Inclusion complexes of water-soluble calix[n]arenes with quercetin: preparation, characterization, water solubility, and antioxidant features

This study focuses on the construction of two new inclusion complexes of quercetin with p-sulfonatocalix[4]arene-tetracarboxylic acid and/or p-sulfonatocalix[8]arene-octacarboxylic acid, so that the drug gets soluble in an aqueous media. The structures of the inclusion complexes have been analyzed through FT-IR, NMR and UV–Vis spectroscopy. Evidences indicate that the π–π interaction and hydrogen bonding involve in the inclusion complexes of water-soluble calixarenes (Clx4 and Clx8) with quercetin. The associating constants and stoichiometry of the inclusion complexes constructed between p-sulfonatocalix[n]arene-carboxylic acids (Clx4 and Clx8) and quercetin have been also estimated. In addition, the antioxidant behaviors of the inclusion complexes have been investigated. Graphical abstract: [Figure not available: see fulltext.].