| The nonlinear optical properties of 27 selected donor-acceptor isomeric derivatives of naphthalene, quinoline, quinazoline and triazanaphthalene, including electron donor molecules such as phenyl, aminophenyl, and N, N-dimethylaminophenyl, were discussed and compared with literature values. The theoretical calculations were performed with three different hybrid density functional theories (DFT) i.e. BPV86, B3LYP and B3PW91, and 6-311++G(2d,p) basis set was used. The results show that these molecular systems have large first static hyperpolarizabilities. In addition, the NLO response of these molecular systems decreases dramatically when the N, N-dimethylaminophenyl is replaced by aminophenyl or phenyl. This study is extended to the determination of AM1 semi empirical polarizability together with QSAR-quality empirical polarizability using Miller's scheme and molecular volume calculations from optimized geometries using HyperChem v7. Semi empirical AM1 and QSAR-quality empirical polarizability calculations showed poor quantitative agreement with the DFT results, but give excellent statistical correlation coefficients with the DFT values. This implies that the results of such lower calculations can suitably scale for predictive purpose. |
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