Theoretical study on electronic spetra and nonlinear optical properties of subphthalocyanines substituted by NO2 groups

Based on the geometries optimized via AM1 method, the effects of the peripheral NO2 group substituents of subphthalocyanine(C24H12B1Cl1N6) on the electronic spectra and second order nonlinear optical properties were observed by using INDO/CI-SOS method. The results show that the strong electron-withdrawing groups and the increased length of conjugated chain have the less effect on the structure and the maximum absorption wavelength, but have the more effect on the second order nonlinear optical properties. With increasing of the length of conjugated chain, the beta value increases much. The calculated beta(0) value of the unsubstituted subphthalocyanine agrees well which the experimental result, they are - 0.73 X 10(-28) and -0.70 x 10(-28) esu, respectively. The beta(0) of the studied compound with the longest conjugated chain increases one order of magnitude, -1.47 x 10(-28) esu, in contrast to that of the unsubstituted subphthalocyanine.