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 7π electron rings fused to a naphthalenene 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. It was transformed to 1,8-Bis (dibromomethyl)-4,5-dichloronaphthalene by 5 reaction steps. The dibromide was reacted with cis-4,5-bis (boryl) octene, prepared from bis [pinacolato] diboron and 4-octyne, to yield a pleiadene derivative. However, the yield was very low and not improved by modification of reaction conditions. Then we have adopted the intramolecular Friedel-Crafts type reaction for construction of the 7-membered ring. We have synthesized acepleiadiene (5, R=H) and acepleiadylene (6, R=H) by the latter method and found 5( … More R=H) showed a comparable 1^<at> oxidation peak as that of TTF by CV measurement. Efforts to obtain 1(R=H) via pleiadiene are in progress. Tellurophene-TCNQs (2, n=1, R=H) are only ones left unknown among Hetero-TCNQs, Synthesis of 2 is started from tellurophene. It was converted to 2,5-bis (hydroxymethyl) derivative via 3 reaction steps. Transformation of hydroxymethyl group to dicyanomethylene group to obtain 2 (n=1, R=H) is now actively sudying. Chrysene-TCNQ and -quinone (3) have a unique extended conjugated π-system and are expected to be very stable and have very low coulombic repulsion in their oxidation states. Its synthetic plan through a key intermediate, 2,8- dimethoxychrysene, was progressed. The key compound was obtained in a fairly short steps of reaction and its conversion to 3 is now scrutinized. Phenanthrene-TCNQ and -quinone (4) are unique and assumed to be a strong acceptor, because they have a oquinoid partial structure. Its synthetic plan via 3,6-dibromo- or 3,6-dimethoxy-phenanthrene was executed with success. Both key intermediates were obtained in good yields from the corresponding biphenyls. A green solid compound, which has a very low solubility to common organic solvents, appeared to be 4 (R=C(CN)_2) was obtained by the two successive reactions, substitution of bromine of the former key compound with dicyanomethyl anion and oxidation, We are now actively studying its structure and properties.JA01K Less