Theoretical study on the photoinduced reaction of benzylthiothienoindolizine derivatives

Abstract

3-(Benzylthio)thieno[3,4-b]indolizine derivatives show significant spectral changes depending on the solvent. We have examined the possible factors, reaction and isomerization for the change. Geometry optimizations were performed at the B3LYP/6-31G(d) level. Based on the obtained geometry the electronic transitions were predicted by the TD-B3LYP calculation. Potential energy curves as for the dihedral angle change of the exocyclic sulfide linkage were examined. The barrier height from gauche to trans isomer was calculated to be about 5 kJ mol-1. TD calculation shows that the protonation on the carbonyl oxygen effectively changes the absorption spectrum.