Acta Pharm. 54 (2004) 119-131

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Original research paper  
 

Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol

IRENA P. KOSTOVA,1* ILIA I. MANOLOV2 and  MARITZA K. RADULOVA3

irenakostova@yahoo.com


1Department of Chemistry, Faculty of Pharmacy, Medical University, Sofia 1000, Bulgaria
2Department of Industrial Pharmacy, Faculty of Pharmacy, Medical University, Sofia 1000, Bulgaria
3 Department of Technology, Faculty of Pharmacy, Medical University, Sofia 1000, Bulgaria
Received July 7, 2003      Accepted February 24, 2004

A complex of neodymium(III) with 4-hydroxy-3-[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3x6H2O, where R = C19H14NO6-. The reaction of neodymium(III) with 4-hydroxy-3-[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 0.06; log K2 = 3.46 0.07 and log K3 = 2.58 0.05, respectively.


Keywords: neodymium(III) complex, 4-hydroxy-3-[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one, stability