Chalcogens as electron donors for selected nonlinear optic phores

Abstract

Three different heteroaromatic charge transfer chromophores, e.g. donor(D)–acceptor(A)-substituted thieno [3,2-b] thiophenes 3 and 4, D-substituted thieno [2,3-c] pyridinium salts 7 and 2-(2′-thienyl)pyridinium salts 10 have been prepared. Alkylchalcogenic ethers were used as D-groups. The molecular first hyperpolarizabilities β were determined by the EFISH method in the case of 3 and 4 and by the HRS method in the case of the ionic compounds 7 and 10. Substitution of the ether oxygen atom by sulfur increases markedly the β value which is not further increased by the higher chalcogens selenium and tellurium.