Synthesis, characterization, crystal structure and antibacterial studies of some new heptadentate manganese(II), cadmium(II) and zinc(II) macrocyclic Schiff base complexes with two 2-pyridylmethyl pendant arms

Two new branched hexadentate amines, 4,8-bis(2-pyridylmethyl)-4,8-diazaundecane-1,11-diamine (1) and 4,9-bis(2-pyridylmethyl)-4,9-diazadodecane-1,12-diamine (2), have been synthesized. Condensation with 2,6-diacetylpyridine in methanol in the presence of manganese(II), zinc(II) and cadmium(II) ions leads to produce some new Schiff base macrocyclic complexes with two 2-pyridylmethyl pendant arms. The X-ray crystal structure of the resulting manganese(II) complex, [MnL1](ClO4)(2) center dot H2O (3), is reported here. It has been shown that the manganese atom is bonded to five nitrogens of a macrocyclic ring and two nitrogens of the pendant arms. The arrangement is slightly distorted to pentagonal bipyramidal whereas the nitrogens of 2-pyridylmethyl groups occupy apical positions. The synthesized complexes were screened for their antibacterial activities against four bacterial strains and the complexes showed antibacterial effects.