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The inclusion complexes of β-CD and parecoxib [PRB] in aqueous solution were investigated using 1H NMR spectroscopic study revealed the existence of four different equilibria for 1:1 inclusion complexes in which both the aromatic rings of the guest are tightly held by the host cavity. The NMR spectra of the PRB studied in the presence of β-CD are fully assigned and interpreted by means of COSY spectrum for the unambiguous assignment of guest aromatic ring protons. The parallel interpretation of β-CD chemical shift changes and dipolar contacts, with the aid of 2D ROESY, allows the mode of binding to be established for four possible structures of 1:1 PRB-β-CD inclusion complexes.

A detailed spectroscopic study ( NMR, COSY, ROESY) of complexation of venlafaxine hydrochloride (VEN) with -cyclodextrin (--CD) was carried out in solution. The stoichiometry of the complex was determined to be 1 : 1 and penetration of aromatic ring into -Cyclodextrin cavity was confirmed from primary rim side, with the help of ROESY spectral data. The structure of the venlafaxine hydrochloride--CD complex has been proposed. The association constant was determined to be 234 .

The complexation of triprolidine hydrochloride (TRP) and β-cyclodextrin (β-CD) in deuterium oxide was investigated by 400 MHz 1H 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.

(1)HNMR spectroscopic study in D(2)O of mixtures of D-(-)-chloramphenicol (guest), present in two tautomeric forms in solution, and beta-cyclodextrin (host) revealed the formation of 1:1 inclusion complex in which aromatic ring of the guest is tightly held by the host cavity. There seems no discrimination between the aromatic rings of two tautomers by the host.

A detailed NMR (¹H , COSY, ROESY) spectroscopic study of complexation of enalapril maleate with beta-cyclodextrin was carried out. The ¹H NMR spectrum of enalapril maleate confirmed the existence of cis-trans equilibrium in solution, possibly due to hindered rotation along the amide bond. The cis-trans ratio remained almost the same in the presence of beta-cyclodextrin but in one case it was found significantly different which suggests a catalytic role of beta-cyclodextrin in the isomerization. ¹H NMR titration studies confirmed the formation of an enalapril-beta-cyclodextrin inclusion complex as evidenced by chemical shift variations in the proton resonances of both the host and the guest. The stoichiometry of the complex was determined to be 2:1 (guest: host). The mode of penetration of the guest into the beta-cyclodextrin cavity as well as the structure of the complex were established using ROESY spectroscopy.

A proton magnetic resonance spectroscopic study in D2O of mixtures of fluoxetine hydrochloride (guest) with beta-cyclodextrin (host) revealed the existence of two different equilibria for 1:1 inclusion complexes in which -CF3 substituted ring of the guest is more tightly held by the host cavity. The structures of the two complexes have been proposed which are supported by 2DROESY spectral data. The dissociation constant was also determined.