Theoretical Study of Hyperpolarizabilities of Spirolinked Push−Pull Polyenes

The molecular hyperpolarizabilities, β, of spirolinked push−pull polyenes, 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 calculations. It is concluded that the spiroconjugation path is applicable to an intervening backbone between the electron-donating and the electron-withdrawing groups, and spirolinked push−pull polyenes have a possibility to be excellent second-order nonlinear optical materials from the standpoint of transparency and relatively large β values.