Spectrophotometric and electrochemical quantification of the host–guest interaction of tenoxicam and β-CD in aqueous solution at different pH values

Abstract

This work dealt with the spectrophotometric and electrochemical determination of the thermodynamic formation constants, Kf, of the host–guest inclusion complex between diverse tenoxicam species in aqueous solution, Tenox́, and β-cyclodextrin (β-CD) namely: β-CD-H2Tenox+, β-CD-HTenox(z) and β-CD-Tenox−. It was found that it is possible to form the said inclusion complex regardless of the nature of the tenoxicam chemical species and that for each case, similar values of Kf were found from both experimental techniques. Moreover, the values of the Tenox’s acidity constants are also reported. From all these estimated thermodynamic equilibrium constants, the 3D distribution diagram for the different species of the Tenox in the space molar fraction-[β-CD]-pH was constructed.