Beyond Size Complementary Factors in Anion-Tetralactam Macrocycle Complexes: From Intrinsic Gas-Phase to Solvent-Predicted Stabilities

Abstract

The gas-phase affinities of different types of anions X- (halogen anions, oxoanions, and hydrogenated anions) toward a model tetralactam-based macrocycle receptor (1), defined in terms of stability of an anion-receptor complex (1 + X-) against its disintegration, were evaluated by dissociation studies using a mass spectrometry-based methodology and supported by theoretical calculations (density functional theory-PBEo). The gas-phase complex with Cl- was found to be tailor-made for the macrocycle 1, while 1 + SA(-) (SA(-) = salicylate anion) and 1 + HSO4- were the weakest ones. Other complexes displayed a relatively low-stability dispersion (<1.2 kcal.mol(-1)). The 1/epsilon(r) approach of the electrostatic contribution trends in a dimethyl sulfoxide solvent from the gas-phase binding energy partition High deformation energy and differences in solvation energies were suggested predicted and experimental stabilities of 1 + F- and 1 + H2PO4- complexes.