NONLINEAR OPTICAL PROPERTIES OF NOVEL AND EFFECTIVE H-SHAPED CHROMOPHORES CONTAINING THREE PARALLEL AND NON-CONJUGATED D-π-A UNITS

H-shaped chromophores containing three parallel non-conjugated D-π-A units are effective chromophores with high hyperpolarizability and good optical transparency. The semi-empirical methods ZINDO, AM1, MNDO and PM3 were employed to study the effect of strength of acceptors and donors, and steric repulsion between substituents on static first hyperpolarizabilities (β0) and enhancements of β0 of the H-shaped chromophores. The results show that the H-shaped chromophore would exhibit the largest β0 and/or the largest enhancement of β0 of the chromophore when combination of a donor (D) and an acceptor (A) in a D-π-A unit is suitable.