Synthesis of a New Aza-crown Ether Containing Pendant Carboxylate Groups, Its Th4+ and UO22+ Complexes and Thermodynamic Properties in Aqueous Solution

Abstract

A novel tetraazamacrocycle containing pendant carboxylate group L₁H₄ (5,12-diphenyl-7,14-dimethyl-1,4,8,11-tetraazamacrocyclotetradecane-N,N’,N”,N”’-tetraacetic acid) and its complexes with Th⁴⁺ and UO₂²⁺ have been synthesized and characterized by elemental analyses, IR, ¹H NMR spectra, conductivity measurement, TG-DTA analyses and X-ray powder diffraction. The stability constants of mononuclear complexes of L₁H₄ with the Th⁴⁺ and UO₂²⁺ were determined at 35 ± 0.1 , 45 ± 0.1 and 55 ± 0.1 ºC in 0.5 mol.L^-1 KNO₃ solution by means of potentiometric and computer fitting. The aH and aS of the coordination reactions in the aqueous solution were given.