Synthesis, structural characterisation and luminescent anion sensing studies of a Ru(II)polypyridyl complex featuring an aryl urea derivatised 2,2′-bpy auxiliary ligand

The inclusion of a urea functionality into the coordination sphere of a Ru(II)-polypyridyl complex (Ru center dot L-1) resulted in a system that can function as an effective long wavelength emissive fluorescent anion sensor. The MLCT emission of Ru center dot L-1 is sensitive to the binding of acetate, phosphate and pyrophosphate but not fluoride in organic solvent. In addition, Ru center dot L-1 can distinguish between phosphate and pyrophosphate with an emission increase upon binding of H2PO4- (turn on'' sensor) and an emission decrease upon binding of HP2O73- (turn off'' sensor), which occurs via hydrogen bonding to the urea receptor moiety as demonstrated by carrying out NMR titrations as well as by employing [Ru(II)bpy(3)](PF6-)(2) as a model compound that lacks the anion receptor moiety. (C) 2011 Elsevier B.V. All rights reserved.