Mixed ligand complexes of nickel(II) and cerium(III) ions with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1, 3-dimethyl-2,6-pyrimidine-dione and some nitrogen/oxygen donor ligands

Abstract

Mononuclear mixed ligand complexes of Ni(II) and Ce(III) with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1,3-dimethyl-2,6-pyrimidine-dione, 2-aminopyridine and 8-hydroxyquinoline have been prepared. The elemental analysis, molar conductance, spectral (IR, mass and solid reflectance), magnetic moment measurements and thermal study were utilized to investigate the coordination behavior. All metal complexes have metal-to-ligand ratios of 1:1:1 and the modes of bonding are consistent with N- and O-donation suggesting monomeric octahedral and square planar structures. The thermal behavior of these complexes was investigated and the thermal decomposition pathways postulated. The activation thermodynamic parameters, E*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of the complexes were calculated using the Coats-Redfern equation. Antibacterial and antifungal properties of the metal complexes have also been examined against Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 19615), Pseudomonas fluorescens (S 97), Pseudomonas phaseolicola (GSPB 2828), Fusarium oxysporum and Aspergillus fumigatus. The highest antimicrobial activity was observed for the Ce(III) complex, [CeL(8-Oqu)(NO₃)₂]·1½H₂O.

Keywords:

• 2-Aminopyridine
• 8-Hydroxyquinoline
• Mixed ligand complexes
• Spectroscopic characterization
• Thermal investigation and biological study