Tetsuya Jigami

Synthesis, structure, and polymerization of 2,2'-bitellurophene

Abstract 2-2′-Bitellurophene was prepared in one-pot from tellurophene. Its molecular and crystal structures were elucidated by an X-ray crystal analysis. Its electrochemical polymerization gave poly(bitellurophene) as a black film or powder, which had an electrical conductivity in the range of 10−6−10−9 Scm−1.

2,2′-Bitellurophene and 2,2′:5′,2″-tertellurophene as novel high homologues of tellurophene☆

Abstract The title heterocycles were prepared from tellurophene, and their spectroscopic and electrochemical properties were systematically compared together with those of other chalcogenophene congeners. Their electropolymerizations gave poly(bitellurophene) and poly(tertellurophene) as black films, which both had higher electrical conductivities than poly(tellurophene) similarly obtained.

Synthesis and properties of novel heterocycle-fusedTTF-type electron donors: bis(propylenethio)tetrathiafulvalene (BPT-TTF),bis(propyleneseleno)tetrathiafulvalene (BPS-TTF), andtheir tetraselenafulvalene analogues (BPT-TSF and BPS-TSF)

A series of novel heterocycle-fused TTF-type electron donors, bis(propylenethio)tetrathiafulvalene (BPT-TTF, 5), bis(propyleneseleno)tetrathiafulvalene (BPS-TTF, 6), and their tetraselenafulvalene analogues (BPT-TSF, 7 and BPS-TSF, 8) have been effectively synthesized from a common starting compound, THP-protected pent-4-yn-1-ol. The solution electrochemistry reveals that all the new donors have good electron donating properties. Formation of their radical cation salts by electrocrystallization technique has been successfully achieved. All the radical salts derived from the TTF derivatives (5 and 6) are insulating owing to the complete charge transfer. On the other hand, the TSF derivatives (7 and 8) afford different types of highly conductive radical cation salts. Of these, 7·PF6, 7·AsF6 and 7·FeCl4 remain metallic down to liquid helium temperature.

Conducting complexes of TTF and TSF derivatives fused with selenium-containing five-membered rings

Electrocrystallization of bis(ethyleneseleno)-tetrathiafulvalene (BES-TTF) and -tetraselenafulvalene (BES-TSF) gave a variety of radical cation salts which had high room-temperature conductivities (60-280 S cm -1 ) and displayed a metal-to-semiconductor (insulator) transition at low temperature. Among them, however, the ClO 4 - and AsF 6 - salts of BES-TSF remained highly conducting even at cryogenic temperature. An X-ray crystallographic analysis of (BES-TTF) 2 SbF 6 , revealed that the complex carries a considerably two-dimensional interactive electronic structure.

3,4-Thienylene-ethynylene Oligomers

Several well-defined 3,4-thienylene-ethynylene oligomers with different chain lengths have been synthesized and characterized. X-Ray crystallographic analyses proved their unique, totally helical conformations.

Novel selenium variants of BEDT-TTF

Bis(ethyleneselenothio)-tetrathiafulvalene (BEST-TTF) and -tetraselenafulvalene (BEST-TSF) have been synthesized using the following two consecutive cyclization methods: (1) one-pot construction of the inner 1,3-dichalcogenole ring from THP-protected 2-(ethynylthio)ethanol and (2) intramolecular transalkylation on a selenium atom toward the formation of the outer dihydrothiaselenin ring. The X-ray crystallographic analysis of BEST-TSF revealed that its molecular and crystal structures are essentially similar to those of BEDT-TTF and related selenium variants.

Structures and Properties of Radical Cation Salts of Novel Tetraselenafulvalene Derivatives (BPT-TSF, EDT-PT-TSF, and BEST-TSF) with MX 4 (M = Fe, Ga, X = Cl, Br)-Type Anions

Using three different BETS variants (BPT-TSF 2 , EDT-PT-TSF 3 , and BEST-TSF 4 ), six new radical cation salts of D 2 MX 4 -type are prepared. The κ-type salts with FeCl 4 − anion obtained from the donors 2 and 3 are isostructural with the corresponding BETS salts. From the donor 3 , a radical salt with β-type donor packing is obtained with GaCl 4 − anion. All these salts from donors 2 and 3 are metallic down to low temperature. On the other hand, the donor 4 possessing selenium atoms in outer heterocycles gives two λ-type salts. They are highly conductive at room temperature, but not metallic at low temperature range.