Structural and spectroscopic properties of a set of donor-acceptor molecules with and without spacers: Part 2. Piperonyl and julolidyl groups as donors
1992 (English)In: Journal of Molecular Structure: THEOCHEM, ISSN 0166-1280, Vol. 262, 273-285 p.Article in journal (Refereed) Published
A series of donor-acceptor polyenes exhibiting potential switching properties are studied using semiempirical techniques. Heats of formation, ionization potentials, dipole moments and molecular geometries for the ground states are obtained from MNDO and AM1 calculations, whereas the properties of the excited states are provided by the spectroscopic model zindo. The differences in the description of the ground state properties are, except for torsional angles, minor between MNDO and AM1, and it is found that AM1 systematically predicts more planar structures. For some of the molecules PM3 calculations were performed, leading to geometry descriptions very similar to those obtained with AM1. The HOMOs and LUMOs are delocalized in the systems where no spacer is present, and localized on the donor part and on the acceptor part, respectively, in the systems where an insulating spacer is included. In the former systems, no significant charge transfer effects are observed when exciting from the ground states. In the latter systems, the HOMO to LUMO transitions result in a significant charge transfer effect, although with very low probabilities.
Place, publisher, year, edition, pages
1992. Vol. 262, 273-285 p.
IdentifiersURN: urn:nbn:se:uu:diva-150648DOI: 10.1016/0166-1280(92)85113-YOAI: oai:DiVA.org:uu-150648DiVA: diva2:408145