Synthesis, Characterization and Antimalarial Studies of Cd(II), Cu(I) and Ni(II) Complexes of 5-(4-Chlorophenyl)-6-Ethyl-2,4-Pyrimidinediamine and 4-Amino-N-(5,6-Dimethoxy-4-Pyrimidinyl) Benzenesulfonamide Mixed Ligand

Cd(II), Cu(I) and Ni(II) complexes of 5-(4-chlorophenyl)-6-ethyl-2,4-pyrimidinediamine (pyrimethamine) and 4-Amino-N-(5,6-dimethoxy-4-pyrimidinyl) benzenesulfonamide (sulfadoxine) mixed ligand have been synthesized. The melting point, solubility, yield and colour of the complexes were determined. The mixed ligand and complexes are stable, non hygroscopic, exhibited high melting points and are soluble in polar solvents. The complexes were characterized based on ultraviolet-visible and infrared spectroscopy. The electronic spectra of the ligands and complexes showed intraligand charge transfer (ILCT), ligand to metal charge transfer (LMCT) and d→d transitions. Infrared spectrum of cadmium complex suggested coordination through NH₂ groups of pyrimethamine and sulfadoxine. The infrared spectra of Cu(I) and Zn(II) suggested complexation through one NH₂ group of pyrimethamine (monodentate) and S=O group of sulfadoxine (bidentate). A trigonal geometry was suggested for the metal complexes. Antimalarial investigations showed that sulfadoxine/pyrimethamine-metal complexes are more effective than sulfadoxine/pyrimethamine alone against strains of Plasmodium berghei.