Large quadratic hyperpolarizabilities with donor-acceptor polyenes functionalized with strong donors. Comparison with donor-acceptor diphenylpolyenes Original Research Article

Donor-acceptor polyenes and carotenoids of defined and increasing length, bearing electron-donating ferrocene or julolidine moieties, and formyl or dicyanovinyl electron-withdrawing end groups have been prepared in order to achieve enhanced quadratic optical nonlinearities. The variation of their quadratic hyperpolarizability β in solution was investigated using the electric field induced second harmonic (EFISH) generation technique, and was compared to the behavior of two series of soluble push-pull diphenylpolyenes.