Tuning of Electronic Properties of π-Conjugated Polymers Possessing 1,4-Mercapto-1,3-butadiene-1,4-diyl Units by Variation of Oxidation States of Sulfur Atoms

Abstract

A π-conjugated polymer having 1,4-bismercapto-substituted 1,3-diene units in the main chain, prepared by the reaction of a polymer possessing titanacyclopentadiene-2,5-diyls units with benzenesulfenyl chloride (PhSCl), was subjected to the oxidation with m-chloroperoxybenzoic acid (mCPBA) to control optoelectronic properties of the resulting materials. That is, polymers possessing sulfoxide- and/or sulfone-substituted 1,3-diene units were obtained by the oxidation reactions of the polymer having phenylmercapto moieties with varied amount of mCPBA. Electrochemical properties of the resulting sulfoxide- and/or sulfone-containing polymers were studied by their cyclic voltammetric analyses, from which their HOMO and LUMO energy levels proved to be tunable by the oxidation states of the sulfur atoms (HOMO = −5.1–−5.7 eV and LUMO = −2.7–−3.1 eV).