Synthesis, Characterization and Thermodynamic Study of a Novel N-Functionalized Macrocycle And Its Metal Complexes

Abstract

A new N-carboxymethyl derivative of the tetraazamacrocyclic ligand LH_{4 ⁽}5,7,12,14-tetramethyl-1,4,8,11-tetraazamacrocyclo-tetradecane-N,N´,N"N''' -tetraacetic acid) and its complexes with Cu²⁺, Co²⁺, Ni²⁺, UO²⁺ and Th⁴⁺ have been synthesized and characterized by elemental analyses, UV, IR, ¹H NMR spectra and X -ray powder diffraction. The stability constants of mononuclear complexes of LH₄ with the ions above were determined at 35 ± 0.1, 45 ± 0.1 and 55 ± 0.1ºC in 0.5 mol L^–1 KNO₃ solution by means of potentiometric and computer fitting. The ΔH and ΔS of the coordination reactions in the solution were given.