Theoretical study of the conversion reaction of sulfoxide, sulfone and xanthate precursors into conducting polymers

Abstract

A number of factors in the precursor synthetic routes towards conjugated materials have a substantial impact on the microstructure of the final material, including the amount of defects in the conjugation and the remaining groups on the backbone. These defects and substituents will in tum rule the conductive and light-emitting properties of the polymer. 1n order to achieve better control of the microstructure and of the elimination process, it is essential to understand in detail the mechanism of the conversion steps of the different precursors, and the factors which may lead to changes in the mechanism. In this context, quantum-chemical calculations help in providing accurate structure-property relationships, as well as valuable qualitative and quantitative insights into the reaction. Indeed, on the experimental side, it is extremely difficult, or even impossible, to focus on so many different and competitive reaction pathways, such as the internal conversion of the precursor into the trans- or cis-products, radical bond dissociations, cross-linked structures ... or to determine the effect of sterical hindrances. The main goal of the present thesis is therefore to provide both qualitative and quantitative insights into the most critical step of these precursor routes, namely the internal conversion itself. The influence of substituents on the reaction characteristics, possible side reactions, .. . will also be studied in detail. In Chapter HI we extend our investigations to the suitability of the sulfoxide route for the making of new PPV derivatives, which are thought of to exhibit interesting properties, of relevance for the engineering and development of further low band gap materia1s with improved characteristics. The conversion of three attractive types of precursor polymer chains with sulfoxide, sulfonyl and xanthate leaving groups into conjugated polymers is analyzed in detail.