Oxygen-sensing materials based on ruthenium(II) complex covalently assembled mesoporous MSU-3 silica

Novel oxygen-sensing materials consisted of [Ru(Phen)3]2+ portion covalently grafted to the functionalized mesoporous MSU-3 backbones are prepared by co-condensation of tetraethoxysilane and the functionalized Ru(II) complex [Ru(Phen)2Phen-Si]2+ (Phen = 1,10-phenanthroline, Phen-Si = 2-[4′-{3-(triethoxysilyl)propyl}phenyl] imidazo [4,5-f]-1,10-phenanthroline) in the presence of Pluronic P123 surfactant as templates. For comparison purpose, the second oxygen-sensing materials in which [Ru(Phen)3]2+ is conventionally physically incorporated into the matrix are also prepared. The obtained oxygen-sensing materials are characterized by Fourier transform infrared, small angle X-ray diffraction, scanning electron microscopy, nitrogen adsorption/desorption analysis, and luminescence intensity quenching Stern–Volmer plots. The functionalized mesoporous sensing materials are found to be highly sensitive to O2. The results also reveal that the covalently grafted sample exhibits better reversibility and higher photochemical stability than the physically incorporated sample since these Ru(II) molecules are strongly covalently grafted to the Si–O network via the CH2–Si bonds.