A Synthetic Tetra‐Amide Macrocycle for Anion Recognition at Molecular Level

Abstract

AbstractAn engineered tetra‐amide macrocycle is presented, and its conformation and anion recognition properties are investigated. The tetra‐amide macrocycle 1, containing the m‐amino benzoic acid, 1,3‐benzenedicarboxylic acid and m‐xylenedinediamine adopts an envelope‐like conformation in solid‐state, where the m‐xylenedinediamine ring is perpendicular with the molecular plain. The tetra‐amide macrocycle 1 is able to bind anions such as halides, sulphate and phosphate in DMSO (dimethyl sulphoxide) solution. The stabilities of the fluoride (2.6×103 M−1) and chloride (5.6×102 M−1) complexes of 1 in DMSO is higher than that of bromide (66 M−1) and iodide (52 M−1). SO42− complexes of 1 in DMSO is more stable than the HSO4−, NO3− and H2PO4− complexes. Using this information, a quantitative evaluation of the stability of the 1 : 1 complex of 1, for which overall binding energy in the order −123.98 kcal/mol for SO42−was calculated. The strong binding affinity of the tetra‐amide macrocycle 1 toward the SO42− ion can be explained on the basis of non‐covalant interaction like ion−dipole interaction, hydrogen bonding interaction and size selectivity.