Spectroscopic study on interaction of β-cyclodextrin with triprolidine hydrochloride

The complexation of triprolidine hydrochloride (TRP) and beta-cyclodextrin (beta-CD) in deuterium oxide was investigated by 400 MHz H-1 NMR spectroscopy. The 800 MHz 2D ROESY data revealed that two 1 : 1 and one 2 : 1 beta-CD-TRP inclusion complexes were formed. Both aromatic moieties (p-tolyl and pyridyl ring) has entered into the beta-CD cavity, confirming the existence of two different equilibria for 1 : 1 inclusion complexes in which p-tolyl ring of the guest is more tightly held by the host cavity. The ROE intermolecular interactions provided the plausible structures of these 1 : 1 and 2 : 1 stoichiometric inclusion complexes of beta-CD-triprolidine hydrochloride in solution.