Cobalt and Zinc Complexes
131
well with corresponding bond lengths in other complexes
with tetrahedrally coordinated zinc atoms.[21,22]
The crystal packing of the complex is shown in Figure 4.
The dinuclear zinc complex cations are linked by iodide
anions through intermolecular NÀÀH¢¢¢I hydrogen bonds, to
form 1D chains running along the a-axis.
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Antibacterial Activities
The Schiff base ligands HLa and HLb have also the same
activities against E. coli, and no activity again from B. subtilis
and S. aureus. The cobalt and zinc complexes have from
weak to medium activities against the three strains. In gen-
eral, the complexes have stronger antibacterial activities than
the free Schiff base ligands. It is obvious that complex (1) has
stronger activities against the bacteria than complex (2).
However, when compared with Penicillin and Kanamycin,
the activities of the Schiff bases and the complexes are far
weaker. Detailed comparison among the compounds can
simply conclude that the substitute groups and their positions
of the Schiff base ligands are not crucial for the antibacterial
activity. Yet, the combination of metal atoms can enhance
the antibacterial activities.
Conclusions
New cobalt and zinc complexes were synthesized and charac-
terized with the help of microanalytical, IR spectroscopic,
and single-crystal X-ray crystallographic measurements. The
crystal structures of the complexes reveal that the Co atom is
in a distorted octahedral coordination sphere and the Zn
atoms are in tetrahedral coordination spheres. The complexes
have from weak to medium antibacterial activities on the
strains B. subtilis, E. coli, and S. aureus.
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14. Khalaji, A. D.; Weil, M.; Grivani, G.; Akerdi, S. J. Synthesis, char-
acterization, and crystal structure of two zinc(II) halide complexes
with the symmetrical bidentate Schiff-base ligand (3,4-MeO-ba)2en.
Monatsh Chem. 2010, 141, 539–543.
Supplemental Material
CCDC 934999 (1) and 935000 (2) contain the supplementary
crystallographic data for the complex. These data can be
15. Sebastian, M.; Arun, V.; Robinson, P. P.; Leeju, P.; Varghese, D.;
Varsha, G.; Mohammed Yusuff, K. K. Synthesis, characterization,
and structure of a new cobalt(II) Schiff-base complex with quinoxa-
line-2-carboxyalidine-2-amino-5-methylphenol. J. Coord. Chem.
2010, 63, 307–314.
16. Qian, J.; Tian, J.-L.; Feng, L.; Gu, W.; Zhao, X.-J.; Yan,
S.-P. Syntheses, structures, and spectroscopic properties of
binuclear copper(II) complexes containing N,N-bis(2-pyridyl-
methyl)amine ligands. ased Schiff bases. J. Coord. Chem.
2009, 62, 3276–3283.
Funding
The authors are grateful to Hebei Key Laboratory of Bioi-
norganic Chemistry and College of Sciences of Agricultural
University of Hebei for financial support.
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