Synthesis, thermoanalytical and spectroscopic studies of trivalent lanthanides (Eu-Ho) complexes with the valsartan ligand

Abstract

Trivalent lanthanides (Eu-Ho) complexes with Valsartan ligand were characterized by analytical, thermoanalytical and spectroscopic techniques. The comparison of the thermal decomposition of the compounds were made by plotting a 2D contour map as a facilitator for the data visualization. The thermal behavior was discussed correlating three properties of the compounds: basicity and HOMO-LUMO orbitals of the lanthanides, and the strength of each bond in the molecule. The gaseous products released during the thermal decomposition were: NH3/N2H4, CO2, CO, N2O and an aliphatic compound in air atmosphere; NH3/N2H4, CO2, CO, an unknown compound (two bands between 1200−1100 cm−1), and an unsaturated ketone or a mixture of unsaturated hydrocarbon and a ketone in nitrogen atmosphere. The compounds presented an amorphous halo, except holmium; the ligand binds through the tetrazole ring and the carboxylate group binds the lanthanide in monodentate mode; finally, the degree of covalence of the Eu, Dy, and Ho complexes were determined.