Abstract: The geometry structure, electronic spectra and nonlinear second-order optical properties of 2,2′-spirobiindan-1,1′,3,3′-tetraone and it′s derivatives were investigated by using AM1 and ZINDO series method. The calculated UV-Vis spectra is in good agreement with the observed value; All studied molecule has no absorption above 400 nm, that is to say, these molecule has a good transparence. The relationship between the nonlinear second-order optical properties and the studied molecular structures of the compound and its derivatives was studied. The calculated results show that the electronic donating substituents attached on 5 position and the electronic withdrawing substitutents attached on the 5′ position have the highest nonlinear second-order ooptical susceptibilities these molecules are potential NLO materials due to the good transparence as well as large nonlinear second-order optical susceptibilities.

Key words: Spiroconjugation, 2,2′-spirobiindan-1,1′,3,3′-tetraone, AM1, ZINDO-SOS, Nonlinear second-order optical susceptibilities