Synthesis, characterization and antibacterial properties of some transition metal complexes of (1H-pyrrol-2-yl)-isonicotinoylhydrazone

Abstract

ABSTRACT.A new ligand, (1H-pyrrol-2-yl)isonicotinoylhydrazone (Pyr-inh) and its metal complexes have been synthesised and characterized by elemental analyses, IR, 1 H and 13 C-NMR, UV-Vis spectra, molar conductance, and thermogravimetry-differential thermal analysis (TG-DTA). From the results obtained, the structure of the complexes are of general formula [M(Pyr-inh)2Cl2].xH2O for M = Co(II), and Zn(II) and [M(Pyrinh)2(H2O)2]Cl2 for Cu(II). The thermal behaviour of these complexes showed the loss of lattice water in the first step followed by decomposition of the ligand in subsequent steps. The ligand and its transition metal complexes were studied for their in vitro antibacterial activity against ten pathogenic bacterial strains. The data obtained revealed that the ligand was active against Morganella morganii and Escherichia coli, the Co(II) complex active against Klebsiella oxytoca, the Cu(II) complex showed significant activity against five out of the ten bacterial strains and the Zn(II) complex was active against all the pathogenic bacterial strains investigated.

Synthesis and Crystal Structure of Bis(N’-(Pyridine-3-Carboxaldehyde) Isonicotinoylhydrazone) Zinc(II)

“…We have isolated a metal-organic framework from a pyridine-containing heterocyclic Schiff base ligand. The 1 H-NMR and 13 C-NMR spectra of this zinc(II) complex, show the symmetric nature of the complex in which the Schiff base is coordinated to the zinc atom through the pyridine nitrogen, thus forming a head-on, N-Zn-N system. This is confirmed by the X-ray structure of the complex.…”

“…Therefore, all these observations fit and confirm the model where the zinc atom binds through the nitrogen atom of the pyridine, and where the imine group does not participate in bonding. (17,13) 124.04 (5) 129.93 3133.64 (4) 140.26 (12) 146.34 7148.87 (2) 150.34 (14,16) 150.97 (6) 161.78(10) The IR spectrum of the ligand (L) and that of the ZnL 2 complex show a broad peak at 3237 cm −1 attributed to υ(O-H) of water molecules in the complex which is clearly absent in the spectrum of the ligand (Figure 3). The peak at 3183 cm −1 corresponds to υ(N-H) stretching of the ligand.…”

“…Schiff bases are important as ligands because of their ease of preparation and their resemblance to natural biomolecules [8] [9]. Their metal complexes have been studied extensively because of their attractive physico-chemical properties and structural diversity, which account for their wide range of applications in industry and biology [9]- [13]. Zinc complexes of Schiff base ligands have received particular attention due to their ease of preparation, high thermal stability, photoluminescence properties and their potential applications as catalysts and model molecules for biochemical systems [10] [12] [14].…”

“…Our group recently embarked on studies on the biological activities of complexes of heterocyclic Schiff base ligands [13] [18]. The observed biological activities result from the presence of the characteristic azomethine (-N=CH-) functionality of the Schiff base.…”

Synthesis, characterization and antimicrobial activities of heteroleptic metal chelates of isoniazid and 2,2’-bipyridine

“…The results showed that the ligands exhibited low antibacterial activity except for 2,2-bipyridine. The increased activity of the metal complexes may be attributed to an increase in their lipophilicity, which facilitates their absorption through the lipid bilayer of the microorganism [24,25]. The metal complexes undertake their action on the micro-organisms through several ways, but particularly earlier reports on isoniazid have revealed that the complexes undergo dissociation once inside the cell thus releasing the cytotoxic ligands [26].…”