Syntheses of New Multifunctional Viologen Derivatives and their Application for New Materials

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We investigated In this research the syntheses and application of new multi-electron transfer systems related to the well-known redox function, viologen and their development to polymeric systems.As new multi-electron transfer systems, we synthesized viologen derivatives bearing azobenzene, substituted benzophenones, dihydronicotinamidet or crown ethers linked with various spacers.In these new systems, we could find some new behaviors based on the intramolecular interactions between functional groups, which were not observed between the corresponding intramolecular systems.In the viologen derivatives having substituted benzophenone or dihydro- nicatinamide structure, charge transfer complexation between these functional groups were observed. In these systems, the photoinduced electron relay were observed in the aprotic medium for the first time.By the comparison of the redox behaviors in the viologen derivatives having the azobenzene structure with various linkages, the electron relay in both groups was found to be most effective, when these groups were connected with propylene linkage due to the stacked conformation of both groups. In this case the direction of electron relay was controlled by pHs.In the viologen derivative having the crown ether structure, the Na_2S_2O_4 reduction of vialogen part was accelerated by the crown ether part in the mixed solvent of water and acetonitrile.In order to introduce the above-mentioned multi-electron transfer systems in the polymer, some new monomers were synthesized which have vinyl groups directly linked to the functional groups. and the copolymers were synthesized with the viologen and other functional groups having as direct pendants. In these copolymers, charge transfer complexation,and intramolecular electron transfer were also observed much extensively than those in the monomeric model systems.