Synthesis, fluorescent studies, antioxidative and α-amylase inhibitory activity evaluation of some lanthanide(III) complexes

Abstract

A novel heterocyclic ligand, viz. 1,2-dihydro-1,5-dimethyl-4-[[1-2-
-oxo-2H-1-benzopyran-3-yl)ethylidene]amino]-2-phenyl-3H-pyrazol-3-one, was prepared by condensing 3-acetylcoumarin with 4-aminoantipyrine. This ligand is versatile in forming complexes with lanthanum(III), praseodymium(III), samarium(III), gadolin­ium(III) and dysprosium(III) ions. The ligand and the metal complexes were characterized through various physicochemical and spectral studies. The spec­tral studies revealed that the ligand is coordinated to the metal ion in a biden­tate fashion, through the azomethine nitrogen and the oxygen atom of the pyra­zolone ring. The powder XRD patterns of ligand and the dysprosium(III) com­plex were studied. The photoluminescent properties of ligand and metal com­plexes were evaluated and the relative quantum yields were determined. It was observed that in all cases the metal ions enhanced the luminescence intensity. The α-amylase inhibitory activity of the ligand and the metal complexes was evaluated using the method of Apostolidis. The metal complexes exhibited inc­reased activity compared to the ligand. The antioxidant property was also examined using the DPPH assay and the metal complexes were found to be more potent antioxidants than the ligand.