Cu(II) Complexes of 4-[(1E)-N-{2-[(Z)-Benzylidene-amino]ethyl}ethanimidoyl]benzene-1,3-diol Schiff Base: Synthesis, Spectroscopic, In-Vitro Antioxidant, Antifungal and Antibacterial Studies

Abstract

The current study reports the synthesis of copper complexes of a tridentate Schiff base ligand. The compounds of the type [Cu(L)X]∙n(H2O) (where L = tridentate ONN Schiff base ligand, X = Cl−, Br−, SCN−, NO3−, CH3COO−), were characterized on the basis of elemental analyses, FT-IR, UV-vis, molar conductance, 1H-NMR, XRD and thermal analyses. The spectra revealed that the Schiff base ligand acts as a tridentate ligand through two azomethine nitrogen atoms and a phenolic oxygen atom. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature. TGA and DTA studies results gave insight into the dehydration, thermal stability, and thermal decomposition. Square-planar geometry has been assigned to the prepared complexes as indicated by the electronic spectral measurements. Cu(II) compounds showed antiradical potential against DPPH and ABTS radicals. The antimicrobial potential of the Schiff base ligand and its Cu(II) complexes were evaluated by the rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay against some selected bacteria strains: Staphylococcus aureus and Enterococcus faecalis (Gram +ve); Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram −ve), and fungi (Candida albicans and Cryptococcus neoformans). The compounds showed a broad spectrum of antibacterial and antifungal activities, with MIC values ranging from 48.83 to 3125 μg/mL.

Schiff Bases and their Copper(II) Complexes Derived from Cinnamaldehyde and Different Hydrazides: Synthesis and Antibacterial Properties

“…The results demonstrate a formula of either 2 mol of bidentate hydrazone Schiff base ligands coordinate to 1 mol of copper(II) ion involving L 1 and L 2 , while 3 mol of L 3 Schiff base ligands coordinate to 1 mol of copper(II) 1 3,531 1,675 1,494 L 2 3,243 1,651 1,491 L 2 3,528 1,675 1,493 L 3 3,341 1,670 1,445 L 3 3,508 1,677 1,494 ion; as shown in Table 2. The proposed structures of Schiff base metal complexes are shown in Figure 3 and found to be comparable with some previously reported complexes involving copper(II) ion and hydrazones [30,31,32]. We predict that the metal complexes were obtained from the chelation of the ligands through the N and O atoms, forming stable five-membered chelate ring along with deprotonation of amine hydrogen atoms.…”

“…This is presumably due to the intramolecular hydrogen bonding within the molecule. The appearance of new bands in the low-frequency infrared region (< 1, 000 cm −1 ) between 520 cm −1 and 557 cm −1 is attributed to υ Cu−N ; while the bands within the region of 483-625 cm −1 are assigned to υ Cu−O [30,33]. These pieces of evidence confirmed that the ligands are coordinated to the copper(II) ion via the imine nitrogen atom and carbonyl oxygen atom albeit this region has been more difficult to assess.…”

Gc-MS Analysis and Extraction Optimization of Bioactive Compounds From Pelargonium Graveolens Lher Methanolic Extract and Their Activities as Pharmacological Agents

“…However, the efficient activity againstABTS •+ and weak anti-DPPH radical activity is evocative of a substitute scavenging mechanism of the methanol extract of P. graveolens. This is further supported by the fact that most scavenging processes are accomplished either by electron or proton donation to unstable radical, as reported by various studies 18,20 .…”

“…Minimum inhibitory concentrations (MIC) of extracts for antibacterial activity were determined using the micro dilution bioassay as described [19][20] . Overnight cultures (incubated at 37°C in a water bath with an orbital shaker) of two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and two Gram-negative (Escherichia coli and Salmonella typhi) bacterial strains were diluted with sterile Mueller-Hinton (MH) broth to give final inoculums of approximately 10 6 CFU/ml (colony forming units).…”

“…The plates were covered with para film and incubated at 37°C for 24 h. Bacterial growth was observed by adding 50 µl of 0.2 mg/ml p-iodonitrotetrazolium chloride (INT) (Sigma-Aldrich, Germany) and further incubation at 37°C for 24 h. Since the colorless tetrazolium salt was reduced biologically to a red product due to the presence of active organisms, the MIC values were determined as the concentrations in the last wells in which no color change was observedafter adding the INT indicator. A reddish-pink color indicated bacterial growth 20 .…”