Synthesis of crescent aromatic oligoamides with preorganized chelating groups and their extraction towards transition metal ions

摘要

Three crescent aromatic oligoamides 1-3 with their backbones rigidified by intramolecular hydrogen bonds were designed and synthesized. The liquid-liquid extraction by these compounds has been investigated using UV-vis spectrometry towards Pb~(2+) picrate and some transition metal picrates including Ag~+ Hg~(2-), Cd~(2+), Zn~(2+), Cu~(2+), Co~(2+), Ni~(2+) salts. The results revealed higher selectivity and efficiency towards Hg~(2+) over other metal cations; pentameric ligand 1 with six oxygen donor atoms provided the highest extractability of 83.3%, while dimeric ligand 3 extracted almost exclusively Hg~(2+). The stoichiometry of the extracted complex between ligand 1 and Hg~(2+), and the extraction constant (logK_(ex)) were determined in solvent extraction.