Determination of reorganization energy of fluorenone and 4-hydroxyfluorenone in neat and binary solvent mixtures

Steady-state absorption and fluorescence measurements of fluorenone and 4-hydroxyfluorenone in neat and binary solvent mixtures were used to explore the reorganization energy in liquid system. The results of spectroscopic measurements were used to calculate, according to Marcus theory, the outer-sphere solvent reorganization energy, lambda(0), and the internal molecular reorganization energy, lambda(in). Preferential solvation of fluorenone and 4-hydroxyfluorenone in binary solvent mixtures has been studied by monitoring the outer-sphere solvent reorganization energy. In cyclohexane-tetrahydrofuran mixtures, the deviation from linearity in the lambda(0) versus the solution polarity is due to non-specific dipolar solvent-solute interactions. For cyclohexane-ethanol binary mixtures, both non-specific and specific (hydrogen bond) interactions contribute to the observed changes.