Photostability of the inclusion complex of isoamyl4-(Dimethylamino)benzoate with sulfobutylether-β-cyclodextrin

The inclusion complex of isoamyl 4-(Dimethylamino)benzoate (IDB) with sulfobutylether-β-cyclodextrin (SBE-β-CD) was prepared by freeze-drying method. The Benesi-Hildebrand method and Job’s plot showed that the IDB formed 1:2 stoichiometric inclusion complex with SBE-β-CD. The inclusion complex of SBE-β-CD with IDB was characterized by X-ray powder diffractometry (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), nuclear magnetic resonance (1H NMR) and two-dimensional rotational frame Overhauser effect spectroscopy (2D ROESY). The results of 1H NMR and 2D ROESY spectra showed that the hydrophobic group of IDB associated with SBE-β-CD from the wide and narrow side. The solubility and thermal stability of IDB were both improved after formed the inclusion complex. The photodegradation experiment showed that the photolysis ratio of IDB decreased from 9.16% to 2.25% due to the complexation of SBE-β-CD. It could be the potential way to promote its cosmetic application in UVB sunscreen.