THEORETICAL-STUDY OF HYPERPOLARIZABILITIES OF SPIROLINKED PUSH-PULL POLYENES

The molecular hyperpolarizabilities, beta, of spirolinked push-pull po lyenes, where the several 1,4-cyclohexadiene rings linked through the tetrahedral sp(3) carbon atoms and electron-donating and -withdrawing groups were introduced in the terminal 1,4-cyclohexadiene rings, were investigated through the ab initio and INDO/S molecular orbital calcul ations. It is concluded that the spiroconjugation path is applicable t o an intervening backbone between the electron-donating and the electr on-withdrawing groups, and spirolinked push-pull polyenes have a possi bility to be excellent second-order nonlinear optical materials from t he standpoint of transparency and relatively large beta values.