Amphoteric Quinone–azine–cyclopentadithiophene System

Various quinoid groups have been connected with the cyclopentadithiophene (CPDT) skeleton via azine linkage to form a new D–(pi)–A system. These compounds revealed weak absorptions extending to 590–630 nm, corresponding to small HOMO– LUMO gaps of 1.97–2.10 eV. Their reduction potentials were strongly dependent on the quinone moieties, whereas the oxidation potentials were controlled by the CPDT moiety. Some of these compounds underwent oxidative polymerization under electrochemical conditions to yield polymers with a highly amphoteric character.