INFLUENCE OF ELECTRON-DONOR SUBSTITUENTS ON THE LUMINESCENCE BEHAVIOROF A 2-AMINOAZINE

A comparative luminescence study of 5 related 2-aminoazines indicates that there is a dependence of emission polarization and other photophy sical parameters upon the extent of charge transfer in the lowest exci ted singlet and triplet states, The phosphorescence emission polarizat ion is shown to increase from - 0.1 to + 0.28 for substituents with an increasing tendency toward electron donation, while only minor change s occur in the triplet state energy. An electron donor substituent inc reases intersystem crossing and the phosphorescence yield, which is ac companied by a decreasing fluorescence yield, and a decreasing phospho rescence lifetime.