Synthesis and characterization of an alkoxysilane dye for nonlinear optical applications

In order to achieve organic-inorganic hybrid nonlinear optical (NLO) materials with a highly NLO active chromophore covalently bonded into silica networks, an alkoxysilane dye was synthesized from 3-isocyanatopropyl triethoxysilane (ICTES) and NLO active dye 4-nitro-4′-hydroxy-azobenzene (NHA) by a nucleophilic addition reaction. This dye based on a nitro group as an acceptor end of a donor-π-bridge-acceptor chromophore and a hydroxy as the donor end, has a large βμ value measured by solvatochromic method. Compared with C.I. Disperse Red 1, it displayed better transparency and a higher melting point. The resulting products were highly soluble in aprotic polar solvents such as DMF, DMSO, and THF, etc. Molecular structural characterization for the dye (NHA) and alkoxysilane dye (ICTES-NHA) was investigated by elemental analysis, 1H NMR, FTIR, UV-visible spectra and differential scanning calorimetry (DSC).