The tridentate N 4 -type Schiff base was synthesized from the condensation reaction of 2-hydrazinopyridine and pyridine-2-carbaldehyde. Neodymium and Samarium complexes were isolated when the corresponding nitrate salt was added to the solution of the ligand. The isolated compounds were characterized by elemental analyses, IR study, room temperature magnetic measurements and single X-ray crystal diffraction of the two crystals. Both complexes crystallize in the monoclinic system with space group P21/c.
KEYWORDSLanthanide complexes, hydrazino, antioxidant activity, X-ray structure.
In the title compound, [Tb(H2L)2(H2O)3].3Cl.4(H2O).(C2H5OH), the Tb3+ is nine-coordinated in a distorted monocapped square antiprismgeometry by four nitrogen atoms, two oxygen atoms from the ligand molecules of the tridentate N,N'-1,5-bis(pyridylmethylidene) carbonohydrazone) (H2L) and three oxygen atoms of coordinating water molecules. The structure of the complex was elucidated by X-ray diffraction analysis. Suitable crystals were grown by slow evaporation of ethanol solution. The compound crystallizes in the triclinic crystal system with a space group of Pī. The asymmetric unit of the compound contains two neutral ligand molecules, oneterbium ion, three coordinated water molecules, five and half uncoordinated water molecules and one uncoordinated ethanol molecule. In the crystal, the complex cations are linked by hydrogen bonds into layers. These layers, chloride anions and non-coordinating water molecules are connected by O—H···O, O—H···N, O—H···Cl, N—H···O, N—H···Cl and C—H···Cl hydrogen bonds into a three-dimensional structure.
The tridentate N4-type Schiff base was synthesized in situ from the condensation reaction of 2-hydrazinopyridine and pyridine-2 carbaldehyde. Novel lanthanide(III) (Ln= Ce, Pr, Gd and Er) complexes were isolated when lanthanide(III) nitrate salt were added to the solution of the ligand. The complexes were characterized by IR spectra, room temperature magnetic measurement, elemental analyses and the structure of the Ce(III) complex was determined by X-ray single crystal diffraction . The complex crystallizes in the monoclinic system with space group P21/c. The geometry around the metal center shows distorted tricapped trigonal prism. It is noteworthy that the tridentate Schiff base acts as tridentate ligand leading ninecoordinate complex. The antioxidant studies show that the values of IC50 of the ligand HL and complexes 1 -3 at 40 mg/L on the DPPH• radical scavenging effects are respectively 16.32 ± 0.03, 3.72 ± 0.02, 12.05 ±0.04 and 8.95 ± 0.01 M, respectively. The values of IC50 present the order 1 < 3 < 2 < HL.[1] R. E. Mewis and S.
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