881302-73-4Relevant academic research and scientific papers
Two hydrogen-bonded organic frameworks with imidazole encapsulation: Synthesis and proton conductivity
Hao, Biao-Biao,Wang, Qinglun,Wang, Xin-Xin,Zhang, Chen-Xi
, p. 3908 - 3915 (2021)
On the basis of the carboxylic structure of trimesic acid (TMA) and 5-borono-1,3-benzenedicarboxylic acid (B-BDC), here two hydrogen-bonded organic frameworks (HOFs), HOF 1 (MA-TMA) and HOF 2 (MA-B-BDC), were prepared by reacting melamine (MA) with trimesic acid and 5-borono-1,3-benzenedicarboxylic acid, respectively. The as-prepared HOF 1 and HOF 2 with 3D supramolecular structure exhibit excellent performance in proton transport. AC impedance test shows that the proton conductivities of HOF 1 and HOF 2 reach 3.11 × 10-4 S·cm-1 (343 K, 98% RH) and 4.32 × 10-4 S·cm-1 (323 K, 98% RH), respectively. To increase the proton conductivity, Im@HOF 1 and Im@HOF 2 were obtained by introducing imidazole (Im), which acts as a jumping site for proton transfer. The proton conductivities of Im@HOF 1 and Im@HOF 2 reached 4.12 × 10-4 S·cm-1 (333 K, 98% RH) and 1.20 × 10-3 S·cm-1 (353 K, 98% RH), respectively. This is the first time that guest molecules were introduced into HOFs. The stability and proton conductivity of the HOFs are improved due to the interaction of imidazole with carboxyl groups and water molecules.
The Origin of Catalytic Benzylic C?H Oxidation over a Redox-Active Metal–Organic Framework
Carter, Joseph H.,Day, Sarah J.,Han, Xue,Kang, Xinchen,Kimberley, Louis,Li, Jiangnan,McInnes, Eric J. L.,Schr?der, Martin,Sheveleva, Alena M.,Smith, Gemma L.,Tang, Chiu C.,Tuna, Floriana,Yang, Sihai
supporting information, p. 15243 - 15247 (2021/06/08)
Selective oxidation of benzylic C?H compounds to ketones is important for the production of a wide range of fine chemicals, and is often achieved using toxic or precious metal catalysts. Herein, we report the efficient oxidation of benzylic C?H groups in a broad range of substrates under mild conditions over a robust metal–organic framework material, MFM-170, incorporating redox-active [Cu2II(O2CR)4] paddlewheel nodes. A comprehensive investigation employing electron paramagnetic resonance (EPR) spectroscopy and synchrotron X-ray diffraction has identified the critical role of the paddlewheel moiety in activating the oxidant tBuOOH (tert-butyl hydroperoxide) via partial reduction to [CuIICuI(O2CR)4] species.
An rht type metal-organic framework based on small cubicuboctahedron supermolecular building blocks and its gas adsorption properties
Li, Liangjun,Tang, Sifu,Lv, Xiaoxia,Jiang, Min,Wang, Chao,Zhao, Xuebo
supporting information, p. 3662 - 3670 (2013/11/06)
A metal-organic framework NPC-5 was synthesized via reaction of a methyl-functionalized ligand 2,4,6-trimethyl benzene-1,3,5-triyl-isophthalate (TMBTI) with Co(NO3)2·6(H2O) under solvothermal conditions. The steric hindrance induced by the methyl groups on the central phenyl ring led to a non-planar configuration of the ligand and further resulted in a small cubicuboctahedron SBB sustained (3, 24)-connected rht network, which comprised three types of cages and exhibited high porosity. Experimental results showed that despite the use of different synthetic methods the same structure was obtained. Gas sorption study of this MOF revealed high CO2 and CH4 uptake capacities and relatively low adsorption enthalpies.
High capacity hydrogen adsorption in Cu(II) tetracarboxylate framework materials: The role of pore size, ligand functionalization, and exposed metal sites
Lin, Xiang,Telepeni, Irvin,Blake, Alexander J.,Dailly, Anne,Brown, Craig M.,Simmons, Jason M.,Zoppi, Marco,Walker, Gavin S.,Thomas, K. Mark,Mays, Timothy J.,Hubberstey, Peter,Champness, Neil R.,Schroeder, Martin
experimental part, p. 2159 - 2171 (2009/07/30)
A series of isostructural metal-organic framework polymers of composition [Cu2(L)(H2O)2](L= tetracarboxylate ligands), denoted NOTT-nnn, has been synthesized and characterized. Single crystal X-ray structures confirm the complexes to contain binuclear Cu(II) paddlewheel nodes each bridged by four carboxylate centers to give a NbO-type network of 6 4? 82 topology. These complexes are activated by solvent exchange with acetone coupled to heating cycles under vacuum to afford the desolvated porous materials NOTT-100 to NOTT-109. These incorporate a vacant coordination site at each Cu(II) center and have large pore volumes that contribute to the observed high H2 adsorption. Indeed, NOTT-103 at 77 K and 60 bar shows a very high total H2 adsorption of 77.8 mg g -1 equivalent to 7.78 wt% [wt% = (weight of adsorbed H 2)/(weight of host material)] or 7.22 wt% [wt% = 100(weight of adsorbed H2)/(weight of host material + weight of adsorbed H 2)]. Neutron powder diffraction studies on NOTT-101 reveal three adsorption sites for this material: at the exposed Cu(II) coordination site, at the pocket formed by three {Cu2} paddle wheels, and at the cusp of three phenyl rings. Systematic virial analysis of the H2 isotherms suggests that the H2 binding energies at these sites are very similar and the differences are smaller than 1.0 kJ mol-1, although the adsorption enthalpies for H2 at the exposed Cu(II) site are significantly affected by pore metrics. Introducing methyl groups or using kinked ligands to create smaller pores can enhance the isosteric heat of adsorption and improve H2 adsorption. However, although increasing the overlap of potential energy fields of pore walls increases the heat of H2 adsorption at low pressure, it may be detrimental to the overall adsorption capacity by reducing the pore volume.
Tailoring a bacteriochlorin building block with cationic, amphipathic, or lipophilic substituents
Ruzie, Christian,Krayer, Michael,Balasubramanian, Thiagarajan,Lindsey, Jonathan S.
, p. 5806 - 5820 (2008/12/21)
(Chemical Equation Presented) Bacteriochlorins are attractive candidates for photodynamic therapy (PDT) of diverse medical indications owing to their strong absorption in the near-infrared (NIR) region, but their use has been stymied by lack of access to stable, synthetically malleable molecules. To overcome these limitations, a synthetic free base 3,13-dibromobacteriochlorin (BC-Br3Br13) has been exploited as a building block in the synthesis of diverse bacteriochlorins via Pd-mediated coupling reactions (Sonogashira, Suzuki, and reductive carbonylation). Each bacteriochlorin is stable to adventitious dehydrogenation by virtue of the presence of a geminal dimethyl group in each pyrroline ring. The target bacteriochlorins bear cationic, lipophilic, or amphipathic substituents at the 3- and 13- (β-pyrrolic) positions. A dicarboxybacteriochlorin was converted to amide derivatives via the intermediate diacid chloride. A diformylbacteriochlorin was subjected to reductive amination to give aminomethyl derivatives. A set of 3,5-disubstituted aryl groups bearing lipophilic or amphipathic groups was introduced via Suzuki coupling. Altogether 22 free base bacteriochlorins have been prepared. Eight aminoalkylbacteriochlorins were quaternized with methyl iodide at two or four amine sites per molecule, which resulted in water solubility. Each bacteriochlorin exhibits a Qy absorption band in the range of 720-772 nm. The ability to introduce a wide variety of peripheral functional groups makes these bacteriochlorins attractive candidates for diverse applications in photomedicine including PDT in the NIR region.
Unidirectional threading synthesis of isomer-free [2]rotaxanes
Wang, Qiao-Chun,Ma, Xiang,Qu, Da-Hui,Tian, He
, p. 1088 - 1096 (2007/10/03)
The threading of an α-cyclodextrin (α-CyD) by an unsymmetrical dumbbell generally results in two isomeric [2]rotaxanes differing in the orientation of the α-CyD. In this work, two methods have been developed for the unidirectionally threading an α-CyD to
