Mechanism for the photochemical production of superoxide by quinacrine

Transient absorption spectroscopy has been used to elucidate the UV-A induc ed photodynamics of quinacrine. Following excitation of quinacrine in a pH 7.2 buffer solution at 395 nm, the excited molecule ejects an electron into the surrounding aqueous solution. The quantum efficiency for solvated elec tron formation at this excitation wavelength is determined to be in the ran ge of 0.20-0.40. These results provide a simple mechanism that accounts for the generation of superoxide (O-2(-)) following UV excitation of quinacrin e in aqueous solution.