemical Science (2010-Present) 2015 - vol. 6(Issue 2) pp:NaN1300-1300
Publication Date(Web):2014/11/21
DOI:10.1039/C4SC02785J
The (salen)Cr-catalyzed [aziridine + CO2] coupling to form oxazolidinone was found to exhibit excellent selectivity for the 5-substituted oxazolidinone product in the absence of any cocatalyst. Quantum mechanical calculations suggest that the preferential opening of the substituted C–N bond of the aziridine over the unsubstituted C–N bond is a key factor for this selectivity, a result that is supported by experiment with several phenyl-substituted aziridines. In the presence of external nucleophile such as dimethyl aminopyridine (DMAP), the reaction changes pathway and the ring-opening process is regulated by the steric demand of the nucleophile.
Co-reporter:Ibrahim Eryazici, Omar K. Farha, Owen C. Compton, Charlotte Stern, Joseph T. Hupp and SonBinh T. Nguyen
Dalton Transactions 2011 - vol. 40(Issue 36) pp:NaN9193-9193
Publication Date(Web):2011/08/08
DOI:10.1039/C1DT10671F
A new class of infinite coordination polymers (CP) was synthesized using a tetrahedral tetrakis[4-(4′-phenyl-2,2′:6′,2′′-terpyridine)phenyl]methane ligand as an organic node to direct the three-dimensional growth of the network and MII (M = Zn, Fe, Ni, and Ru) ions as inorganic linkers, an approach that is the opposite of the metal-as-a-node strategy used in the construction of metal–organic frameworks (MOFs). The unusual rod-like morphology of the resulting microporous materials can be tuned viasolvents and reaction conditions. The covalent entrapment of a [Ru(tpy)2]2+ moiety in the skeleton of the 3D-network enables the Ru-CP to exhibit room-temperature luminescence.
Co-reporter:Suk Joong Lee, Rebecca A. Jensen, Christos D. Malliakas, Mercouri G. Kanatzidis, Joseph T. Hupp and SonBinh T. Nguyen
Journal of Materials Chemistry A 2008 - vol. 18(Issue 31) pp:NaN3642-3642
Publication Date(Web):2008/07/08
DOI:10.1039/B804629H
A highly efficient porphyrin synthesis facilitates a systematic investigation of the effects that secondary substituents have on the physical properties, crystal structures, and nanoparticle morphologies of amphiphilic (porphyrin)Sn(OH)2.
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![1H-PYRROLE, 2-[(PENTAFLUOROPHENYL)-2H-PYRROL-2-YLIDENEMETHYL]-](http://img.cochemist.com/ccimg/630200/630110-81-5.png)
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![Chromium,chloro[[2,2'-[(1R,2R)-1,2-cyclohexanediylbis[(nitrilo-kN)methylidyne]]bis[4,6-bis(1,1-dimethylethyl)phenolato-kO]](2-)]-, (SP-5-13)-](http://img.cochemist.com/ccimg/165000/164931-83-3_b.png)
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![9-Octadecenoic acid(9Z)-, 1,1'-[1-[(dimethylamino)methyl]-1,2-ethanediyl] ester](http://img.cochemist.com/ccimg/127600/127512-29-2.png)
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![[1,1':3',1''-Terphenyl]-4,4''-diol](http://img.cochemist.com/ccimg/124600/124526-56-3.png)
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![1-Propanaminium,N,N,N-trimethyl-2,3-bis[[(9Z)-1-oxo-9-octadecen-1-yl]oxy]-](http://img.cochemist.com/ccimg/113700/113669-21-9.png)
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![[4,4',4'',4'''-(5,10,15,20-porphyrintetrayl-κ2n21,n23)tetrabenzoato(2-)]palladium](/data/chemimg/2070800/94288-44-5.png)
![[4,4',4'',4'''-(5,10,15,20-porphyrintetrayl-κ2n21,n23)tetrabenzoato(2-)]palladium](/data/chemimg/2070800/94288-44-5_b.png)
![Ethanol, 2-[(4-iodophenyl)methoxy]-](http://img.cochemist.com/ccimg/91000/90943-24-1.png)
![Ethanol, 2-[(4-iodophenyl)methoxy]-](http://img.cochemist.com/ccimg/91000/90943-24-1_b.png)
![BENZENE, 1-[(1,1-DIMETHYLETHYL)SULFONYL]-2-IODO-](http://img.cochemist.com/ccimg/69700/69649-28-1.png)
![BENZENE, 1-[(1,1-DIMETHYLETHYL)SULFONYL]-2-IODO-](http://img.cochemist.com/ccimg/69700/69649-28-1_b.png)
![Ferrate(4-), chloro[[4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl-κN21,κN22,κN23,κN24)tetrakis[benzoato]](6-)]-, hydrogen (1:4), (SP-5-12)-](/data/chemimg/99300/55266-17-6.png)
![Ferrate(4-), chloro[[4,4',4'',4'''-(21H,23H-porphine-5,10,15,20-tetrayl-κN21,κN22,κN23,κN24)tetrakis[benzoato]](6-)]-, hydrogen (1:4), (SP-5-12)-](/data/chemimg/99300/55266-17-6_b.png)
![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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![Tricyclo[3.3.1.13,7]decane, 1,3,5,7-tetraphenyl-](/data/chemimg/530700/16004-75-4.png)
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![3,5,9-Trioxa-4-phosphaheptacos-18-en-1-aminium,4-hydroxy-N,N,N-trimethyl-10-oxo-7-[[(9Z)-1-oxo-9-octadecen-1-yl]oxy]-, innersalt, 4-oxide, (7R,18Z)-](http://img.cochemist.com/ccimg/4300/4235-95-4.png)
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