Structure and stoichiometry of resorcinarene solvates as host–guest complexes – NMR, X-ray and thermoanalytical studies

Abstract

Controlled release of a guest from inclusion host–guest complexes is an important aspect of design and synthesis of advanced materials for sensing, purification, chromatography, and storage of wide variety of molecules. In this work, host–guest complexes of C-methylcalix[4]resorcinarene (RES1) and C-undecylcalix[4]resorcinarene (RES2) with four solvents were examined by NMR, X-ray and thermoanalytical techniques in order to compare their stoichiometries, solvent effects, the role of water during solubilization/complexation process. The phenomena of poor solubility of some resorcinarenes in dry solvents versus their good solubility in wet solvents is explained on example of resorcinarene/dioxane/water complex. An asymmetric unit contains RES1 macrocycle in C2v symmetry which adopts a boat-like conformation and RES1 is a rccc isomer with four axial methyl groups. Water is a molecular linker that organizes the whole network in RES1·2dioxane·3H2O solvate.