Ahmed M.M. Hindy

Coordination behavior of new bis Schiff base ligand derived from 2-furan carboxaldehyde and propane-1,3-diamine. Spectroscopic, thermal, anticancer and antibacterial activity studies.

Novel bis Schiff base ligand, [N1,N3-bis(furan-2-ylmethylene)propane-1,3-diamine], was prepared by the condensation of furan-2-carboxaldehyde with propane-1,3-diamine. Its conformational changes on complexation with transition metal ions [Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II) and Fe(III)] have been studied on the basis of elemental analysis, conductivity measurements, spectral (infrared, (1)H NMR, electronic), magnetic and thermogravimetric studies. The conductance data of the complexes revealed their electrolytic nature suggesting them as 1:2 (for bivalent metal ions) and 1:3 (for Fe(III) ion) electrolytes. The complexes were found to have octahedral geometry based on magnetic moment and solid reflectance measurements. Thermal analysis data revealed the decomposition of the complexes in successive steps with the removal of anions, coordinated water and bis Schiff base ligand. The thermodynamic parameters were calculated using Coats-Redfern equation. The Anticancer screening studies were performed on human colorectal cancer (HCT), hepatic cancer (HepG2) and breast cancer (MCF-7) cell lines. The antimicrobial activity of all the compounds was studied against Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Bacillus vulgaris and Staphylococcus pyogones) bacteria. It was observed that the coordination of metal ion has a pronounced effect on the microbial activities of the bis Schiff base ligand. All the metal complexes have shown higher antimicrobial effect than the free bis Schiff base ligand.

Thermal and spectroscopic investigation of novel Schiff base, its metal complexes, and their biological activities

AbstractThe complexing behavior of H2L ((N,N’Z,N,N’E)-N,N’-(ethane-1,2-diylbis(oxy)bis(2,1-phenylene)bis(methanylylidene)bis(1-hydrazinylmethanethioamide)) toward the transition metal ions namely Fe(III), Co(II), Ni(II), Cu(II), Cd(II), and Zn(II) have been examined by elemental analyses, magnetic measurements, electronic, IR, and 1H-NMR. Thermal properties and decomposition possibilities of all complexes are suggested. The interpretation of all thermal decomposition stages has been evaluated. The free ligand and its metal complexes have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillus subtilis, and Staphylococcus aurous bacteria in order to assess their antimicrobial potential. The results indicate that the metal complexes are also found to have more antimicrobial activity than the parent ligand.Graphical AbstractThe proposed structure of complexes. Novel Schiff base and its metal complexes were prepared and characterized based on elemental analyses, IR, 1H-NMR, magnetic moment, molar conductance, and thermal analyses techniques. Complexes of 1:1 [Metal]:[Ligand] ratio for Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) are formed. They are electrolytes in which ligand coordinated to the metal ions in a uni-negative hexa-dentate manner with O2N2 donor sites of the etheric O, and azomethine N atoms and have octahedral geometry.

Transition metal complexes of novel Schiff base

New metal(II)/(III) complexes with novel Schiff base, resulted from the condensation of propane-1,3-diamine with bisaldehyde, as tetradentate ligand have been synthesized and characterized using elemental analyses, spectra (IR, 1H NMR and ESR), molar conductance, magnetic moment, and thermal studies. The IR data suggest the coordination mode for the Schiff base ligand which behaves as a tetradentate with the metal ions. Based on the elemental analysis, magnetic studies, electronic, and ESR data, octahedral geometry was proposed for the complexes. The ESR spectra of the Cu(II) complex in powdered form showed an axial symmetry with 2B1g as ground state and hyperfine structure. The thermal stability and degradation of the Schiff base ligand and its metal complexes were studied by TG. The molar conductance in DMF solution indicates that all complexes are electrolytes. The free Schiff base ligand and its metal complexes were tested for their in vitro antimicrobial activity against gram-positive and gram-negative organisms. The results showed that the synthesized complexes exhibited higher antimicrobial activity than their free Schiff base ligand. Of all the studied complexes, the Cu(II) and Co(II) complexes exhibited high antimicrobial activity at low micromolar inhibitory concentrations compared to the other complexes, amikacin standard, and the free Schiff base ligand.

Preparation of macrocyclic Schiff-base ligand and antibacterial activities of transition metal complexes thereof

A macrocyclic Schiff-base (H2L) ligand is prepared via condensation of 2,6-pyridine dicarboxaldehyde with triethylene tetramine. The ligand is characterized using elemental analysis, by mass spectrometry, infrared (IR) spectroscopy, and proton nuclear magnetic resonance spectroscopy. The corresponding 1:1 metal complexes with Cr(III), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), UO2(II), and Th(IV) are additionally characterized by determining their magnetic moment, molar conductance, thermal analysis (thermogravimetry and differential thermoanalysis), and solid reflectance measurements. The complexes have the general formulae [M(H2L)(H2O)](X) n · yH2O (X = Cl or AcO, n = 2,3, y = 2–5) except for the Th(IV) complex having the formula [Th(H2L)(Cl)]Cl3. The molar conductance data reveal that all the metal chelates are electrolytes. IR spectra show that H2L is coordinated to the metal ions in a neutral pentadentate manner with 5N donor sites of the two azomethine–N, pyridine–N, and two amino–NH groups. The magnetic and solid reflectance spectra reveal that the complexes are octahedral. Thermal analysis shows that the complexes decompose in four to five steps. The activation thermodynamic parameters are calculated using the Coats–Redfern method. The parent Schiff base and its eight metal complexes were assayed against four bacterial species, two Gram negative, and two Gram positive. The Schiff base and five of its metal complexes showed antibacterial activity at different rates. The complexes Cr(III) and Cu(II) inhibited Gram-positive bacteria, while Co(II) complex inhibited all tested bacteria greater than the parent Schiff base. Three metal complexes (Ni, Cd, and Th) completely missed antibacterial activity.