Theoretical Study on Redox-adjustable Second-order Nonlinear Optical Responses of 12-Vertex [1-R-CB11-Me11]- Carborane Complexes

The second-order nonlinear optical ( NLO) properties of 12-vertex [ 1-R-CB11-Me-11](-) carborane complexes were investigated with the density functional theory ( DFT) method. The results indicate that both the electron-donating or electron-withdrawing substituents and the reversible redox reaction of molecules can affect the molecular geometry. By the force of natural bond orbital( NBO) charge and the electron spin density analysis, we conclude that the molecular oxidation center is in carborane cage. The oxidation reactions of molecules have a significant effect on changing the electronic character of carborane. Meanwhile, the oxidization of the carborane anion is more helpful to enhance the beta(tot) value, for instance the amino derivative of carborane. Therefore, the redox reaction of this carborane can be used to adjust the second-order NLO response effectively.