MAGNETIC MODULATION OF EXCIPLEX FLUORESCENCE OF PYRENE SOLUTIONS WITHEXCESS OF AZACROWN ETHER IN THE PRESENCE OF IONS OF ALKALINE AND ALKALINE-EARTH METALS

In photoexcited polar pyrene solutions with excess of phenylaza-15-cro wn-5 serving as a donor an intermolecular electron transfer takes plac e which produces radical-ion pairs whose recombination gives rise to a fluorescent exciplex. Virtually no charge exchange between crown ethe r molecules and their radical-cations is observed in this process. The magnetic effect detected by changes in fluorescence reduces upon addi tion of diamagnetic lithium and calcium ions to the exciplex system, w hich is assigned to formation of paramagnetic complexes.