A new synthetic route to sol-gel materials containing nonlinear optical chromophores

Network formation using chlorotris(diethylamino)silane [ClSi(NEt 2)3], tetrakis(dimethylamino)silane [Si(NMe2) 4], and tetrakis(diethylamino)tin [Sn(NEt2)4], and NLO-active chromophore was investigated to yield inorganic-organic hybrid materials for 2nd-order nonlinear optics. In contrast to hybrids obtained from Si(NEt2)4, those prepared from ClSi(NEt 2)3 and Sn(NEt2)4 were insoluble even in high boiling solvents. Facile hydrolysis of the NLO-active dye was found to occur in these hybrids due to the catalysis of HCl and the high reactivity for ClSi(NEt2)3 and Sn(NEt2)4 respectively. Due to the insolubility of the networks, it was not possible to determine if the dye present in these networks was physically trapped or covalently bound to the inorganic matrix. It was observed that the method used for the hydrolysis of M--NR2 bond played an important role in the stability of the Si--OR bond for hybrids prepared from Si(NMe 2)4 and Sn(NEt2)4.