Effect of two methoxy groups bound to an amino-benzene donor unit for thienyl-di-vinylene bridged EO chromophores

• We report the molecular first hyperpolarizability of a series of EO chromophores.
• Effect of two methoxy groups bound to amino-benzene donor unit was studied.
• Improvements in hyperpolarizability were found for the modified EO chromophores.
• Double intra-molecular hydrogen bonding as a mechanism of improvement was proposed.
• We found an important area of progress in the design of EO chromophores.

We report the molecular first hyperpolarizability (β) and absorption and 1H NMR spectra of electro-optic (EO) chromophores comprised of amino-benzene with two methoxy groups at meta-positions as the donor units, thienyl-di-vinylene as the π-electron bridges, and 2-(dicyanomethylene)-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF), 2-(dicyanomethylene)-3-cyano-4,5-dimethyl-5-trifluoromethyl-2,5-dihydrofuran (CF3-TCF) or 2-(dicyanomethylene)-3-cyano-4-methyl-5-phenyl-5-trifluoromethyl-2,5-dihydrofuran (CF3-phenyl-TCF) as the acceptor units. Improvement in linear and nonlinear optical properties was found in EO chromophores with two methoxy groups compared with benchmark EO chromophores without these groups and EO chromophores with one methoxy group. The data obtained from measurements of hyperpolarizability (β) and absorption and 1H NMR spectra indicate a possible mechanism that can contribute to improvement – double intra-molecular hydrogen bonding.