Binding and selectivity aspects of an expanded azamacrocycle for anions

An expanded azamacrocycle was studied for its anion binding ability towards chloride, bromide, iodide, sulfate, nitrate and perchlorate by 1H NMR titrations in D2O at pH 1.7. The results suggest that the ligand shows the moderate selectivity for sulfate in solution. X-ray diffraction analysis of the perchlorate complex of L suggests that the ligand interacts anions from both sides forming a ditopic complex with strong NH···O bonds. In the packing diagram, the macrocycles and external perchlorates are alternatively linked through hydrogen bonding to form a 1D chain.