The Quenching Action of Benzoic Acid and Methyl Benzoate on the Fluorescene of Naphthalene Derivatives. II

Publisher Website
Google Scholar
Abstract
The quenching action of benzoic acid on the fluorescence of naphthalene derivatives, for instance, N, N-dimethyl-2-naphthylamine, is phenomenologically ascribed to its dimer. In order to examine its molecular mechanism, absorption and fluorescence spectra have been measured on solutions of N, N-dimethyl-2-naphthylamine with and without benzoic acid, using as a solvent cyclohexane to which various amounts of dioxane or ethyl ether has been added. The quenching action of benzoic acid has also been measured in similar solvents. A good parallelism has been found between the change in the absorption spectra of benzoic acid and the change in the quenching action of benzoic acid when both are examined as functions of the concentration of dioxane or ether. From this finding, and from the more precise analysis of the data described in a previous paper (This Bulletin, 38, 529 (1965)), it has been concluded that the quenching action of benzoic acid may be ascribed to the direct interaction between the fluorescer and the benzoic acid dimer. Further, similar quenching actions have been observed in o-, m- and p-toluic acids, and p-methoxy-bonzoic acid.