Luminescent pH sensor of a novel imidazole-containing hexanuclear Ru(II) polypyridyl complex.

Feixiang Cheng, Ning Tang, Jishu Chen, Guang Chen

Index: Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 114 , 159-63, (2013)

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Abstract

Hexapodal ligand H6L containing imidazole rings has been prepared by the reaction of 1,10-phenanthroline-5,6-dione with 1,2,3,4,5,6-hexakis[(3-formylphenoxy)methyl]benzene. The Ru(II) polypyridyl complex [{Ru(bpy)2}6(μ6-H6L)](PF6)12 (bpy=2,2'-bipyridine) has been synthesized by the reaction of Ru(bpy)2Cl2·2H2O with ligand H6L. The pH effects on the UV-vis absorption and emission spectra of the complex have been studied. The ground- and excited-state ionization constants of the acid-base equilibria have been calculated according to the absorbance and emission data. The complex acts as an off-on-off luminescent pH sensor through two successive deprotonation processes of imidazole rings, with a maximum on-off ratio of 5 in buffer solution. Copyright © 2013 Elsevier B.V. All rights reserved.