Synthesis and characterization of some new Cd(II) and Zn(II) macrocyclic Schiff base complexes derived from cyclocondensation of three new linear aromatic (N4) amines and 2,6-diacetylpyridine. Crystal structure and biological activity studies

Six new Cd(II) and Zn(II) macrocyclic Schiff base complexes from cyclocondensation of 2,6-diacetylpyridine and three different liner aromatic amines have been investigated. The resulting ligands, L-1 and L-2 are 17- and L-3 18-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods such as IR, elemental analysis, EI-Mass and conductivity measurements and in the case of cadmium complex by H-1 and C-13 NMR spectroscopy. The crystal structure of [CdL1(CH3OH)](ClO4)(2) has been determined. In this complex, the Cd(II) ion is coordinated to five nitrogen donor atoms of the ligand and one oxygen atom from methanol in a N5O environment. The geometry around the cadmium can be better described as in a slightly distorted pentagonal-pyramidal. The synthesized compounds have antibacterial activity against the three gram-positive bacteria: S. aureus, B. cereus and C. xerosis, and also against the three gram-negative bacteria: E. coli, K. pneumoniae and P. vulgaris. The results show that the antibacterial activity of cadmium complexes is greater than that of zinc complexes.