Investigation of NLO properties of substituted (M)-tetrathia-[7]-helicenes by semiempirical and DFT methods

In this article, we propose a theoretical study of static and dynamic polarizability alpha, first hyperpolarizability beta, and second hyperpolarizability gamma of substituted (M) -tetrathia-[7]-helicenes. Both a semiempirical approach, in the case of static and dynamic properties, and density functional theory, in the case of static electric properties, were used. The nonlinear optical (NLO) properties of a set of 10 molecules were investigated to predict the couple of donor-acceptor substituents that could best enhance the optical properties of (M)-tetrathia-[7]-helicene. (C) 2002 Wiley Periodicals, Inc.