Abstract: 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 β value increases much. The calculated β₀ value of the unsubstituted subphthalocyanine agrees well which the experimental result, they are -0.73×10^-28 and -0.70×10^-28 esu, respectively. The β₀ of the studied compound with the longest conjugated chain increases one order of magnitude, -1.47×10^-28 esu, in contrast to that of the unsubstituted subphthalocyanine.

Key words: Subphthalocyanine, Electronic spectrum, Nonlinear optical property, INDO/CI