Abstract
Photophysics of [Ru(bpy)(CN)4]2− (bpy=2,2′-bipyridine) in CH3OH, CH3OD, CD3OD, and CH3OH/C2H5OH and CH3OD/C2H5OD solvent mixtures has been investigated by steady state and time-resolved techniques at various temperatures. The Franck–Condon analysis of the emission spectra observed between 80 and 165K indicates similar and significant decrease in energy of the luminescent excited state (E0–0) and a small difference in the increasing solvent reorganizational energies for solvent mixtures of CH3OH/C2H5OH and CH3OD/C2H5OD, respectively. The rate of non-radiative (knr) and radiative decay (kphos) to the ground state and the parameters of thermally activated deactivation pathways (A4th, ΔE4th and Add, ΔEdd) have been determined between 250 and 330K in CH3OH, CH3OD and CD3OD. The rate of phosphorescence and apparent activation energy of temperature dependent deactivations are not sensitive to the replacement of H to D, while the knr and the pre-exponential factor of thermally activated decay through the 4thMLCT state decreases with the replacement of H to D in the OH group of the solvent. The deuteriation of the methyl group in the solvent results in a small change of knr. The results provide further experimental evidence of the hydrogen-bond determined specific solvent–solute interaction playing important role in the decay of the lowest energy MLCT excited state of [Ru(LL)(CN)4]2− complexes.
Published Version
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