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

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.