A systematic study of the reaction of 1-chloromethyl-4-(2-trichlorosilylethyl)-benzene (coupling agent) with the surface Si-OH groups of glass for times from 15 min to 48 h, followed by stilbazole chromophore precursor deposition/quaternization, is reported. Second harmonic generation characteristics of these thin film materials indicate that a 15 min coupling agent reaction attains approximately 65% of full surface coverage (based on chi(zzz)(2)) of benzylic chloride moieties, but that 24 h is the optimal time for maximum coverage. The surface-anchored chromophoric chloride salts in such materials undergo facile ion exchange with iodide, p-aminobenzenesulphonate, and ethyl orange, leading to enhancements in chi(zzz)(2) of up to 50%.