Preparation and release behaviour of the inclusion complexes of phenylethanol with β‐cyclodextrin

Abstract

AbstractThe formation of the inclusion complexes between two phenylethanol isomers [1‐phenylethanol (1‐PE) and 2‐PE)] and three cyclodextrins namely α‐cyclodextrin (α‐CD), β‐cyclodextrin (β‐CD) and HP‐β‐cyclodextrin (HP‐β‐CD) was studied. Phase‐solubility studies showed the two isomers formed 1:1 stoichiometric inclusion complexes with these cyclodextrins and the aqueous solubility of 1‐PE and 2‐PE significantly increased with increasing the cyclodextrin concentration. In this study, β‐CD was chosen as a host molecule, and solid inclusion complexes of β‐CD with two phenylethanol isomers were prepared via the co‐precipitation method for the enhancement of their thermal stability and sustained release. The presence of the two isomers in the inclusion complexes was confirmed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H‐NMR) spectra. X‐ray powder diffraction (XRD) results indicated new crystalline phases for the inclusion complexes. Differential scanning calorimetry (DSC) studies for the inclusion complexes have also shown the formation of supramolecular inclusion complexes between β‐CD and the two isomers. Thermogravimetric analysis (TGA) results demonstrated that the thermal stability of the two isomers was increased as a result of the formation of the inclusion complexation with β‐CD. The release study suggested that β‐CD provided protection for 1‐PE and 2‐PE against evaporation, and 1‐PE in the inclusion complex had a lower release rate than that of 2‐PE. The results have been confirmed with PM3 and B3LYP/6‐31G(d) calculation. It indicates that β‐CD is a proper wall material for increasing thermal stability and the controlled release of 1‐PE and 2‐PE. Copyright © 2015 John Wiley & Sons, Ltd.