Masashi Hasegawa

Synthesis and electrochromic properties of bis(2-tetrathiafulvalenylethynylphenyl)ethynes

Bis(2-tetrathiafulvalenylethynylphenyl)ethynes la and 1b have been synthesized by the Sonogashira coupling reaction of 4-iodotetrathiafulvalenes with bis(2-ethynylphenyl)ethyne. The dimeric TTFs la and 1b form an open-chain anti conformation in the neutral and tetracation states, whereas la and 1b form a helical syn conformation in the mono- and dication states owing to their face-to-face interaction between the two TTF units. Such conformational changes lead to unique electrochromic and on-off switching properties of la and 1b in UV-vis-NIR spectra.

Synthesis and complexation properties of a synthetic receptor, Z-tetrabenzohexadehydro[16]annulene

Abstract Z-Tetrabenzohexadehydro[16]annulene ( 1 ), a synthetic receptor, easily produces its silver(I) complexes both in solution and in the solid state. The X-ray analysis of the silver(I) complexes of 1 revealed unique structures of the dinuclear complexes.

Synthesis of biphenylenes and tetraphenylenes using copper-catalyzed coupling of arylzinc intermediates

Biphenylene and some of its 2,3,6,7- and 1,8-substituted derivatives were synthesized using the CuCl2-mediated intramolecular coupling of an organozinc species prepared from 2,2′-dilithiobiaryls with one or two molar equiv. of ZnCl2 or ZnBr2 in THF. Although most of the reactions of 2,2′-dilithiobiaryls with CuCl2 in THF in the absence of ZnCl2 or ZnBr2 led to biphenylenes as a major product, similar reactions of the organozinc species with CuCl2 in THF produced biphenylenes in much better yields, due to smooth transmetallation and reductive elimination reactions. In particular, the copper-mediated cyclization of benzannelated organozinc intermediates, prepared from equimolar proportions of 2,2′-dilithiobiaryls with ZnCl2, proceeded smoothly and selectively to afford the desired biphenylenes in 46–81% yield except for the reaction of the zinc intermediate derived from 4,4′,5,5′-tetramethoxy-2,2′-dilithiobiphenyl with ZnCl2 (1.0 molar equiv.). The reaction of the tetramethoxy-substituted organozinc species with CuCl2 produced 2,3,6,7,10,11,14,15-octamethoxytetraphenylene as a major product in 67% yield.

Synthesis and Properties of Thienylene-Ethynylene-Tetrathiafulvalene Oligomers

A series of thienylene-ethynylene-tetrathiafulvalene oligomers 1–6 have been synthesized by the Sonogashira reaction of iodo-tetrathiafulvalene derivatives with thienylethynes. The X-ray structure of 4,5-bis(2-thienylethynyl)tetrathiafulvalene (1b) revealed a planar structure of the molecule. The electronic spectra of neutral oligomers 1–6 suggest a partial intramolecular charge transfer between the TTF and thienylethyne units. The cyclic voltammetric measurements of 1–4 showed multi-redox processes.