Stability of Neodymium(III) Complexes of 4-Hydroxycoumarins with Anticoagulant Activity

Complexes of neodymium(III) with 4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one, 4-hydroxy-3-[1-(4-chlorophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one and 4-hydroxy-3-[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one were synthesized by mixing of water solutions of neodymium(III) nitrate and the respective ligands, in amounts equal to metal: ligand molar ratio of 1: 3. The complexes were characterized and identified by elemental analysis, conductivity, IR and ¹H NMR spectral data. DTA and TGA have been applied to confirm the compositions of the compounds. The formation of the complexes was studied by IR-and ¹H-NMR-spectroscopy. The complexation reactions were studied in detail by spectrophotometric method. The stepwise formation of the complexes has been established in the pH region studied. The equilibrium constants for the complexes have been determined. The complexes of neodymium(III) with 4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one, 4-hydroxy-3-[1-(4-chlorophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one and 4-hydroxy-3-[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one were assayed for acute intraperitoneal and per oral toxicity and for influence on blood clotting time.