Theoretical and spectroscopic study of a series of styryl-substituted terthiophenes

Conformational analyses of 3'-[1E-2-(4-R-phenyl)ethenyl]-2,2':5',2' -terthiophenes revealed three important dihedral angles, and the potential energy surfaces for each of these angles calculated for three R-pet molecules using the HF/3-21G(d) method is discussed. It is therefore concluded that the experimental electronic absorption spectra qualitatively support the positions and trends in energies of the R-pet molecular orbital.