Department of Chemistry, School of Scienece, The University of Tokyo Inorganic Chemistry Laboratory (Nishihara Lab.)

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Zip code : 113-0033
7-3-1 Hongo Bunkyo-ku Tokyo Japan
Tel +81-3-5841-4346
Fax +81-3-5841-8063

Research

Creation of intelligent molecular systems

 Creation of molecules which alter their properties in response to external stimulus and assembling molecular structures by combining them precisely will achieve the development of newfangled molecular functional systems.
 We are putting effort into the creation of new molecular systems which can respond susceptibly to photo irradiation, electric field, magnetic field and chemical environment, the clarification of their structures and properties in various states, such as single molecules, single crystals, macromolecules, multi-nuclear clusters and two-dimensionally ordered structures. We are also challenging to fabricate molecular devices by arranging our functional molecules on interfaces of electrodes and metal nanoparticles. In addition, we are also developing new catalytic reactions utilizing the characteristic features of transition metal complexes and nanlparticles.

Creation of materials

π-conjugated transition metal clusters and polymer complexes

 One-dimensional π-conjugated polymers, which are also called conductive polymers, have not only the high electron conductivity but also various properties such as chromisms and light emitting. We are dealing with creation of new materials by accreting metal transition complexes to these conductive polymers. For example, we synthesized the &pi-conjugated metallo-organic complexes containing Co or Ru as the hetero atom by our originally-developed metalacycle polymerization method, and succeed the expression of photoconductivity and ferromagnetic interaction between metal cores.

Additionally, we developed the effective generation method of the π-conjugated multinuclear complexes of different kinds of metal atoms by taking advantage of metalladichalcogens (S, Se) which exhibit reversible redox activities and optical properties. We are comprehensively clarifying the relations of their crystal structures, optical properties, electronics characteristics and chemical reactivity.

Chromic metal complexes

 We are engaging in the designing and synthesis of metal complexes having ligands which contain organic photochromic molecules such as azobenzene, spiropyran, and diarylethene, and researches for the manifestation of new characteristics and phenomena. For instance, we discovered the reversible isomerization using monochromic light and controlling valence state of azobenzene-conjugated bipyridine cobalt complex and ferrocenylazobenzene, the platinum complex containing two azobenzene moieties which shows reversible conversion of the triple stable state by trichromatic light, the conversion from photosignal to electrosignal by a copper complex of ligand having photoswitchable coordination power, the redox control of photo memory depth in a ferrocenylspiropyran, and the conversion of electronic conversion between redox sites by photoirradiation in bis(ferrocenylethynyl)ethenes.

 We also discovered ferrocene-quinone type donor (D)-acceptor (A) conjugated molecules as a system which produces the generation of a valence tautomer driven by protonation, the dependency of the tautomers’ structures on the numbers and positions of substitution of donor-acceptor, and the temperature-dependent reversible structure conversion accompanying with the rearrangement of the conjugated system. In addition, we discovered that a system which forms one-dimensional column structure crystal due to the D-A interaction between molecules occurs the quick and reversible crystal structure conversion between the nano channel structure containing guest molecule and the closed structure devoid of the guest molecule.

Development of new metal complex catalysts

 We developed an aryl halide silylation reaction with hydrosilane catalized by a transition metal complex catalyst, and dendrimer-entrapped Rh nanoparticles as a highly active catalyst for olefin hydrogenation reaction.

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