Evidence of anion-induced dimerization of a squaramide-based host in protic solvents

The combination of squaramide units with tetraalkylammonium groups leads two hosts that bind distinctively dianions in water-ethanol mixtures. The formation of complexes of 2 : 1 stoichiometry with host 2 was supported by ITC, fluorescence, and H-1 NMR data.