PHOTOCHEMICAL EXPULSION OF IODIDE FROM THE 1-IODOANTHRAQUINONE RADICAL-ANION

The electrochemical reduction of 1-iodoanthraquinone in acetonitrile solvent, in the presence of tetrabutylammonium perchlorate, at electrodes irradiated with light corresponding to an absorption band of the 1-iodoanthraquinone radical anion, is shown to produce the radical anion of anthraquinone via a mixed ECE/DISP1 mechanism. The rate of explusion of the iodide anion is quantified and excitation at 565 nm is approximately 7.5 times faster in this respect than at 417 nm. Novel in situ spectrofluorimetric electrochemical experiments reveal emission from two different excited states, and the causes of the contrasting rates of iodide loss are discussed.