Abstract:
Heterocyclic compounds are compounds that have a broad spectrum of biological activities.
1,10-phenanthroline derivatives have attracted considerable interest from both synthetic and
medicinal chemists. The aim of this study was to synthesize, characterize and evaluate
antibacterial activity of 1H-imidazo [5, 6-f][1, 10] phenanthroline-2(3H)-thione and its Ni (II)
and Cu (II) complexes. 1H-imidazo [5, 6-f][1, 10] phenanthroline-2(3H)-thione was synthesized
by direct reaction of 1, 10- phenanthroline-5.6-dione (PD) and thiourea (TU). The complexes of
Ni (II) and Cu (II) with this ligand were prepared by direct reactions of the chloride salts of the
metals and ligand (1:2) mole ratios in ethanol. The structures of synthesized ligand and metal
complexes were characterized and confirmed by elemental analyses (C, H, N and S), FT-IR, 1HNMR, 13C-NMR, Atomic absorption spectroscopy, UV-Vis spectra and molar conductivity
measurement. The data from the elemental analysis suggest a good agreement between the
calculated and the experimental values for the elements and the IR studies revealed that ligand
acted as bidentate through nitrogen atoms in synthesized complexes. The metal complexes were
isolated in good yield and are thermally stable. The molar conductivity measurements of the
complexes indicates that their electrolytic nature and geometry structure. On the basis of spectral
studies an octahedral geometry for Ni (II) complex and distorted octahedral geometry for Cu (II)
complex. A comparative antibacterial study test was performed using the disk diffusion method
against on two gram positive bacterial (Staphylococcus aureus (ATCC 25923), Bacillus subtillus
(ATCC 6633) and two gram negative bacteria (Escherichia coli (ATCC 35218) and
pseudomonas aeruginosa (ATCC 27853). Ni (II) complex shows higher bioactivity than
Gentamicin against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 27853)
while Cu (II) complex is more bioactive than Ni (II) complex against Bacillus subtilis. The Cu
(II) and Ni (II) complexes exhibit higher antibacterial activities than the free ligand.
