Conformational analysis of 3,3′-, 3,4′- and 4,4′-dimethoxy-2,2′-bithiophenes as models for related polymers

Abstract

An analysis of ¹³C chemical shifts of quaternary carbons of 3,3′-, 3,4′- and 4,4′-dimethoxy-2,2′-bithiophenes indicates they can be a useful tool for the identification of the inter-ring junction type. UV spectra and theoretical calculations are used to perform a conformational analysis of the compounds. The results show that the compounds prefer a non-planar conformation in non-condensated phases. The reasons for this non-planarity of the dimers and the effect on related polymers are discussed.