PROTONATION DEPENDENT ELECTRON-TRANSFER IN 2-STYRYLQUINOLINES

The absorption and emission spectra for 4'-substituted-2-trans-styrylq uinoline (X = NMe2, 1; H, 2; CN, 3; NO2, 4) and 4'-N,N-dimethylamino-2 -trans-styrylnaphtalene 5 were studied in various solvents and at vari ous acid concentrations. Monoprotonated or doubly protonated forms of 1 are present depending on the acid concentration. Excited state depro tonation of the doubly protonated form of 1 is observed in aprotic dic hloromethane solvent. This excited state deprotonation process can be prevented by introducing protic methanol to the aprotic solvent media.