Spectroscopic Study on Interaction of β ‐Cyclodextrin with Triprolidine Hydrochloride

The complexation of triprolidine hydrochloride (TRP) and β ‐cyclodextrin ( β ‐CD) in deuterium oxide was investigated by 400 MHz 1 H NMR spectroscopy. The 800 MHz 2D ROESY data revealed that two 1:1 and one 2:1 β ‐CD‐TRP inclusion complexes were formed. Both aromatic moieties ( p ‐tolyl and pyridyl ring) has entered into the β ‐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 β ‐CD‐triprolidine hydrochloride in solution.