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.