Synthesis of phenyltetraene chromophores-based hybrid materials for large nonlinear optical activity

•Two new phenyltetraene-based chromophores with alkylthio group were synthesized.•Inorganic–organic hybrid films are prepared through sol–gel process.•Incorporation of alkylthio group effectively improves the nonlinear optical property.

Two new chromophores, CLDS1 and CLDS2, based on a similar D–π–A structure as the phenyltetraene chromophore CLD, but with an alkylthio group perpendicular to the direction of the long molecular axis as isolation spacer were synthesized. Through a urethane forming reaction between 3-isocyanatopropyltriethoxysilane (ICTES) and chromophores, the alkoxysilane dyes were synthesized. Subsequently, a series of transparent and homogeneous inorganic-organic hybrid films were prepared via a sol–gel process of the alkoxysilane dye with triethoxyvinylsilane. The molecular structures of the resultants were confirmed by 1H NMR, FTIR and UV–visible spectra. After electric poling, the nonlinear optical coefficients (d33) of the hybrid films F-CLDS1 and F-CLDS2 were determined to be 104.54 and 98.17 pm V−1, respectively, which are almost 3 times the d33 value of hybrid film containing CLD (37.78 pm V−1), indicating that the incorporation of alkylthio group can efficiently improve the macroscopic optical nonlinearities of hybrid materials.