Temperature dependence and related properties of beta-cyclodextrin inclusion effects on the fluorescence intensities of hydroxycoumarin-based pesticides

The temperature dependence of the enhanced fluorescence intensities of warfarin and coumachlor complexed with β-cyclodextrin was investigated in a temperature range of 15–40°C. From these results, equilibrium constants at six different temperatures (15, 20, 25, 30, 35, 40°C) and the standard-enthalpy and -entropy changes for the complexation of β-cyclodextrin with these pesticides were estimated by means of the stoichiometric and thermodynamic analysis methods. Characterization of the fluorescence-enhancing effect of β-cyclodextrin on these pesticides was done on the basis of equilibrium and thermodynamic properties of the relevant inclusion complexes.