EXCITED-STATE DYNAMICS IN THE STRUCTURAL CHARACTERIZATION OF SOLID ALKYLTRIMETHOXYSILANE-DERIVED SOL-GEL FILMS AND GLASSES CONTAINING BOUND OR UNBOUND CHROMOPHORES

A series of alkyltrimethoxysilane-derived sol-gel glasses and films containing included (pyrene) and covalently bound ((1-pyrenylmethyl)trimethoxysilane, 1) fluorescent dopants have been prepared. The structures of these doped sol-gel films are affected by (1) the manner of dopant incorporation into and dispersion throughout the matrix, (2) the local polarity of the dopant, and (3) the curing method. The dopants (pyrene and 1) are well-dispersed throughout the glasses: excimer emission is not observed in the final films. The polarity of the dopant is primarily influenced by the silicon-oxide matrix rather than the identity of the alkyl group in the silane precursor. In the pyrene-doped films, a modest decrease in polarity is observed as the silane alkyl chain length is increased. Corona poling at elevated temperatures during curing results in the highest values of emission anisotropy; dopant molecules in films corona-cured at 60-degrees-C undergo the least amount of rotational diffusion during their excited-state lifetimes.