Fluorescence Quenching of Centrosymmetric Acridinedione Derivatives by Alcohols: The Role of Hydrogen Bonds and Their Clustering in Symmetry Breaking Charge Transfer.

Fluorescence quenching of 3,3,11,11-tetramethyl-8,16-diphenyl-3,4,8,10,11,12,13,16-octahydroacridino[4,3-c]acridine-1,9(2H,5H)dione in liquid mixtures of methanol and acetonitrile have been studied using fluorescence spectroscopy methods. The results obtained are interpreted in terms of nonradiative deactivation of the excited state of the fluorophore due to interaction with a protic solvent. A theoretical analysis of experimental data was carried out, its results were compared with data obtained previously in similar studies in mixtures of methanol and dimethylformamide. The values of a number of model parameters were determined, in particular, the rate constant for the formation of "fluorophore–methanol cluster" complexes and the equilibrium constant of this reaction. The mechanisms of the influence of the aprotic cosolvent on the cluster structure of the mixture and the quantum yield of fluorescence have been analyzed. [ABSTRACT FROM AUTHOR]