The Photoassociation of 1- and 2-Acetylanthracenes with Methanol

Abstract

The effect of small amounts of methanol (≤0.34 mol dm−3) upon the absorption and fluorescence spectra of 1- and 2-acetylanthracenes in hexane was investigated. While the formation of a 1 : 1 hydrogen-bonded complex in the ground state was revealed by the isosbestic points of the absorption spectra, the change in the fluorescence spectra was indicative of the photogeneration of a highly associated complex which includes at least two alcohol molecules. On the assumption that the excited 1 : 1 complex further associates with an alcohol molecule, the computer simulation by the least-squares method provided a good fit of the observed concentration dependence of methanol upon the fluorescence quantum yield. The photokinetic parameters and the thermodynamic quantities were evaluated from the parameter values.