Effect of molecular conformation on the electronic properties of donor–acceptor azobenzenes

Abstract

Calculations are reported on the molecular conformation of methyl 4-(N,N-dimethylamino)-2′-nitroazobenzene-4′-carboxylate using the AM1 and PM3 methods. Of four possible conformers, those with the nitro-group trans to the azo-linkage are preferred. The conformation adopted has a considerable effect on the ground-state dipole moment and molecular hyperpolarisability which has been calculated using a sum-over-states semi-empirical approach. The results indicate that the conformation with the largest dipole moment favoured under electric field poling conditions has the smallest utilisable molecular hyperpolarisability.