Synthesis, characterization, and oxygen sensing properties of Ru(II) complex covalently grafted to mesoporous MCM-41

Novel oxygen sensing materials consisting of [Ru(Bphen)2bpy]2+ (Bphen=4,7-diphenyl-1,10-phenanthroline, bpy=2,2′-bipyridyl) portion covalently grafted to the backbones of the ordered functionalized mesoporous MCM-41 are synthesized by co-condensation of tetraethoxysilane (TEOS) and the functionalized Ru(II) complex [Ru(Bphen)2Bpy-Si]2+ using surfactant cetyltrimethylammoniumbromide (CTAB) as template. The Bpy-Si was used as not only one of the precursors of the sol-gel process but also the second ligand of Ru(Bphen)2Cl2·2H2O complex to prepare the functionalized mesoporous materials for oxygen sensors. Dye leaching shortcoming is overcome due to the Si-C bonds. The derivative mesoporous oxygen sensing materials are characterized by Fourier transform infrared (FT-IR), small angle X-ray diffraction (SAXRD), luminescence intensity quenching Stern-Volmer plots, and excited-state decay analysis. The mesoporous materials show higher sensitivity to the O2 concentration in N2 (I0/I100=23.2) and shorter response time (1.2 s) in comparison with those based on sol-gel method. When the concentration of oxygen is 10%, the luminescence intensity of the oxygen sensor can be quenched by 89.9%, suggesting that it is highly sensing at low concentration of oxygen.