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

Abstract

Two novel Schiff base ligands (La and Lb) were prepared from the condensation of quinoline 2‐aldehyde with 2‐aminopyridine (ligand La) and from the condensation of oxamide with furfural (ligand Lb). Mixed ligand complexes of the type M+2La/b Lc were prepared, where (La and Lb) the primary ligands and Lc was 2,6‐pyridinedicarboxylic acid as secondary ligand. Metal ions used were Fe(II), Co(II), Ni(II) and Zn(II) for mixed ligands La Lc and Fe(II), Co(II), Ni(II), Cu(II), Hg(II) and Zn(II) for LbLc mixed ligands. La and Lb Schiff base ligands were both characterized using elemental analyses, molar conductance, IR, 1H and 13C NMR. Mass spectra for Lb, [Zn(La)LcCl]Cl and [Cu(Lb)LcCl]Cl were also studied. ESR spectrum of the [Cu(Lb) LcCl]Cl complex was also recorded The metal complexes were synthesized and characterized using elemental analyses, spectroscopic (IR, 1H NMR, UV‐visible, diffused reflectance), molar conductance, magnetic moment and thermal studies. The IR and 1H 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 La and Lb ligands behaved as neutral bidentate ligands with N2 donation sites (quinoline N and azomethine N for La and two azomethine N for Lb). 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 La, Lb 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.

Step-by-Step and Competitive Assembly of Two Dy(III) Single-Molecule Magnets with Their Performance Tuned by Schiff Base Ligands

“…Given the current major interest in the synthesis of coordination clusters with programmed structures and functions, − the following factors must be considered in the design and synthesis of clusters to obtain different structures and specific physicochemical properties: species, symmetry, topology and number of metal ions and type, shape and number of ligands, and intra- and intermolecular interactions . A common practice in the design of coordination clusters is to use an organic ligand with the appropriate geometry, dimensions, and donor atoms in the required places to generate the required molecule or network by self-assembly of the metal centers. − , Previously, the design and synthesis of clusters relied on a single “key” organic ligand and formed by anionic bridging of OCH 3 – , OH – , Cl – , or N 3 – . , In recent years, an increasing number of clusters of mixed organic ligands have been developed, and the introduction of various ligands has greatly improved and expanded the properties of clusters − (e.g., magnetic, − photoluminescence, catalysis, − and biological activity). However, the key to the design and synthesis of mixed ligand clusters is the choice of organic ligands. − , Usually, only mixed organic ligands with a similar coordination ability and shape can realize the design and synthesis of mixed ligand clusters, greatly limiting the ...…”

“…[1][2][3][4][5][6][7][8]14 Previously, the design and synthesis of clusters relied on a single "key" organic ligand and formed by anionic bridging of OCH 3 − , OH − , Cl − , or N 3 − . 1,15 In recent years, an increasing number of clusters of mixed organic ligands have been developed, and the introduction of various ligands has greatly improved and expanded the properties of clusters 16−29 (e.g., magnetic, 16−25 photoluminescence, 26 catalysis, 18−27 and biological activity 29 ). However, the key to the design and synthesis of mixed ligand clusters is the choice of organic ligands.…”

Synthesis, Spectroscopic Properties, Anti-Breast Cancer and Anti-Microbial Studies of Some Metal Complexes for New Schiff Base Ligand Derived From Anthranilic Acid.

“…The diffused re ectance spectral data of Ni(II) complex showed d-d bands in the region 16,694,18.115 and 25,740 cm -1 , respectively [30], assigned to 3 A 2g (F)→ 3 T 2g (F), 3 A 2g (F)→ 3 T 1g (F) and 3 A 2g (F)→ 3 T 2g (F) transitions, which were characteristic of Ni(II) in octahedral geometry [31]. The Ni(II) complex exhibited magnetic moment value of 2.44 BM attributed to two unpaired electrons per Ni(II) ion suggesting that this complex has an octahedral geometry [32].…”

Synthesis, Spectral Characterization, Docking Analysis, DNA Binding/Cleavage, Antimicrobial and Cytotoxic Activity of New Dimeric Antipyrine-Schiff Base Metal Complexes

“…8, which evidently explicates that Schiff base ligand and its metal complexes with DNA through an intercalation mode concerning outside edge stacking contact with the oxygen atom of the phosphate backbone, it is clear that the ligand and dimeric metal(II) complexes were to be positioned suitably into the intercalation mode of targeted DNA. In addition, resultant structures are stabilized by the vander Waal's interaction and hydrophobic contacts with DNA functional group that delineate the stability of interaction [58]. The docking scores of molecular docked ligand and the dimeric metal(II) complexes (Cu 2+ , Co 2+ , Ni 2+ , Zn 2+ ) are found to be (-253.4), (-289 .7), (-289.5), ( -289.3), (-289.2), respectively.…”