Syntheses, characterization, and biological activity of novel mono- and binuclear transition metal complexes with a hydrazone Schiff base derived from a coumarin derivative and oxalyldihydrazine

Abstract

A hydrazone Schiff base ligand was synthesized by the condensation of 3-formyl-4-hydroxycoumarin and oxalyldihydrazide in the molar ratio 2:1. The Schiff base ligand acts as a mono-, bi-, tri- or even tetradentate ligand with metal cations in the molar ratios 1:1 or 2:1 (M:L) to yield either mono- or binuclear complexes as keto or enol isomers, where M = Co(II), Ni(II), Cu(II), VO(IV), and Fe(III). The ligand and its metal complexes were characterized by elemental analyses, IR, 1H NMR, mass, and UV–Vis spectroscopy. Furthermore, the magnetic moments were calculated from the measured electric conductivities of the complexes. According to the received data, the dihydrazone ligand contains one or two units of ONO domains and can bind to the metal ions via the azomethine nitrogen, the carbonyl oxygen atoms, and/or the phenolic oxygen atoms. Electronic spectra and the magnetic moments of all complexes show that the complexes’ geometries are either octahedral, tetrahedral, square planar, or square pyramidal. Cyclic voltammograms of the mononuclear Co(II) and Ni(II) complexes show quasi-reversible peaks. Tests against two pathogenic bacteria as Gram-positive and Gram-negative bacteria for both, the Schiff base ligand and its metal complexes were carried out. In addition, also one kind of fungi was tested. The synthesized complexes demonstrate mild antibacterial and antifungal activities against these organisms.Graphical abstract Electronic supplementary materialThe online version of this article (doi:10.1007/s00706-017-2075-9) contains supplementary material, which is available to authorized users.

Synthesis of novel VO (II)‐thaizole complexes; spectral, conformational characterization, MOE‐docking and genotoxicity

“…Hydrazone compounds are primarily a Schiff‐base group of materials having a secondary amine proton including a gorgeous family of derivatives in a variance of research areas, such as chemical and biosensors, nonlinear optics, and a variety of medical applications . Moreover, hydrazones are well known to exhibit a great ability to form highly stable complexes with several transition metals . For examples, complexes of hyrazones with VO (II), Zn (II), Cu (II), Ni (II), and Co (II) were recently reported as displaying good antibacterial activities .…”

“…form highly stable complexes with several transition metals. [5,6] For examples, complexes of hyrazones with VO (II), Zn (II), Cu (II), Ni (II), and Co (II) were recently reported as displaying good antibacterial activities. [7,8] Also, other hydrazones complexes with Zn (II), Cu (II), and Ni (II) showed high antifungal activities.…”

Coordination behaviour, molecular docking, density functional theory calculations and biological activity studies of some transition metal complexes of bis‐Schiff base ligand

“…The azomethine nitrogen ν(CH═N) stretching vibration was found in the spectrum of free ligand at 1561 cm −1 . The shift to higher or lower wavenumbers of this peak in the spectra of the complexes (1539–1597 cm −1 ) indicates the azomethine nitrogen participated in coordination . The peaks found at 1630 and 687 cm −1 in the spectrum of the free ligand assigned to the C═N stretching vibration of pyridine was shifted to higher or lower wavenumbers in the spectra of complexes at 1625–1633 and 620–698 cm −1 .…”

Biological evaluation, molecular docking, DNA interaction and thermal studies of new bioactive metal complexes of 2‐hydroxybenzaldehyde and fluorobenzamine Schiff base ligand

“…The electronic transitions of complex 2 at 15,698 ( ν 1 ), 20,790 ( ν 2 ) and 23,980 cm −1 ( ν 3 ) correspond to ‘ 6 A 1g (S) → 4 T 1g (G), 6 A 1g (S) → 4 T 2g (G) and 6 A 1g (S) → 2 T 2g (D)’ transitions, respectively, which implies that the complex possesses a high spin configuration with octahedral geometry [ 54,55 ] and is further confirmed by ν 2 / ν 1 = 1.324, which is close to the octahedral structure value. A moderate band at 37,735 cm −1 shows the presence of L → M charge transfer transitions.…”