Antibacterial Co(II), Ni(II), Cu(II) and Zn(II) complexes with biacetyl-derived Schiff bases

Abstract

The condensation reactions of biacetyl with ortho-hydroxyaniline and 2-aminobenzoic acid to form bidendate NO donor Schiff bases were studied. The prepared Schiff base ligands were further utilized for the formation of metal chelates having the general formula [ML 2 (H 2 O) 2 ] where M = Co(II), Ni(II), Cu(II) and Zn(II) and L = HL 1 and HL 2 . These new compounds were characterized by conductance measurements, magnetic susceptibility measurements, elemental analysis, and IR, 1 H-NMR, 13 C-NMR and electronic spectroscopy. Both Schiff base ligands were found to have a mono-anionic bidentate nature and octahedral geometry was assigned to all metal complexes. All the complexes contained coordinated water which was lost at 141-160 °C. These compounds were also screened for their in vitro antibacterial activity against four bacterial species, namely: Escherichia coli, Staphylococcus aureus, Salmonella typhi and Bacillus subtilis. The metal complexes were found to have greater antibacterial activity than the uncomplexed Schiff base ligands.

Spectral, thermal and magnetic properties of Cu(II) and Ni(II) complexes with Schiff base ligands

“…In addition to this characteristic (C=N) absorption, these ligands also exhibit broad medium bands with a maximum around 3440 cm -1 , which can be assigned to phenolic (O-H) group vibrations. 8,9,[23][24][25][26][27][28][29][30] A strong band observed at 1216-1276 cm −1 in the free Schiff bases is assigned to the phenolic C-O stretching vibration. In the IR spectra of the Schiff base complexes (Table II), the band due to ν(C=N) showed a negative shift and appeared at 1632-1604 cm −1 , indicating coordination of the azomethine nitrogen to copper and nickel metals, respectively.…”

Cytotoxic Anthranilic Acid Derivatives from Deep Sea Sediment-Derived Fungus Penicillium paneum SD-44

“…Chemical investigation of this fungus by static culture in solid rice medium led to the isolation of one novel triazole and two new quinazolinone alkaloids, penipanoids A–C [11]. During our ongoing exploration of new bioactive metabolites of this fungal strain by changing fermentation conditions, we had a chance to access a large-scale bioreactor, and, as a result, six anthranilic acid derivatives including five new ones ( 1 – 5 ) and one previously synthesized analogue ( 6 ) [12] (Figure 1) were isolated from the culture broth of the dynamic fermentation in a 500-L fermentator. All the isolated new compounds possess an amidine moiety, which is rare among naturally occurring compounds [13].…”

Synthesis, characterization and antimicrobial studies on Schiff base derived from 2-aminopyridine and 2-methoxybenzaldehyde and its cobalt (ii) and nickel (ii) complexes

“…On a similar note, the peak at 1242 cm -1 which shifted to 1232 and 1294cm -1 in Co (II) and Ni (II) complexes respectively were assigned to C-O bond of the methoxy group (Abdel-Latif et al,2006). Table 4 shows magnetic susceptibility measurement of the complexes, The effective magnetic moment of the complexes, as determined from the magnetic susceptibility, were 4.51BM and 2.95BM for the cobalt (II) and nickel (II) complexes respectively, which suggests high spin complexes with octahedral geometry (Imran et al, 2010). 65.720 x 10 -7 3.642 x 10 -3 2.95 L = Ligand, C 13 H 12 N 2 O Table 5 shows the molar conductance as determined from the electrical conductance in 0.003M DMSO solution of the complexes which suggest a non electrolytic nature.…”