Low dipole moment large ss electrooptic chromophores based on exocyclic double bond conjugated bridge

Novel low dipole moment (mu) and large first hyperpolarizability (beta) ele ctrooptic chromophores have been designed based on the special characterist ic of reversed dipole moment in the excited state of exocyclic double bond (ECDB) conjugated bridge by the optimization of the substituted method, and their electronic and second-order nonlinear optical properties have been t heoretically investigated by employing the AM1/FF and ZINDO/S-CI approaches . By extending the conjugation length and optimizing the donor/acceptor str ength, the oscillator strength of the excited transition that contributes t o the molecular nonlinearity can be further enhanced. The designed chromoph ores possess a larger figure of merit (FOM) than that of 4-N,N-dimethylamin o-4'-nitrostilbene (DANS), and lower (5 D) ground state dipole moment.