Template-engineered metal macrocyclic complexes: Synthesis and biological activity

Three new azamacrocylic complexes of divalent transition-metal ions were synthesized by taking Co(II), Ni(II), and Cu(II) metal ions as templates. The macrocyclic ligand (1²Z,5²Z,5⁴E)-1¹,1²,1³,1⁴,1⁵,1⁶,5¹,5²,5³,5⁴,5⁵,5⁶-dodecahydro-2,4,6,8-tetraaza-1 (2,4),5(4,2)-pyrimidine-3,7(1,2)-dibenzenacyclooctaphane-1⁶,5⁶-dione was derived from o-phenylenediamine (OPD) and 2-thiobarbituric acid (TBA). All the complexes were fully characterized through spectroscopic techniques and elemental analyses. The structures of the macrocyclic complexes were determined by IR, UV–vis, ESI-MS, TGA, molar conductance, magnetic moment, and electron spin resonance data. On the basis of the above studies, the complexes may be formulated as MLX₂], in which L is a macrocyclic ligand and X = CH₃COO⁻. All the macrocyclic complexes were biologically screened to evaluate their antimicrobial efficacy. DNA binding study of two representative complexes was performed by UV–vis titrations.