Syntheses and properties of π-conjugated polymers containing tetrathiafulvalene in the polymer backbone

Syntheses of π-conjugated polymers containing tetrathiafulvalene (TTF) in the polymer backbone were successfully attempted from dibrominated TTF derivatives and diboronic acid derivatives using the Suzuki coupling reaction. The present polymers showed high molecular weight (12,900–36,700) and excellent solubility in conventional organic solvents, suggesting the effect of the introduction of an alkoxy chain. Electrochromic phenomenon was observed using spin-coated film of the polymers on ITO glass plate, and the color of the film changed reversibly from yellow to red purple depending on the applied potential. The response of the electrochromic change was rapid and reproduced over thousand times. Optoelectrochemical measurement for spin-coated film revealed that the color change was responsible for the electronic state of the TTF moiety, and the observed charge-transfer band was caused by the intermolecular interaction between TTF moieties in the different polymer backbones.