On the quenching of MLCT luminescence by amines: The effect of nanoaggregation in the decrease of the reorganization energy

The MLCT luminescence quenching of pyRe(CO)3bpy+ and/or the polymer {[(vpy)2-vpyRe(CO)3bpy]CF3SO3}n–200 by amines proceeds via an electron transfer reaction which produces amine radical cations and pyReI(CO)3(bpy)/–ReI(CO)3(bpy), respectively. The quenching follows a typical Stern–Volmer kinetics for both pyRe(CO)3bpy+ and {[(vpy)2-vpyRe(CO)3bpy]CF3SO3}n–200. The observed rate constants for the quenching of the ReI-polymer luminescence by amines show “vestiges” of the inverted effect predicted by Marcus while the quenching of pyRe(CO)3bpy+ luminescence follow the Rehm–Weller type of behavior. The lower value obtained for the total reorganization energy of the ReI-polymer than that for pyRe(CO)3bpy+ is rationalized in terms of the retarded solvent motions inside the nanoaggregates formed by the ReI-polymer in acetonitrile solutions.