Synthesis, structure, and optical properties of 1,4-dithiafulvene-based nonlinear optic-phores

Polyenic nonlinear optic (NLO)-phores with a proaromatic 1,4-dithiafulvene electron donor and the little explored 1,1,3-tricyano-2-phenylpropene acceptor have been synthesized. Their configurational and conformational features, ground state polarization, and linear and nonlinear optical properties have been determined experimentally and theoretically, and the results are compared to those of tetrathiafulvalenerelated derivatives. The newly prepared compounds show close to optimal bond length alternation values for maximizing the first molecular hyperpolarizability; and one of them displays the highest mu beta(0) value ever reported for a dithiafulvene-based NLO-phore. The first example of a dithiafulvenylmethylene transfer reaction is also reported.