Specific solvent effects of linear alcohols on the emission spectrum and the excited state decay of tris(2,2'-bipyridyl) ruthenium(II)

This study aims at a quantitative extraction of specific solvent effects of hydroxylic solvents on the non-radiative decay of tris(2,2'-bipyridyl) ruthenium(II). For this purpose the emission spectra, quantum yields and excited state lifetimes of the dye were measured in a series of monovalent linear alcohols. Separation of the non-radiative decay via the energy gap was achieved by evaluating the temperature dependence of quantum yields to account for temperature-activated transitions. The parameters determining the shapes of the emission spectra were calculated by a modified Franck-Condon analysis including the anharmonic Morse potential, and correlated with the non-radiative rate with the help of the energy gap law. The specific effects of hydroxylic solvents were finally obtained by comparison with the well-known behavior in non-hydroxylic solvents, and interpreted with the help of the energy gap law theory.