Ni(II) and Cu(II) complexes with ONNO asymmetric tetradentate Schiff base ligand: synthesis, spectroscopic characterization, theoretical calculations, DNA interaction and antimicrobial studies

Abstract

A novel Schiff base, namely Z‐3‐((2‐((E)‐(2‐hydroxynaphthyl)methylene)amino)‐5‐nitrophenylimino)‐1,3‐dihydroindin‐2‐one, was synthesized from the condensation of 2‐hydroxy‐1‐naphthaldehyde and isatin with 4‐nitro‐o‐phenylenediamine. It was structurally characterized on the basis of 1H NMR, 13C NMR and infrared spectra and elemental analyses. In addition, Ni(II) and Cu(II) complexes of the Schiff base ligand were prepared. The nature of bonding and the stereochemistry of the investigated complexes were elucidated using several techniques, including elemental analysis (C, H, N), Fourier transform infrared and electronic spectroscopies and molar conductivity. The thermal behaviours of the complexes were studied and kinetic–thermodynamic parameters were determined using the Coats–Redfern method. Density functional theory calculations at the B3LYP/6‐311G++ (d, p) level of theory were carried out to explain the equilibrium geometry of the ligand. The optimized geometry parameters of the complexes were evaluated using LANL2DZ basis set. The total energy of highest occupied and lowest unoccupied molecular orbitals, Mullikan atomic charges, dipole moment and orientation are discussed. Moreover, the interaction of the metal complexes with calf thymus DNA (CT‐DNA) was explored using electronic spectra, viscosity measurements and gel electrophoresis. The experimental evidence indicated that the two complexes could strongly bind to CT‐DNA via an intercalation mechanism. The intrinsic binding constants of the investigated Ni(II) and Cu(II) complexes with CT‐DNA were 1.02 × 106 and 2.15 × 106 M−1, respectively, which are higher than that of the standard ethidium bromide. Furthermore, the bio‐efficacy of the ligand and its complexes was examined in vitro against the growth of bacteria and fungi to evaluate the antimicrobial potential. Based on the obtained results, the prepared complexes have promise for use as drugs. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of the formation of silver nano‐binuclear complex on the refinement of cytotoxic and antibacterial potency of coumarin Schiff base: Spectroscopy, thermal, X‐ray diffraction analyses and density functional theory calculations

“…Monolayer cells were incubated with the compounds for 48 h at 37°C in an atmosphere of 5% CO 2 . After 48 h, cells were fixed, rinsed and stained with sulforhodamine B stain . Excess stain was washed with acetic acid and administered with Tris–EDTA buffer.…”

The crystal structure (E)-4-methyl-N′-(2-nitrobenzylidene)benzenesulfonohydrazide, C14H13N3O4S

“…These compounds may show excellent properties, such as antitumor and antibacterial activity [5,6], catalytic property [7,8], as fluorescent sensor [9] and so on. As part of our interest in synthesis, structure and property of Schiff base compounds, in this paper, a new Schiff base compound is reported.…”

Oxotitanium(IV) complexes of some bis‐unsymmetric Schiff bases: Synthesis, structural elucidation and biomedical applications

“…[2] Nowadays, the research on Schiff bases is increasing due to their ease of synthesis, structural variety, varied coordinating ability, thermal stability and catalytic activities. [5][6][7][8][9][10][11] An unsymmetric tridentate Schiff base ligand, 2-(2-nitrophenylthio)-N-((pyridine-2-yl) methylene)benzenamine, and its Mn(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized using various physicochemical and spectroscopic techniques and crystal X-ray diffraction. [5][6][7][8][9][10][11] An unsymmetric tridentate Schiff base ligand, 2-(2-nitrophenylthio)-N-((pyridine-2-yl) methylene)benzenamine, and its Mn(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized using various physicochemical and spectroscopic techniques and crystal X-ray diffraction.…”

“…[12] Fasina et al studied the synthesis, characterization and biological activity of unsymmetric N 2 O 2 Schiff bases obtained from the condensation of o-phenylenediamine with various salicylaldehydes. [9] Previously, titanium(IV) complexes of unsymmetric Schiff bases derived from ethylenediamine and o-hydroxyaldehyde/ketone have been synthesized and their antimicrobial properties have been evaluated. [9] Previously, titanium(IV) complexes of unsymmetric Schiff bases derived from ethylenediamine and o-hydroxyaldehyde/ketone have been synthesized and their antimicrobial properties have been evaluated.…”