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Journal ArticleDOI: 10.1016/J.MOLSTRUC.2020.129525

Polymer complexes. LXXIV. Synthesis, characterization and antimicrobial activity studies of polymer complexes of some transition metals with bis-bidentate Schiff base

05 Mar 2021-Journal of Molecular Structure (Elsevier)-Vol. 1227, pp 129525
Abstract: Copper(II), cobalt(II), nickel(II), manganese(II) and cadmium(II) polymer complexes of N,N`-1,4-phenylene (2-hyboxynaphthaliden imine) have been synthesized. The structure of Schiff base and polymer complexes have been characterized by elemental analysis, spectral (FT-IR, UV–Vis, 1H NMR and ESR), X-ray diffraction, magnetic moment measurements and molar conductance. The molar conductivity data indicates that the chelates are non-electrolytes for polymer complexes (1, 4 & 5). The analytical data support 1:1 (M:L) stoichiometry. FT-IR data shows the ligand function as bis-bidentate coordination through ON NO donor system. The electronic spectra along with magnetic data suggest octahedral geometry for polymer complexes. The XRD patterns of the ligand and its polymer complexes showed the polycrystalline natures. The ligand and its complexes were studied for their microbial activity against some bacteria and fungi. Our results indicated that ligand and polymer complex (3) have higher effect against S. aureus than that of penicillin by at least nine times; this effect increased by increasing the concentration. Molecular docking was used to predict the binding between ligand and two receptors of the crystal structure of Staphylococcus aureus (3q8u) and the crystal structure of E. coli (3t88). It was found that, the receptor of Staphylococcus aureu (3q8u) shows the best interaction than the receptor of E. coli (3t88) with the ligand.

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Topics: Denticity (56%), Ligand (55%), Octahedral molecular geometry (55%) ... show more
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11 results found


Journal ArticleDOI: 10.1016/J.MOLSTRUC.2021.130481
Adel Z. El-Sonbati1, N.F. Omar1, Mohamed I. Abou-Dobara1, M.A. Diab1  +4 moreInstitutions (2)
Abstract: A novel bis-bidentate azo dye ligand, formed by the diazotized reaction of 1,4-diaminobenzene and 8- hydroxyquinoline in 1:2 M ratio resulted the formation of 5,5′-{(1E, 1E`)-1,4-phenylenebis(diazene-2,1-diyl)}bis(quinoline-8-ol) (H2L1) as primary ligand and its Cu(II), Ni(II), Co(II), Mn(II), Cr(III), UO2(II) and Cd(II) complexes. Incorporating of 8-hydroxyquinoline (HL2) as co-ligand with the formed mixed-ligand complexes of the composition, [M2(L1)(L2)2(OH2)4] (M = Cu(II), Co(II), Ni(II), Mn(II), UO2(II), Cd(II) and [Cr2(L1)(L2)2(OH2)2(Cl2)] were synthesized and characterized. H2L1, HL2, and their mixed ligand complexes were screened against two local gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and three local gram-negative bacteria (Klebsiella pneumoniae Escherichia coli and Pseudomonas sp). Antifungal activities were determined against Fusarium oxysporum Aspergillus niger, and Candida albicans. Cr(III), Mn(II) and UO2(II) mixed ligand complexes showed higher activity than H2L1 and HL2; their cytological effects on S. aureus and B. cereus along with the in-silico docking showed that these complexes represent antibacterials targeting FtsZ and DltA proteins; hence, affect cell divisions and gram-positive cell walls. The XRD patterns of the Mn(II) and UO2(II) mixed ligand complexes are polycrystalline natures.

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Topics: Ligand (51%)

7 Citations


Journal ArticleDOI: 10.1007/S13738-021-02354-1
Abstract: Metal complexes of Schiff base 4-[(2, 4-dihydroxy-benzylidene)-amino]-1, 5-dimethyl-2-phenyl-1, 2-dihydroxo-pyrazol-3-one (H2L) derived from condensation of 2,4-dihydroxybenzaldehyde and 4-aminoantipyrine were synthesized and characterized by FT-IR spectra, elemental analysis, 1H &13C NMR, mass spectra, UV–Visible, X-ray diffraction, molar conductance, magnetic moment and thermal analysis (TGA). The elemental analysis proved that the complexes have the general formulae of [M(HL)(X)(OH2)]2, where M = Cu(II); X = OAc− (1); NO3− (2); Cl− (3), M = Co(II) (4), Mn(II) (5); X = OAc and {[UO2(HL)]2.2(OAc)}(6). According to the FT-IR spectra data, it was found that the H2L ligand is coordinated to the metal ions in a tridentate donor sites of the nitrogen atom of azomethine group, the oxygen atom of phenolic group and the oxygen atom of carbonyl group. From the measurements of magnetic susceptibility and electronic spectral data, it is found that these complexes are octahedral geometries. The trend in g value (g║ ˃ g⊥ ˃ 2.00) suggests that the unpaired electron on copper has dx2-y2 character and the complexes have an octahedral structure. By comparing the synthesized ligand (H2L) to its metal complexes was screened for their antibacterial activity against Klebsiella pneumoniae, Escherichia coli, Pseudomonas sp., Bacillus cereus and Staphylococcus aureus. It was found that the metal complexes had more potent antimicrobial than the parent Schiff base ligand against one or more microbial species. Some complexes showed higher activity than ligand. The complex (3) has antibacterial activities against Bacillus cereus, Klebsiella pneumoniae and Staphylococcus aureus. The antibacterial activity of complex (3) was the highest ones than the ligand and other complexes as well as penicillin G against Klebsiella pneumoniae. Antifungal activities were determined against Fusarium oxysporum, Aspergillus niger and Candida albicans. The inhibition efficiency of the prepared ligand (H2L) against the corrosion of carbon steel in HCl (2 M) solution was determined by various electrochemical techniques.

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Topics: Ligand (53%), Schiff base (52%)

1 Citations


Journal ArticleDOI: 10.1016/J.MOLSTRUC.2021.131498
Adel Z. El-Sonbati1, M.A. El-Mogazy1, S.G. Nozha, M.A. Diab1  +3 moreInstitutions (2)
Abstract: Mixed ligand complexes of Cu(II), Co(II), Ni(II), Mn(II) and Cd(II) with N,N'-1,4-phenylene (2-hyboxynaphthaliden imine) (H2L) as primary ligand and 4-aminoantipyrine (4-AAp) as secondary ligand have been prepared. The newly formed complexes were characterized using elemental analysis, magnetic susceptibility, molar conductance, 1H NMR, UV–Vis., FTIR, X-ray diffraction, mass, thermal analysis and ESR techniques. The elemental analysis, data reveal the formation of [2:1:2] [M: H2L: 4-AAP] complexes. The mode of bonding between Cu(II), Ni(II), Co(Il), Mn(II) and Cd(II) and ligands has been studied by IR spectrophotometry. Electronic absorption spectra and magnetic moment measurements of the mixed-ligand complexes suggest a distorted octahedral geometry around the central metal ion and the anions X− are in the axial positions, for all compounds. The ligands are found to behave in a neutral bidentate manner, through nitrogen atom and oxygen atom of carbonyl group (secondary ligand), whereas H2L (primary ligand) coordinated through nitrogen and OH group as a neutral ligand. FT-IR spectral data shows that the ligand acted as bis-bidentate coordination through ON–NO donor system. The XRD patterns of the ligand and its mixed ligand complexes showed the polycrystalline natures. The ligand and its mixed complexes were studied for their microbial activity against some bacteria and fungi. The ligand in comparison to its mixed ligand complexes (1-5) was screened for their antibacterial activity against Klebsiella pneumoniae, Escherichia coli, Pseudomonas sp., Staphylococcus aureus and Bacillus cereus. Antifungal activities of ligand in comparison to its mixed ligand complexes (1-5) were determined against Fusarium oxysporum, Aspergillus niger and Candida albicans. It was found that the mixed ligand complex (5) is more active than other mixed ligand complexes and penicillin G against Bacillus cereus, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas sp. The mixed ligand complex (5) is more active than the ligand and other mixed ligand complexes and miconazole against Aspergillus niger. The inhibition efficiency of the prepared ligand (H2L) against the corrosion of P355 carbon steel in HCl (2 M) solution was determined by various electrochemical methods are found to be in reasonable agreement. The morphology of protected P355 carbon steel was test by energy dispersive X-ray and scanning electron microscope (EDX–SEM).

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Topics: Denticity (63%), Ligand (61%), Octahedral molecular geometry (57%)

Journal ArticleDOI: 10.1016/J.INOCHE.2021.108850
Abstract: A new thiosemicarbazone based ligand synthesized by the facile condensation reaction of 3-ethoxy salicylaldehyde and 4-phenylthiosemicarbazide. Ni(II) complex prepared by the further reaction of thiosemicarbazoneligand with bis(triphenylphosphine)nickel(II) dichloride and formed complex has the chemical formula of [Ni(PPh3)(L)].1H NMR, FT-IR, UV–Visible and single crystal X-ray diffraction techniques were used to characterize the ligand and Ni(II) complex. The findings indicated that the proposed structural framework of Ni(II) complex is distorted tetrahedral geometry.Antibacterial activities of ligand and Ni(II) complex validated against three different bacteria such as Staphylococci aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa)and Escherichia coli (E. coli) by agar well diffusion method. The results revealed that Ni(II) complex has better antibacterial activities than the ligand. The in vitro cytotoxic activities of the ligand and Ni(II) complex were studied on human breast cancer cell lines (MCF-7) by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay.The result showed that ligand and Ni(II) complexes possess significant anticancer ability against the MCF-7 cancer cell lines. Molecular docking of testing compounds with Human Serum Albumin(HSA) and Deoxy ribonucleic acid(DNA) was investigated.The obtained atomic contact energy (ACE)values suggested that Ni(II) complex had a better interacting ability with HSA and DNA molecules than ligand. Based on the molecular docking results, the prepared compounds can interact with DNA through a minor groove mode. The overall results suggested that, the prepared Ni(II) complex would be act as potent anticancer agent with significant targeting efficacy.

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Topics: Ligand (biochemistry) (53%)


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01 Jan 1964-Nature
Abstract: THE use of thermogravimetric data to evaluate kinetic parameters of solid-state reactions involving weight loss (or gain) has been investigated by a number of workers1–4. Freeman and Carroll2 have stated some of the advantages of this method over conventional isothermal studies. To these reasons may be added the advantage of using one single sample for investigation. However, the importance of procedural details, such as crucible geometry, heating rate, pre-history of sample, and particle size, on the parameters has yet to be fully investigated. It is also necessary to ensure accurate temperature measurement, both for precision and also to detect any departure from a linear heating rate due to endo- or exo-thermic reactions. (The effect of these may be largely eliminated by the use of small samples.) In our present work (using a Stanton HT–D thermobalance) the sample temperature is measured directly by means of a thermocouple the bead of which is positioned in or near the sample, depending on crucible design, the wires of which run down a twin-bore rise rod. The connexion between the end of the thermocouple wires on the balance arm and the terminal block is made by 0.001 in. platinum and platinum/rhodium wires5. It has been shown that these wires do not affect the performance of the balance but act merely as a subsidiary damping. From the terminal block compensated cable leads to the cold junction and a potentiometric arrangement for direct measurement of the thermocouple output.

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Topics: Thermocouple (54%)

5,308 Citations


Open accessJournal ArticleDOI: 10.1006/ABIO.1999.4019
Pilar Prieto1, Manuel Pineda1, Miguel Aguilar1Institutions (1)
Abstract: A spectrophotometric method has been developed for the quantitative determination of antioxidant capacity. The assay is based on the reduction of Mo(VI) to Mo(V) by the sample analyte and the subsequent formation of a green phosphate/Mo(V) complex at acidic pH. The method has been optimized and characterized with respect to linearity interval, repetitivity and reproducibility, and molar absorption coefficients for the quantitation of several antioxidants, including vitamin E. The phosphomolybdenum method, in combination with hexane monophasic extraction, has also been adapted for the specific determination of vitamin E in seeds. The results obtained with the proposed method were validated by comparison with a standard HPLC method. The phosphomolybdenum method is routinely applied in our laboratory to evaluate the total antioxidant capacity of plant extracts and to determine vitamin E in a variety of grains and seeds, including corn and soybean.

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Topics: Metal chelating activity (50%), Vitamin E (50%)

3,916 Citations


Book ChapterDOI: 10.1007/430_022
Guillem Aromí1, Euan K. BrechinInstitutions (1)
26 Jan 2006-ChemInform

1,918 Citations



Open accessBook
01 Jan 1971-
Abstract: The Science of Large Molecules POLYMERIZATION Step-Reaction (Condensation) Polymerization Radical Chain (Addition) Polymerization Ionic and Coordination Chain (Addition) Polymerization Copolymerization Polymerization Conditions and Polymer Reactions CHARACTERIZATION Polymer Solutions Measurement of Molecular Weight and Size Analysis and Testing of Polymers STRUCTURE AND PROPERTIES Morphology and Order in Crystalline Polymers Rheology and the Mechanical Properties of Polymers Polymer Structure and Physical Properties PROPERTIES OF COMMERICAL POLYMERS Hydrocarbon Plastics and Elastomers Other Carbon-Chain Polymers Heterochain Thermoplastics Thermosetting Resins POLYMER PROCESSING Plastics Technology Fiber Technology Elastomer Technology Appendixes Author and Subject Indexes.

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Topics: Polymerization (69%), Fire-safe polymers (68%), Chain transfer (67%) ... show more

1,701 Citations