Structural Diversity in the Crystalline Complexes of para-Sulfonato-calix[4]arene with Bipyridinium Derivatives

The solid-state structures of eight complexes between para-sulfonato-calix[4]arene (C4S) and bipyridinium derivatives, 4,4′-bipyridine (BP), 1,2-bis(4-pyridyl)ethane (BPE), and 1,3-bis(4-pyridyl)propane (BPP), have been determined. All the complexes show high degrees of solvation, involving water and ethanol or methanol or acetone. The observed host/guest stoichiometry is determined in part by the nature of the solvent. A wide range of noncovalent interactions are observed in the various complexes, with the dominant interaction being hydrogen bonding and aromatic−aromatic stacking.