Self-assembly oxygen sensing thin film based on a Ru(II) complex covalently grafted to porous anodized alumina oxide (AAO) templates

摘要

A novel functional Ru(bpy)(2)(phen-NH2)(PF6)(2) complex (bpy = bipyridyl, phen-NH2 = 5-amine-1,10-phenanthroline) is covalently bonded to an anodized alumina oxide (AAO) template through a "soft bridge" of 3-glycidoxypropyltrimethoxysilane (GPMS). This can form an oxygen sensor with the structure [Ru(bpy)(2)(phen-NH)/GPMS/AAO]. This oxygen sensing thin film was characterized using scanning electron microscopy (SEM) and fluorescence spectrophotometry. A series of cluster structures were observed on the surface of the AAO, the Ru(bpy)(2)(phen-NH2) fluorophore which was uniformly dispersed. The film proved to have good oxygen quenching properties owing to the great interaction between the fluorophore and molecular oxygen. Finally, a Stern-Volmer plot of the [Ru(bpy)(2)(phen-NH)/GPMS/AAO] thin film shows a good linearity with a fitting parameter R-2 of 0.9948 when the oxygen concentration is 0%-80%, and the sensitivity rises to 10.47, which is 7.5 times greater than that of oxygen sensors based on sol-gel methods. A short response/recovery time of 7 s/15 s was achieved, which is almost 100% faster than that of sol-gel methods with the same fluorophore. When stored in the ambient air of the laboratory, there was no significant drift in intensity after 6 months. These characteristics result in the thin film of [Ru(bpy)(2)(phen-NH)/GPMS/AAO] being a promising candidate for sensitive oxygen sensors.