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Synthesis, spectroscopic, thermal analyses, biological activity and molecular docking studies on mixed ligand complexes derived from Schiff base ligands and 2,6‐pyridine dicarboxylic acid
Author(s) -
Abd ElHalim Hanan F.,
Mohamed Gehad G.
Publication year - 2018
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.4176
Subject(s) - chemistry , denticity , ligand (biochemistry) , schiff base , pyridine , carboxylate , metal ions in aqueous solution , metal , octahedral molecular geometry , protonation , proton nmr , stereochemistry , medicinal chemistry , crystallography , inorganic chemistry , crystal structure , ion , organic chemistry , biochemistry , receptor
Two novel Schiff base ligands (L a and L b ) were prepared from the condensation of quinoline 2‐aldehyde with 2‐aminopyridine (ligand L a ) and from the condensation of oxamide with furfural (ligand L b ). Mixed ligand complexes of the type M +2 L a/b L c were prepared, where (L a and L b ) the primary ligands and L c was 2,6‐pyridinedicarboxylic acid as secondary ligand. Metal ions used were Fe(II), Co(II), Ni(II) and Zn(II) for mixed ligands L a L c and Fe(II), Co(II), Ni(II), Cu(II), Hg(II) and Zn(II) for L b L c mixed ligands. L a and L b Schiff base ligands were both characterized using elemental analyses, molar conductance, IR, 1 H and 13 C NMR. Mass spectra for L b , [Zn(L a )L c Cl]Cl and [Cu(L b )L c Cl]Cl were also studied. ESR spectrum of the [Cu(L b ) L c Cl]Cl complex was also recorded The metal complexes were synthesized and characterized using elemental analyses, spectroscopic (IR, 1 H NMR, UV‐visible, diffused reflectance), molar conductance, magnetic moment and thermal studies. The IR and 1 H NMR spectral data revealed that 2,6‐pyridinedicarboxalic acid ligand coordinated to the metal ions via pyridyl N and carboxylate O without proton displacement. In addition, the IR data showed that L a and L b ligands behaved as neutral bidentate ligands with N 2 donation sites (quinoline N and azomethine N for L a and two azomethine N for L b ). Based on spectroscopic studies, an octahedral geometry was proposed for the complexes. The thermal stability and degradation of the metal complexes were investigated by thermogravimetric analysis. The binding modes and affinities of L a , L b and Zn(II) complexes towards receptors of crystal structure of E. coli (PDB ID: 3 t88) and mutant oxidoreductase of breast cancer (PDB ID: 3 hb5) receptors were also studied. The antimicrobial activity against two species of Gram positive, Gram negative bacteria and fungi were tested for the Schiff base ligands, 2,6‐pyridinedicarboxylic acid and the mixed ligand complexes and revealed that the synthesized mixed ligand complexes exhibited higher antimicrobial activity than their free Schiff base ligands.