Synthesis, Structure, and Biological Activity of Some Transition Metal Complexes with the Mixed Ligand of Metformin and 1,4-Diacetylbenzene

Abstract

Mononuclear complexes of Co(II), Ni(II), Cu(II), Zr(IV), Pd(II), and Cd(II) with metformin hydrochloride (MF) and 1,4-diacetylbenzene (DAB) have been synthesized, and their structures have been elucidated on the basis of FT-IR, 1 H NMR, and electronic spectra, molar conductance, magnetic susceptibility measurements, thermal, and elemental analysis. Molar conductance measurements indicate electrolytic nature of the complexes. According to FT-IR spectra, MF reacts with metal ions as a bidentate ligand through its two imino groups, and DAB reacts as a monodentate ligand through one of two equivalent keto groups. The complexes have octahedral structure, except Pd(II) complex which is square planar. TGA and DTG analyses support the suggested stereochemistry and subsequently the proposed mechanism of thermal decomposition. Coats-Redfern and Horowitz-Metzger equations have been used for calculating kinetic and thermodynamic parameters of the main decomposition step. Molecular modeling calculations confi rm the structure of the complexes. The ligands and their complexes in vitro antimicrobial activity tests against some bacterial and fungal strains indicate higher activity of the complexes than that of MF and DAB.

Structural elucidation, molecular modeling, and biological and antioxidant studies of phenanthroline/nicotinamide metals complexes

“…[9] New signals were detected in the range of 3.37-3.95 ppm in the 1 H-NMR spectra of the complexes, owing to the presence of water molecules in the complexes. [28] Thus, the 1 H-NMR result supports the geometry assigned.…”

“…M) CT from the electronic lone pairs of adjacent nitrogen or oxygen coordinated to the metal ions. [12,[22][23][24][25][26][27][28] The electronic spectrum of Co (II) complex showed two d-d transitions bands at 578, 625 nm attributed to T 1g (F) ! 4 A 2g (F) and 4 T 1g (F) !…”

“…The 1 H-NMR spectrum shows a signal assigned to (s,2H,-NH 2 ) amine protons at δ:7.50 ppm and a multiple signal assigned to aromatic ring protons at δ: 7.57, 8.22, 8.70 ppm. Phen's 1 H-NMR spectrum revealed peaks for the protons of the aromatic ring [12,[24][25][26][27][28] in the range δ: 7.26, 7.77, 8.11 ppm. The 1 H-NMR spectra of NA and Phen ligands have a signal at δ: 9.03 and 8.81 ppm assigned to (s,H,CH=N).…”

Ligational and biological studies of Fe(III), Co(II), Ni(II), Cu(II), and Zr(IV) complexes with carbamazepine as antiepileptic drug

“…The coordination sites involved in chelating were seen in the comparison of the complexes' FT‐IR spectra with those of the CBZ ligand. [ 29–32 ] In the IR spectra of the complexes, the band corresponding to the (C=O) amide shifted to higher frequency (7–12 cm −1 ) or lower frequency (8 cm −1 ), which indicate the participation of the amide moiety's C=O with the metal ions. [ 33 ] Also, the band of amino group (NH 2 ) is shifted to higher and lower values in all complexes Table 2, which is a good indication that the nitrogen coordinated with metal ions.…”

Synthesis, crystal structures, DNA interactions, and antitumor activity of two new dinuclear copper(ii) complexes with thiazole ligand

“…30 The selection of ligand plays an important role in the biological activity of complexes. 31 Thiazole derivatives, due to their electron donation properties with their nitrogen-containing heterocyclic, are commonly used as dinuclear 32,33 or mononuclear 34 ligands to synthesize multi-functional thiazole metal complexes with transition metal. 35,36 Thiazole metal complexes are widely used in medicine, 37 optical materials, 38 and agriculture.…”