Solvent-controlled electron transfer in crystal violet lactone.
Steady-state and picosecond time-resolved emission experiments are used to examine the excited-state charge transfer reaction of crystal violet lactone (CVL) in aprotic solvents. Solvatochromic analysis using a dielectric continuum model suggests dipole moments of 9-12 D for the initially excited (LE) state and ∼24 D for the charge-transfer (CT) state. Intensities of steady-state emission as well as kinetic data provide free energies for the LE → CT reaction that range from +12 kJ/mol in nonpolar solvents to -10 kJ/mol in highly polar solvents at 25 °C. Reaction rates constants, which lie in the range of 10-100 ns(-1) in most solvents, depend on both solvent polarity and solvent friction. In highly polar solvents, rates are correlated to solvation times in a manner that indicates that the reaction is a solvent-controlled electron transfer on an adiabatic potential surface having a modest barrier.
Li
Xiang
X
The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Maroncelli
Mark
M
D004579:Electron Transport; D005840:Gentian Violet / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics
D012997:Solvents; D005840:Gentian Violet; C048923:crystal violet lactone