New macrocycles based on pyrazole-tetrazole subunit: synthesis, characterization and their complexing properties toward heavy metal cations

Abstract

The synthesis of tree new macrocycles with two pyrazole–tetrazole subunits and a lateral arm is described. These macrocycles were characterized by NMR, FT-IR and UV–Vis spectroscopies as well as elemental analysis and mass spectrometry. The complexing properties of these compounds toward some heavy metal ions Pb²⁺, Co²⁺, Cd²⁺, Zn²⁺ and Cu²⁺ were investigated by liquid–liquid extraction. The obtained results show, that all macrocycles possess good ability to extract these heavy metal cations, except, the macrocycle M_III with an aromatic side chain which showed a weak potency. At the competitive conditions, all macrocycles presented some selectivity towards the extraction of Cd²⁺. In addition, the ability of these macrocycles to extract the cadium cation is affected by the pH of the solution.