| Research Abstract |
As a new synthetic method of electrically conducting heterocyclic polymers having piーconjugation system along the polymer chain, we have developed dehalogenation polycondensation of dihaloaromatic compounds with zeroーvalent nickel complexes. (n X-ArーX + n Ni(0)Lm ーーーーー> (Ar)_n + n NiX_2Lm ; Ar : heteroaromatic unit).
For example, reactions of zeroーvalent nickel complexes ( e. g., a mixture of dis (1, 5ーcyclooctadiene) nickel(0), Ni(cod)_2, and 2, 2'ーbipyridine ) with 3-alkylー2-, 5-diiodothiophene led to polycodensation to give poly (3-alkyー2, 5-thienylene) (PRTh) with molecular weight of about 15000 - 150000. PRTH was soluble in chloroform and took a random coil conformation in chloroform solution. The film of PRTh was cast on a platinum plate electrode from the chloroform solution. The electrochemical oxidation (anion doping) of PRTh in a solution containing electrolytes was accompanied by color change of the film from yellow to blue, and the color change was reversible. This observation indicates that PRTh can be used in an electronic devise.
PiーConjugated copolymer, which was constituted of electronーaccepting 2, 5-thienylene ring and electronーdonating 2.5ーpyridine ring, was prepared by using zeroーvalent nickel complexes. Owing to its unique electronic structure, the copolymer shows stabilized electrochemically oxidized state. Besides the above mentioned polymers, we have studied preparation of other electrically conducting piーconjugated polymers, redox behavior of the polymers, and the electron change transfer phenomena of the polymers. Furthermore, we investigated basic basic aspects of coordination chemistry the preparation of polymers.
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