A comprehensive molecular insight into host-guest interaction of Phenanthrene with native and ionic liquid modified β-cyclodextrins: Preparation and characterization in aqueous medium and solid state

Abstract The inclusion complexes of Phenanthrene with native βCD and ionic liquid modified βCD were prepared and investigated in both solid and solution states. The formation of the inclusion complexes were successfully monitored by FTIR, TGA, DSC, 1D 1H NMR, 2D NOESY NMR and UV–vis spectroscopy. The results revealed that Phenanthrene formed 1:1 a stoichiometry ratio for both host-guest inclusion complexes with an apparent formation constant of 239.7 M-1 for native β-cyclodextrin, which was higher than ionic liquid modified β-cyclodextrin (14.9 M-1). The NMR studies showed that Phenanthrene penetrated into the cavity of both cyclodextrins (CDs) from the more accessible wider side. For βCD, Phenanthrene displayed one mode of binding, i.e., formation of an inclusion complex. Meanwhile, ionic liquid modified β-cyclodextrin demonstrated two modes of binding, i.e. inclusion in the CD cavities and interaction with the outer surface of the CD molecules, mainly near the ionic liquid (IL) group.