SYNTHESES OF NEW ORGANIC ELECTRON DONORS,ACCEPTORS,AND THEIR CHARGE-TRANSFER COMPLEXES,AND STUDIES ON THEIR PROPERTIES

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The target molecules of this research projects are novel organic electron donors (1) and acceptors (2, 3, 4), which are expected to act as effective components to form charge-transfer complexes exhibiting high electric conductivities. The molecule, 1, carries two 7pi electron rings fused to a naplithalenene at its two peri-positions and is expected to behave as a good electron donor in the two stage redox processes. Synthesis of 1 is started from acenaphthene and are first dichiorinated its peri-positins then transformed its 5-membered ring to a cyclic anhydride via bromination with NBS and the following oxidation. The diol obtained by LAH reduction of the anhydride was transformed to 1, 8-Bis(dibromomethyl)4, 5-dichioronaphthalene. The dibromide was reacted with cis-4, 5-bis(boryl)octene, prepared from bis[pinacolato]diboron and 4-octyne, to yield a pleiadene. Efforts to obtain 1 (R=n-Pr) in progress. Tellurophene-TCNQs (2) are only ones left unknown amoung Hetero-TCNQs. Synthesis of … More 2 is started from tellurophene, which is prepared by 1,4-bis(TMS)-1, 3-butadiyne and Na_2Te and then converted to 2, 5-dicarboxylic acid via 6 steps. Transformation of carboxyl group to dicyanomethylene group to obtain 2 (xl, R=H) is now actively sudying. Crysene-TCNQ (3) has a unique extended conjugated pi-system and expected to be very stable and have very low coulombic repulsion in their oxidation states. Their synthesis are planned to couple a 2-bromo-6-methoxynaphthalene and 2-bromo-5-methoxybenzaldehyde by Suzuki-Miyaura method to yield a key intermediate to lead 2, 8-dimethoxyclirysene. The coupling reaction is now scrutinized. Phenanthrene-TCNQ (4) is unique and assumed to be a strong acceptor, because it has a oquinoid partial structure. Its synthesis is planned to execute via a biphenyl derivative, which is obtained from 2-bromo-5-methoxytoluene and N,N-diethy1-4-methoxybenzamide by a combination of Suzuki-Miyaura and Snieckus coupling methods. The biphenyl derivative is subjected to metalatation, intramnoleculari condensation followed dehydroxylic elimination to afford a key phenanthrene derivative, 3, 6-dimethoxyphenanthrene. Now we are actively investigating coupling reaction conditions and procedures to obtain the biphenyl derivatives. Although we do not yet have the target molecules in our hands, we are closely approaching our targets and very sure to be able to get them in near future. Less