研究领域

Inorganic Chemistry

A primary goal of research in the Shimizu group is the preparation and characterization of novel porous solids. Textbook porous materials are aluminosilicates such as clays and zeolites. While the utility of these compounds cannot be disputed (detergents, catalysts), their structures and, therefore, their range of function, are limited by the fact they have only aluminum, silicon, and oxygen as constituent atoms. We employ a "metal-organic" approach to making porous solids. Essentially, Si and Al are replaced by a range of metals and the O2- anion is replaced by any number of organic ligands. The main advantage is much greater diversity with respect to structure and hence function of these solids. The main targets for these porous solids are their use as storage vessels, separators, and sensing agents for guests, particularly gaseous molecules such as H2, CH4, and CO2. A number of metal-organic frameworks (MOF's) have been reported which show ability to uptake and store H2, an important issue if hydrogen is to be viable for mobile fuel cell technology. In the Shimizu group, we focus on the use of metal sulfonates and metal phosphonates as these groups have the ability to bridge multiple metal centers and form very stable aggregates structures. As far as required skills, ligands typically require a 1-5 step synthesis accompanied by all the standard means of small molecule characterization (NMR, IR, MS, EA). Metal complexes are characterized by powder and single crystal X-ray diffraction, SS NMR, DSC/TGA, and by surface area measurements. Graduate students perform all aspects of the research including their own X-ray crystallography. Another project related to fuel cells is the synthesis of new H+ conducting membranes. This is related to the above in that, rather than using the sulfonate and phosphonate groups to actually bind metal centers, they are incorporated into polymer structures via metal ion templation. This serves to form new morphologies and aggregates of H+ conducting clusters. Again, the above techniques are required in addition to impedance spectroscopy.

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Reconciling order, stability, and porosity in phosphonate metal–organic frameworks via HF-mediated synthesisRoger K. Mah , Benjamin S. Gelfand , Jared M.Taylor and George K. H. Shimizu , Inorg. Chem. Front., 2015, 2, 273-277. DOI: 10.1039/C4QI00209A. Design of a Humidity-Stable Metal–Organic Framework Using a Phosphonate Monoester Ligand Benjamin S. Gelfand , Jian-Bin Lin and George K. H. Shimizu, Inorg. Chem., 2015, 54, 1185–1187. DOI:10.1021/ic502478u MOFs as proton conductors – challenges and opportunities Padmini Ramaswamy, Norman E. Wong, George K. H. Shimizu, Chem. Soc. Rev. 2014, DOI:10.1039/c4cs00093e. Pyridinium Linkers and Mixing Anions In Cationic Metal-Organic Frameworks Jian-Bin Lin, George K. H. Shimizu, Inorg. Chem. Front., 2014, DOI:10.1039/C3QI00065F (Issue Front Cover) Proton Conduction with Metal Organic Frameworks George K. H. Shimizu, Jared M. Taylor and SiRim Kim, Science, 2013, 341, 354-355. DOI: 10.1126/science.1239872 Enhancing Order and Porosity in a Highly Robust Tin(IV) Triphosphonate Framework Roger K. Mah, Melanie W. Lui, and George K. H. Shimizu Inorg. Chem., 2013, 52 (13), pp 7311–7313 DOI: 10.1021/ic400274e Zn7O2(RCOO)10 Clusters and Nitro Aromatic Linkers in a Porous Metal–Organic Framework Simon S. Iremonger, Ramanathan Vaidhyanathan, Roger K. Mah,and George K. H. Shimizu, Inorg. Chem., 2013, 52 (8), pp 4124–4126 DOI: 10.1021/ic302127y A Water-Stable Metal−Organic Framework with Highly Acidic Pores for Proton-Conducting Applications Jared M. Taylor, Karl W.Dawson, and George K. H. Shimizu*, J. Am. Chem. Soc. 2013, 135, 1193-1196. DOI:10.1021/ja310435e Enhancing Proton Conduction in a Metal–Organic Framework by Isomorphous Ligand Replacement SiRim Kim, Karl W. Dawson, Benjamin S. Gelfand, Jared M. Taylor, and George K. H Shimizu*, J. Am. Chem. Soc. 2013, 135, 963-966. DOI: 10.1021/ja310675x Enhancing Water Stability of Metal-Organic Frameworks via Phosphonate Monoester Linkers Jared M. Taylor, Ramanathan Vaidhyanathan, Simon S. Iremonger, and George K. H. Shimizu*, J. Am. Chem.Soc. 2012, 134,14338-14340.DOI: 10.1021/ja306812r Metal organophosphonate proton conductors Shimizu, G. K. H.,Taylor, J. M.; Dawson. K. W. in Metal Phosphonate Chemistry: From Synthesis to Applications; Clearfield, A.; Demadis, K., Eds.; RSC Publishing, London, 2011; pp. 493-524. Competition and cooperativity in CO2 binding by amine-modifed metal organic frameworks Vaidhyanathan, R.; Iremonger, S. S.; Shimizu, G. K. H.*; Boyd, P. G.; Alavi, S.; Woo, T. K.* Angew. Chem. 2012, 51, 1826. Phosphonate monoesters as carboxylate-like linkers for metal organic frameworks Iremonger, S. S.; Liang, J.; Vaidhyanathan, R.; Martens, I.; Shimizu, G. K. H.*, Daff, T. D.; Aghaji, M. A.; Yeganegi, S.; Woo. T. K.*, J. Am. Chem. Soc. 2011, 133, 20048. Post-combustion CO2 capture using solid sorbents: a review Samanta, A.; Zhao, A.; Shimizu, G. K. H., Sarkar, P.; Gupta, R.* Ind. Eng. Chem. Res. 2012, 51, 1438. A permanently porous van der Waals solid by using phosphonate monoester linkers in a metal organic framework Iremonger, S. S.; Liang, J.; Vaidhyanathan, R.; Shimizu, G. K. H.*, Chem Commun. 2011,47, 4430-4432. Facile proton conduction via ordered water molecules in a phosphonate metal organic framework Taylor, J.M,; Mah, R. K.; Ratcliffe, C. I.; Moudrakovski, I.; Vaidhyanathan, R.; Shimizu, G. K. H.* J. Am. Chem. Soc. 2010, 132, 14055–14057. Direct observation and quantification of CO2 binding in an amine modified nanoporous solid Vaidhyanathan, R.*; Iremonger, S. S.; Shimizu, G. K. H.*; Boyd, P. G.; Alavi, S.; Woo, T. K.* Science, 2010, 330, 650-653. An Amine Functionalized Metal Organic Framework for Preferential CO2 Adsorption at Low Pressures Vaidhyanathan, R.; Iremonger, S. S. Dawson, K. W.; Shimizu, G. K. H.*, Chem Commun. 2009, 5230-5233. Hot article also featured in C&E News, MRS Bulletin. Anhydrous Proton Conduction at 150 °C in a Nanoporous Metal-Organic Framework Hurd, J. A.; Vaidhyanathan, R.; Thangadurai, V.; Ratcliffe, C. I.; Moudrakovski, I. L.; Shimizu, G. K. H.* Nature-Chemistry, 2009, 1, 705-710. Cover article. Highlighted in RSC Chemistry World and many energy websites. Phosphonate and Sulfonate Metal Organic Frameworks Shimizu, G. K. H.*; Vaidhyanathan, R.; Taylor, J. M., Chem. Soc. Rev. 2009, 38, 1430 - 1449. Invited paper for special issue on MOFs.