Synthesis and second order nonlinear optical properties of new chromophores containing 1,3,4-oxadiazole and thiophene rings

We report the synthesis and physico-chemical characterization, including molecular second order nonlinear optical properties by the EFISH technique, of three new heterocycle based push-pull chromophores. Two chromophores contain the five membered 1,3,4-oxadiazole ring, the third a thiophene ring. The chromophores also contain azo or stilbene bridges between conjugated aromatic rings and are functionalized for covalent incorporation into polymer chains. The maximum observed mu(g)beta is 1350 x 10(-48) esu for the thiophene chromophore in conditions far from resonance enhancement (fundamental laser wavelength 1.907 mum). The crystal structure of one oxadiazole chromophore is also discussed.