Mechanism for the Photochemical Production of Superoxide by Quinacrine

Transient absorption spectroscopy has been used to elucidate the UV-A induced 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 electron formation at this excitation wavelength is determined to be in the range of 0.20−0.40. These results provide a simple mechanism that accounts for the generation of superoxide (O 2 - ) following UV excitation of quinacrine in aqueous solution.