The characterization of a polyclonal antibody produced via immunization with an [Os(bpy)(2)dcbpy] hapten is described. Bpy is 2,2'-bipyridine and dcbpy is 2,2'-bipyridine-4,4'-dicarboxylic acid. The cross-reactivity of the antibody for the Ru(II) analogue of the hapten was also investigated. Large increases in the emission and luminescent lifetime of a series of Os and Ru complexes were observed on binding of the antibody. Association equilibrium constants were derived from luminescence titration data and were found to be 5.6 x 10(8) and 5.0 x 10(8)M(-1) for [Os(bpy)(2)dcbpy] and [Ru(bpy)(2)dcbpy], respectively. Spectroscopic changes were likely due to the exclusion of H(2)O from the complex/antibody binding cleft and blocking of vibrational relaxation pathways of the Os/Ru excited state. D(2)O/H(2)O experiments confirmed that the antibody protected approx. 82% of [Os(bpy)(2)dcbpy] and 80% of [Ru(bpy)(2)dcbpy] from excited state deactivation by the aqueous solvent.
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