Structural and antimicrobial studies of coordination compounds of VO(II), Co(II), Ni(II) and Cu(II) with some Schiff bases involving 2-amino-4-chlorophenol

Complexes of tailor-made ligands with life essential metal ions may be an emerging area to answer the problem of multi-drug resistance (MDR). The coordination complexes of VO(II), Co(II), Ni(II) and Cu(II) with the Schiff bases derived from 2-hydroxyacetophenone/2-chlorobenzaldehyde with 2-ami- no-4-chlorophenol were synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, ESR, FAB mass, thermal and magnetic susceptibility measurements. The FAB mass and thermal data show degradation of the complexes. The ligand A (2-hydroxyacetophenone-2amino- -4-chlorophenol) behaved as tridentate and ligand B (2-chlorobenzylidene-2- -amino-4-chlorophenol) as bidentate, coordinating through O and N donors. The complexes (VO(A)(H2O))⋅xH2O, (M(A)(H2O)n)⋅xH2O for Co and Ni, (Cu(A)(H2O)) and (VO(B)2)⋅xH2O, (M(B)2(H2O)n) for Co and Cu and (Ni(B)2) exhibited coordination numbers 4, 5 or 6. X-ray powder diffraction data (a = = 11.00417 Å, b = 11.706081 Å and c = 54.46780 Å) showed that (Cu(CACP)2(H2O)2), complex 8, crystallized in the orthorhombic system. The in vitro biological screening effects of the investigated compounds were tested against the bac- teria Escherichia coli, Staphylococcus aureus and Streptococcus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by the serial dilution method. A comparative study of the MIC values of the Schiff base and their (M(B)2(H2O)2) complexes (Co(II), complex 6 and Cu(II), com- plex 8), indicated that the metal complexes exhibited a higher or lower antimic- robial activity than 2-chlorobenzylidene-2-amino-4-chlorophenol as the free li- gand (B).