Thieno[3,4-b]pyrazine-based oligothiophenes: simple models of donor-acceptor polymeric materials.

A series of thieno[3,4-b]pyrazine-based oligomers were synthesized via Stille cross-coupling as models of electronic structure-function relationships in thieno[3,4-b]pyrazine-based conjugated materials. The prepared oligomers include two oligothieno[3,4-b]pyrazine series from monomer to trimer, as well as a series of mixed terthienyls in which the ratio of thieno[3,4-b]pyrazine to either thiophene or 3,4-ethylene-dioxythiophene has been varied. The full oligomeric series was then thoroughly investigated via photo-physical and electrochemical studies, along with theoretical calculations, in order to correlate the effect of conjugation length and oligomer composition with the resulting electronic and optical properties. The corresponding relationships revealed should then provide more advanced models for the elucidation of donor-acceptor interactions in both homopolymeric and copolymeric materials of thieno[3,4-b]pyrazines.