Thermodynamic parameters and quantum chemical calculations of complex formation between rutin and 2-hydroxypropyl-β-cyclodextrin in water-ethanol solvents

The thermodynamic parameters of the complexation between rutin (Rut) and hydroxypropyl-beta-cyclodex trin (HP-beta-CD) in water-ethanol solvents (lgK, Delta H-r, Delta(r)G, T Delta S-r) were calculated from isothermal titration calorimetry. A decrease in the stability of the complex was observed with an increase in EtOH concentration in the solvent, and the change in the Gibbs energy of the complex formation is controlled by the enthalpy factor. The increase of the entropy contribution to the change in the Gibbs energy of the [Rut subset of HP-beta-CD] complex formation reaction is probably caused by an increase in the number of free water molecules as a result of the Rut and HP-beta-CD desolvation in aqueous-ethanol solvents. The effect of different solvents such as water and ethanol was included via the analytical linearized Poisson-Boltzmann (ALPB) model, which was implemented in the GFN2-xTB code. The effect of solvent on the rutin's ability to interact with HP-beta-CD is decreasing in the following order: water > ethanol. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The thermodynamic parameters of the complexation between rutin and hydroxypropyl-beta-cyclodextrin in water-ethanol solvents were investigated. The stability of the complex decreased with increasing ethanol concentration, and the change in Gibbs energy was primarily influenced by the enthalpy factor. The effect of different solvents showed that water had a greater impact on the interaction between rutin and hydroxypropyl-beta-cyclodextrin.