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

Two new chromophores, CLDS1 and CLDS2, based on a similar D-pi-A structure as the phenyl-tetraene 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 H-1 NMR, FTIR and UV-visible spectra. After electric poling, the nonlinear optical coefficients (d(33)) 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 d(33) 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. (c) 2013 Elsevier Ltd. All rights reserved.