THEORETICAL INVESTIGATION OF THE GEOMETRIC STRUCTURES AND THE 2ND-ORDER NONLINEAR OPTICAL-PROPERTIES OF 8-HYDROXYQUINOLINE DERIVATIVES

We report here the coupled perturbed Hartree-Fock (CPHF) ab initio extended basis set calculations on the geometric structures and static first-order (alpha) and second-order (beta) polarizabilities of a series of 8-hydroxyquinoline molecules substituted by fluoro, chloro, nitro, and amino groups. Twenty one compounds were investigated in this study by considering the basis set dependence of the molecular hyperpolarizabilities. The effects of the nature and the position of the substituent on the geometry and the first-order and second-order polarizabilities are described. 2-Amino-6-nitro-8-quinolinol is calculated to have a beta(vec) of 14.739 x 10(-30) esu which is almost twice as large as that for p-nitroaniline. On the basis of these calculations, new trends for the molecular design of fused heterocyclic aromatic compounds for second-order nonlinear optical applications are proposed.