Self-assembly characterization of the β-cyclodextrin and hydrochlorothiazide system:: NMR, phase solubility, ITC and QELS

Supramolecular self-assembly formed by beta-cyclodextrin (beta-CD) and hydrochlorothiazide (Htz) was characterized in two aspects: (1) Short distance host-guest interactions, by NMR techniques such as H-1 chemical shift, longitudinal relaxation times -T-1, 2D H-1-H-1 nuclear Overhauser spectroscopy, and thermodynamic solubility experiments in which the interaction thermodynamic parameters were calculated for host-guest interactions and (2) Self-assembly of inclusion complex, which was observed in excess of CD by isothermal titration calorimetry and quasi-elastic light scattering. In this work, the self-assembly of Htz and beta-CD occurred above the concentration of approximate to 10(-4) mM. This phenomenon was verified when excess of beta-CD was used in the presence of the higher hydrogen bonding formation molecule as Htz. At lower CD molar ratio the inclusion compound formation is the preferential phenomenon. Thus the Htz seems act as a seeding molecule capable of inducing the self-assembly phenomena, through hydrogen bonding formation between the inclusion compounds.