|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1993 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1992 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Synthesis of new organic donors and acceptors aimed toward organic superconductors, and characterization of their conductors are attempted.
1. New synthesis route of TTF(tetrathiafulvalene) derivatives using organoaluminium reagents is developed, and several new TTF derivatives are prepared.
2. A number of new donors where tetrathiapentalene is inserted into the center of TTF, are synthesized, and its structuers and physical properties are investigated. (1) TMEO-TTP, which has methylthio moieties on one side and an ethylenedioxy group on another side, formed metallic salts with octahedral and tetrahedral anions. (2) TTM-TTP, which has methylthio groups on both sides, formed three I3 salts. One of them, which is metallic instead of 1 : 1 composition, has one-dimensional columnar structure. One of the 2 : 1 salts is metallic down to 20 K.(3) EDT-TTP, which is substituted by an ethylenedithio group on one side and unsubstituted on another side, gave many metallic salts at room temperature. (4) Mose salts of unsubstituted BDT-TTP are metallic down to low temperatures independently of the counter anions. These salts have so-called beta-typestructure, and the metallic states are stablized because intercolumnar interaction is as large as one third to one fourth of the intracolumnar interaction.
These results show that the extension of the TTF skeleton effectively stabilizes the metallic states of the organic conductors. Other possiblities of substituents and anions are under investigation.