M. Breza, Vladimír Lukes, I. Vrábel
Sep 17, 2001
Citations
0
Influential Citations
30
Citations
Journal
Journal of Molecular Structure-theochem
Abstract
Abstract The geometries of 2,2′-bithiophene, 2,2′:5′,2″-terthiophene and 2,2:5′,2″:5″,2′‴-quaterthiophene molecules were optimized by using semiempirical AM1 method for fixed equidistant dihedral angles between neighboring thiophene rings. Corresponding electron spectra are calculated by semiempirical AM1 and ZINDO/S methods. The vibronic interaction between the low lying monoexcited electronic states is symmetry forbidden for any torsion coordinate in all planar oligothiophenes and similar compounds because these electron states are constructed from π molecular orbitals. Mutual orientation of torsion angles is not important for electronic structure of oligothiophenes. The dependence of maximal wavelength λ max on the torsion angle is of similar shape as its squared sine function. Using this dependence the torsional angles for some alkylated oligothiophenes in solution are estimated.