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

Abstract

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-amino- 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 ?, b = 11.706081 ? and c = 54.46780 ?) 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 bacteria 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), complex 8), indicated that the metal complexes exhibited a higher or lower antimicrobial activity than 2-chlorobenzylidene-2-amino-4-chlorophenol as the free ligand (B).

Microwave Synthesis, Reactivity, Spectral and Thermal Analysis of Some Binary/Mixed Ligand Oxovanadium(IV) Complexes

“…Characteristic absorption bands observed at 750 cm -1 in this complex are due to coordination of metavanadate ion through oxygen. This supported by some new bands at 550 cm -1 and 510 cm -1 in the complex spectrum have tentatively been assigned to υ(V-O) and υ(V-N) [14][15][16][17][18][19][20] .…”

“…The new band of medium intensity at 526 cm -1 in the spectrum of complex has been assigned to υ(V-O). A broad band around 3250-3300 cm -1 is due to lattice water [14][15][16][17][18][19][20] .…”

“…Some other bands of appreciable intensity between 1000-500 cm -1 in complex spectrum are assignable to oxovanadium(IV) and free metavanadate ions i.e. υ(V=O), υ(VO 3 ) and υ(V-O) [14][15][16][17][18][19][20] . The ligand dnph (VI) exhibits a medium intensity band at 1017 cm -1 due to υ(N-N).…”

Microwave synthesis and spectral, thermal and antimicrobial activities of some novel transition metal complexes with tridentate Schiff base ligands

“…There was no appreciable change in the ν(C=N) at 1496 cm -1 in ligand on complex formation, which indicates that the pyridine ring nitrogen does not participate in the coordination. [26][27][28][29][30] IR spectrum of the HNAC ligand showed the most characteristic bands at 1613 cm -1 ν(C=N, azomethine), 1675 cm -1 ν(C=O) and 1236 cm -1 ν(C-O). The ligand spectrum showed bands at 3230 and 1336 cm -1 due to the stretching and deformation of the phenolic OH.…”

Synthesis, Structural Characterization and Anti-bacterial Activity of some Novel Schiff base Ligands and their Vanadium (IV) Metal Complexes

“…Table [12][13][14][15] . The singlet appeared at 12.04 ppm due to phenolic hydroxyl proton is absent in the NMR spectrum of VO complex indicating the deprotonation of hydroxyl group and the involvement of that oxygen in coordination.…”