Synthesis, Spectral Characterization, DNA Binding Studies and Antimicrobial Activity of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) Complexes with 4-Aminoantipyrine Schiff Base of Ortho-Vanillin

Abstract

A series of transition metal complexes of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) have been synthesized involving the Schiff base, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-3-methoxy benzylideneamino)-pyrazol-5-one(L), obtained by condensation of 4-aminoantipyrine with 3-methoxy salicylaldehyde. Structural features were obtained from their FT-IR, UV-vis, NMR, ESI Mass, elemental analysis, magnetic moments, molar conductivity and thermal analysis studies. The Schiff base acts as a monovalent bidentate ligand, coordinating through the azomethine nitrogen and phenolic oxygen atom. Based on elemental and spectral studies six coordinated geometry is assigned to Co(II), Ni(II), Fe(III) and VO(IV) complexes and four coordinated geometry is assigned to Zn(II) complex. The interaction of metal complexes with Calf thymus DNA were carried out by UV-VIS titrations, fluorescence spectroscopy and viscosity measurements. The binding constants (K(b)) of the complexes were determined as 5 × 10(5) M(-1) for Co(II) complex, 1.33 × 10(4) M(-1) for Ni(II) complex, 3.33 × 10(5) M(-1) for Zn(II) complex, 1.25 × 10(5) M(-1) for Fe(III) complex and 8 × 10(5) M(-1) for VO(IV) complex. Quenching studies of the complexes indicate that these complexes strongly bind to DNA. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through groove. The ligand and it's metal complexes were screened for their antimicrobial activity against bacteria. The results showed the metal complexes to be biologically active, while the ligand to be inactive.

Novel Schiff base ligand and its metal complexes with some transition elements. Synthesis, spectroscopic, thermal analysis, antimicrobial and in vitro anticancer activity

“…The electronic spectra of the Schiff base ligand and its complexes were recorded in DMF solvent within the wavelength range 200–700 nm. In the UV–visible spectrum of the Schiff base ligand, two absorption bands are observed at 217 and 246 nm which may be assigned to π–π* transitions of the aromatic rings . Also, the absorption band at 333 nm may be assigned to n–π* transition of the azomethine or carboxylate groups.…”

Synthesis and Conformational Analysis of Aminopyrazolonyl Amino Acid (APA)/Peptides

“…This -keto ester (2) was treated with phenylhydrazine under mild acidic conditions for preparation of aminopyrazolone derivative (3). All compounds (3)(4)(5)(6) were characterized by NMR ( 1 H/ 13 C) and ESI-HRMS (See Electronic Supporting Information, ESI). To introduce carboxylate group at pyrazolone ring, compound (3) was treated with methyl bromoacetate under basic conditions.…”

“…General Procedure of Alkylation: O-alkylated (4), N-alkylated (5) and C-alkylated (6) products. To a stirred solution of 3 (1.0 g, 3.46 mmol) in AcCN (35 mL) was added anhydrous K 2 CO 3 (1.43 g, 10.3 mmol) and stirred for 30 min.…”

“…[5] For an example, the amino substituted pyrazolone molecule, ampyrone, has been modified as Schiff base derivatives and employed for metal complexation with metal ions (Co 2+ /Ni 2+ /Fe 3+ ) which are considered as antimicrobial agents. [6] Further, ampyrone is explored as biochemical reagent for determination of phenol concentration including inside the cell. [7] Moreover, pyrazole and pyrazolone derivatives have abilities to form hydrogen bonding and have been explored in screening of their biological activities.…”

Characterization of Antimicrobial, Antioxidant, and Leishmanicidal Activities of Schiff Base Derivatives of 4-Aminoantipyrine

“…However, even regarding the chemotherapeutic applications, the reported roles are very divergent, sometimes with proposed roles that could seem contradictory. For example, antioxidant activity has been ascribed to Schiff bases, acting as cell-protective agents [12,13,14,15], but antimicrobial [16,17], antitumor [18,19], analgesic [12], anti-inflammatory [9], and antidiabetic activities [8,18] have also been reported. A detailed review covering the patented therapeutics applications of Schiff bases has been published by Khan and collaborators [18].…”