Polyenic nonlinear optic (NLO)-phores with a proaromatic 1,4-dithiafulvene electron donor and the littleexplored 1,1,3-tricyano-2-phenylpropene acceptor have been synthesized. Their configurational andconformational features, ground state polarization, and linear and nonlinear optical properties have beendetermined experimentally and theoretically, and the results are compared to those of tetrathiafulvalene-related derivatives. The newly prepared compounds show close to optimal bond length alternation valuesfor maximizing the first molecular hyperpolarizability, and one of them displays the highest
0 valueever reported for a dithiafulvene-based NLO-phore. The first example of a dithiafulvenylmethylene transferreaction is also reported.