Solvent Effects on the Fluorescence of Some π-Electron Systems Naphthylamine and Naphthol

The enhancement or quenching of fluorescence intensity of naphthylamines and naphthol caused by hydrogen bonding with acetic acid esters or pyridine has been measured. By means of detailed analyses of the experimental results, it has been established that the shift of hydrogen bonding equilbrium toward the side of association is realized during the lifetime of excited state. The cause of the shift has been interpreted on the basis of the theory of electron migration, and an evidence supporting the interpretation has been provided by measuring the solvent shift of fluorescence spectra. The mechanism of the fluorescence quenching has been discussed as due to the delocalization of π-electrons through the hydrogen bond.