NMR investigations of the inclusion of thyroxine and derivatives in natural cyclodextrins

Thyroxine T4 and its derivatives (T3, T2) are very sparingly soluble in aqu eous solutions even in the form of salts. In the presence of beta or gamma- cyclodextrins and in buffered basic solution, their solubilities are increa sed by inclusion in the cavity. The inclusion of these hormones in cyclodex trins was investigated by H-1-NMR in order to derive the influence of the n umber and position of the iodine atoms, and of the ionization state of the phenol group on the inclusion geometries.