Study of inclusion complex formation between tropaeolin OO and β-cyclodextrin by spectrophotometry and Infrared spectroscopy

The mechanism of the inclusion of tropaeolin OO (TPOO) and β-cyclodextrin (β-CD) has been studied by spectrophotometry. The inclusion depth of the guest molecule in the host molecule was demonstrated by infrared spectrometry. Effect of the pH, concentrations of β-CD, solvents and ionic strength on the inclusion of TPOO and β-CD were examined. The result showed that TPOO reacts with β-CD to form a 1:1 host–guest complex with an apparent formation constant of 1.50 × 103 l mol−1. The thermodynamic parameters of inclusion reaction, ΔG°, ΔH° and ΔS° were obtained.