Inclusion complexes of fluconazole with β-cyclodextrin and 2-hydroxypropyl-β-cyclodextrin in aqueous solution: preparation, characterization and a structural insight

Inclusion complexes of fluconazole (HFlu) with β-cyclodextrin (β-CD) and hydroxypropyl- β-cyclodextrin (HP-β-CD) had been prepared by the coprecipitation method. The 1:1 stoichiometry of complexation for both inclusion complexes was achieved in the binary system by phase solubility and fluorimetric study. The inclusion complexes were also characterized by DSC-TGA analyses and ESI–MS spectra. The molecular assemblies were proposed that a triazolyl ring of HFlu was inserted into the narrower end of the CD cavity and the 2, 4-difluorophenyl ring into the wider end to generate 1-D chain structure on the basis of physical characters. The comparative work indicated that the higher stability was obviously observed for HFlu-HP-β-CD than for HFlu-β-CD, and provided a crucial clue to find out the dependency: cavity size, van der Waals and hydrophobic interactions as well as hydrogen bonding.