The nonlinear optical (NLO) properties of seven compounds using carborane and benzene rings as the bridging groups were investigated at the density functional theory (DFT) B3LYP method. The results indicate that a larger size bridging groups would be helpful in enhancing the polarizability. Electron delocalization of bridging group has an important influence on the second-order NLO coefficients as well as the molecular geometry, and the charge transfer has a greater contribution to the NLO properties. Moreover, from the analysis of electronic spectrum and the corresponding molecular orbit composition, it illustrates that the carborane can be not only the bridge for electron transmission, but also the electron withdrawing group.

Key words: carborane, electronic spectrum, NLO property, DFT