Mesoporous MCM-41 embeded with Ru(II)-based chemosensor: Preparation, characterization, and emission variation towards pH

In this article, a pH sensing mesoporous MCM-41 material containing covalently bonded Ru(II) complex in the silicate network was prepared and named as Ru-MCM-41. The emission signal shows a tendency to decrease upon increasing pH values. The luminescent pH sensor can be explained by the protonation and deprotonation of the PIP ligand (PIP=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline) and the fact that the mesoporousity of the MCM-41 matrix favors the -OH that diffused to the complex, resulting in quick emission quenching. It also shows a slight sensitivity towards dissolved molecular oxygen and varying temperatures, which, however, may not be too troublesome for actual applications. The sensing mechanism is also investigated. (C) 2014 Elsevier B.V. All rights reserved.