Synthesis and nonlinear optical properties of a series of azo chromophore functionalized alkoxysilanes

A series of azo chromophores based on benzene and thiazole moieties as conjugating bridges were synthesized and then reacted with 3-isocyanatopropyltriethoxysilane (ICTES) to give various alkoxysilane dyes. Their structures were confirmed by elemental analysis, 1H NMR, FTIR, and UV–visible spectra; thermogravimetric analysis showed that the compounds displayed high thermal stability. The alkoxysilane dyes had very good solubility in common solvents and their nonlinear optical (NLO) activities were evaluated solvatochromically. The results indicate that the thiazole moiety on the electron acceptor side can significantly enhance molecular hyperpolarizability due to its lower aromatic delocalization energy and auxiliary electron-withdrawing ability.