Spectrofluorimetric Study of the Inclusion Complex of 7-Hydroxymethylnalidixic Acid with γ-Cyclodextrin in Aqueous Solution

Abstract

A fluorimetric study on the spectral characteristics and acid-base behavior of 7-hydroxymethylnalidixic acid has been performed. The host–guest complexation process between γ-cyclodextrin and 7-hydroxymethylnalid ixic acid has also been investigated by fluorescence spectroscopy. Scatchard and Benesi-Hildebr and methods have been applied to determine the stoichiometry of the complex, and a 1:1 stoichiometric ratio has been established. A K₁ = 118 ± 25 M⁻¹ formation constant has been calculated for the inclusion complex, by using the changes produced on the fluorescence of 7-hydroxymethylnalid ixic acid, when it is included on the hydrophobic cyclodextrin cavity. A fluorimetric method of determination of 7-hydroxymethylnalid ixic acid, in γ-cyclodextrin aqueous solution, has been proposed. The analytical parameters and detection and quantification limits of the method have been determined.