EFFECT MOLECULAR-CONFORMATION ON THE ELECTRONIC-PROPERTIES OF DONOR-ACCEPTOR AZOBENZENES

Calculations are reported on the molecu lar conformation of methyl N-d imethylamino)-2'-nitroazobenzene-4'-carboxylate using the AM1 and PM3 methods. Of four possible conformers, those with the nitro-group trans to the ate-linkage are preferred. The conformation adopted has a cons iderable effect on the ground-state dipole moment and molecular hyperp olarisability which has been calculated using a sum-over-states semi-e mpirical approach. The results indicate that the conformation with the largest dipole moment favoured under electric field poling conditions has the smallest utilisable molecular hyperpolarisability.