Creation of multi-dimensional structures of functional molecules by metal complexation reactions

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To construct new multi-dimensional functional molecular systems by utilizing complex reactions of transition metal complexes has been investigated in this research project. The molecular systems that have been focused are 1) azo-conjugated metal complexes with photo-functions, 2) donor-acceptor conjugated complexes with an ability of proton-coupled intramolecular electron-transfer reactions, and 3) metal nanoparticles modified with redox- and photo-functional complexes. The summary of the results is as follows.The trans-to-cis isomerization of azoferrocene proceeds not only by the photoexcitation of the π-π^* transition band but also by photoexcitation of the MLCT (d-π^* transition) band. The trans/cis ratio of the azobenzene-attached bipyridine ligands in their cobalt complex is reversibly altered by a combination of photoirradiation with a single UV light source and the reversible redox change between Co(II) and Co(III). A newly synthesized Ni, Pd and Pt tolylazophenylenedithiolato c … More omplexes 2-4 show reversible trans-to-cis photoisomerization, proto-chromism, and novel proton-coupled cis-to-trans isomerization.The protonation to carbonyl groups of the anthraquinone moiety in 1 -ferrocenylethynylanthraquinone causes intramolecular electron transfer leading to a novel structural change into a η^6-fulvene-cumulene Fe(II) complex. A 2:1 donor-acceptor complex, l,5-bis(ferrocenylethynyl)anthraquinone undergoes a two-step proton response, and the doubly protonated species involves a η^6-fulvene-Fe(II) complex-cumulene structure, and a novel spin-separated form of a ferrocenium (Fe(III)) ion and a semiquinone radical in the solution. Furthermore, the complex is in a thermal equilibrium between the valence tautomers of a donor-acceptor system in the solid state.Synthesis and electrochemical deposition behavior of biferrocene and anthraquinone derivative-modified Au and Pd clusters have been investigated. It is also possible to fabricate hetero structures by alternative electrodeposition of Bfc-modified gold and palladium nanoparticles. Less