Conductometric Studies of Formation the Inclusion Complexes of Phenolic Acids with β-Cyclodextrin and 2-HP-β-Cyclodextrin in Aqueous Solutions

An attempt was made to evaluate the possibility of creating and assessing the stability of inclusion complexes of selected phenolic acids [trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) and trans-3-phenylacrylic acid (trans-cinnamic acid)] with β-cyclodextrin and 2-HP-β-cyclodextrin in aqueous solutions in a wide temperature range 283.15 K–313.15 K. On the basis of the values of the limiting molar conductivity (Λ_CDNaDod), calculated from the experimental data, the values of the formation constants and the thermodynamic functions of formation (standard enthalpy, entropy, and Gibs standard enthalpy) of the studied complexes were determined. It has been found that the stability of the studied complexes increases with lowering of the molar mass of cyclodextrin and lowering of the temperature.