The structural and electronic properties of neutral and oxidized terthiophenes substituted with polyarom. systems have been investigated using a combination of both Raman and electronic absorption spectroscopy in conjunction with d. functional theory calcns. Naphthylethenyl terthiophene exhibits structural and electronic properties, in both the neutral and oxidized species, that are dominated by the terthiophene backbone, in a manner similar to that previously reported for phenylethenylterthiophene. Anthracenylethenyl terthiophene, on the other hand, displays properties that are dominated by the anthracene group. Unlike both phenylethenyl and naphthylethenyl terthiophene, which have electronic absorption spectra dominated by transitions between MOs that are delocalized throughout the mols., the absorption spectrum of anthracenylethenyl terthiophene consists of a simple addn. of the absorption bands of the sep. terthiophene and anthracenylethene chromophores. This is the result of a spatial partitioning of its MOs that effectively electronically decouples the anthracene and terthiophene moieties. Upon oxidn., the naphthylethenylterthiophene s-dimerizes to form sexithiophene charged species and spectral signatures of the sexithiophene backbone are evident in both the electronic absorption and resonance Raman spectra. In contrast, these signatures are absent in the corresponding spectra of the oxidized anthracenylethenylterthiophene, suggesting that the anthracene group is the primary site of the structural changes induced by oxidn.