Ab Initio Study on One-Way Photoisomerization of the Maleic Acid and Fumaric Acid Anion Radical System as a Model System of Their Esters
journal contributionposted on 09.11.2006, 00:00 by Masato Sumita, Kazuya Saito
Potential energy surfaces (PESs) of the maleic acid anion radical (MA-•: cis isomer)/fumaric acid anion radical (FA-•: trans isomer) system as a model system of their esters have been studied in detail using CASSCF method. The results suggest the following: The photoisomerization is initiated with the H−C−C−H dihedral angle distortion [hydrogen out of plain (HOOP) motion] on the D1 PES. The C−C−C−C dihedral angle distortion occurs on the D0 PES after the deactivation from D1 to D0. A large fraction of the net motion along the isomerization coordinate occurs on the D0 PES. The D0 state is responsible for the one-way nature of the photoisomerization.