Complexation of 4-amino-1,3 dimethyl-2,6 pyrimidine-dione derivatives with cobalt(II) and nickel(II) ions: synthesis, spectral, thermal and antimicrobial studies

Abstract

Four heterocyclic Schiff-base ligands derived from condensation of 4-amino-1,3 dimethyl-2,6 pyrimidine-dione with 2-hydroxybenzaldehyde, 2-methoxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde and 4-(dimethylamino) benzaldehyde, (HL¹, L², HL³and L⁴), respectively, and their Co(II) and Ni(II) complexes have been prepared and characterized via elemental analysis, molar conductance, magnetic moment, thermal and XRPD analysis as well as spectral data (IR, ¹H-NMR, mass and solid reflectance). IR data reveal that the ligands are bidentate neutral ligands except HL¹, which is monobasic tridentate with coordination sites azomethine (N), carbonyl (O) and phenolic (O). Conductance data suggest that all complexes are non-electrolytes, except cobalt(II) complexes of L²and HL³are 1 : 1 electrolytes. The mass spectra confirm the proposed structure of the ligands and their complexes. The solid reflectance spectral data and magnetic moment measurements suggest octahedral, tetrahedral and square planar geometrical structures for the metal complexes. The spectral data were utilized to compute the important ligand field parameters B, β and Dq; LFSE also was calculated. The thermal behavior is also studied. Antibacterial and antifungal properties of the ligands and their complexes show broad-spectrum activities and the metal complexes show higher activity than the free ligands.

Keywords:

• Heterocyclic Schiff-base ligands
• Metal complexes
• Electronic spectra
• Biological study