PROTON-TRANSFER IN THE INTERMOLECULAR VS INTRAMOLECULAR QUENCHING OF NAPHTHOL FLUORESCENCE BY AMINES

'Charge-transfer' quenching of naphthols by amines can occur via either proton transfer or electron transfer. To gain insight into the quenching mechanism, the room temperature photophysics of 2-naphthol (N2) in the presence of a trialkylamine was compared with that of 2-methoxynaphthalene (N2M) and of an intramolecular equivalent, 1-[(dimethylamino)-methyl]-2-naphthol (IDMN2). To maintain structural analogy, dimethylbenzylamine (DMBA) was used as the quencher. Comparison of steady-state and time-resolved fluorescence for both intermolecular and intramolecular cases leads to the conclusion that the major quenching pathway involves proton transfer.