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Syntheses, characterization, and biological activity of novel mono- and binuclear transition metal complexes with a hydrazone Schiff base derived from a coumarin derivative and oxalyldihydrazine.

ABSTRACT: Abstract:A hydrazone Schiff base ligand was synthesized by the condensation of 3-formyl-4-hydroxycoumarin and oxalyldihydrazide in the molar ratio 2:1. The Schiff base ligand acts as a mono-, bi-, tri- or even tetradentate ligand with metal cations in the molar ratios 1:1 or 2:1 (M:L) to yield either mono- or binuclear complexes as keto or enol isomers, where M = Co(II), Ni(II), Cu(II), VO(IV), and Fe(III). The ligand and its metal complexes were characterized by elemental analyses, IR, 1H NMR, mass, and UV-Vis spectroscopy. Furthermore, the magnetic moments were calculated from the measured electric conductivities of the complexes. According to the received data, the dihydrazone ligand contains one or two units of ONO domains and can bind to the metal ions via the azomethine nitrogen, the carbonyl oxygen atoms, and/or the phenolic oxygen atoms. Electronic spectra and the magnetic moments of all complexes show that the complexes' geometries are either octahedral, tetrahedral, square planar, or square pyramidal. Cyclic voltammograms of the mononuclear Co(II) and Ni(II) complexes show quasi-reversible peaks. Tests against two pathogenic bacteria as Gram-positive and Gram-negative bacteria for both, the Schiff base ligand and its metal complexes were carried out. In addition, also one kind of fungi was tested. The synthesized complexes demonstrate mild antibacterial and antifungal activities against these organisms. Graphical abstract:

SUBMITTER: Knittl ET

PROVIDER: S-EPMC5818636 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Syntheses, characterization, and biological activity of novel mono- and binuclear transition metal complexes with a hydrazone Schiff base derived from a coumarin derivative and oxalyldihydrazine.

Knittl Esther Theresa ET Abou-Hussein Azza A AA Linert Wolfgang W

Monatshefte fur chemie 20171127 2

<h4>Abstract</h4>A hydrazone Schiff base ligand was synthesized by the condensation of 3-formyl-4-hydroxycoumarin and oxalyldihydrazide in the molar ratio 2:1. The Schiff base ligand acts as a mono-, bi-, tri- or even tetradentate ligand with metal cations in the molar ratios 1:1 or 2:1 (<i>M</i>:<i>L</i>) to yield either mono- or binuclear complexes as keto or enol isomers, where <i>M</i> = Co(II), Ni(II), Cu(II), VO(IV), and Fe(III). The ligand and its metal complexes were characterized by ele ...[more]

PMID: 29497214

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Project description:BackgroundThe oxidative transformation of benzoin to benzil has been accomplished by the use of a wide variety of reagents or catalysts and different reaction procedures. The conventional oxidizing agents yielded mainly benzaldehyde or/and benzoic acid and only a trace amount of benzil. The limits of practical utilization of these reagents involves the use of stoichiometric amounts of corrosive acids or toxic metallic reagents, which in turn produce undesirable waste materials and required high reaction temperatures.In recent years, vanadium complexes have attracted much attention for their potential utility as catalysts for various types of reactions.ResultsActive and selective catalytic systems of new unsymmetrical oxovanadium(IV) Schiff base complexes for the oxidation of benzoin is reported. The Schiff base ligands are derived between 2-aminoethanol and 2-hydroxy-1-naphthaldehyde (H2L1) or 3-ethoxy salicylaldehyde (H2L3); and 2-aminophenol and 3-ethoxysalicylaldehyde (H2L2) or 2-hydroxy-1-naphthaldehyde (H2L4). The unsymmetrical Schiff bases behave as tridentate dibasic ONO donor ligands. Reaction of these Schiff base ligands with oxovanadyl sulphate afforded the mononuclear oxovanadium(IV) complexes (VIVOLx.H2O), which are characterized by various physico-chemical techniques.The catalytic oxidation activities of these complexes for benzoin were evaluated using H2O2 as an oxidant. The best reaction conditions are obtained by considering the effect of solvent, reaction time and temperature. Under the optimized reaction conditions, VOL4 catalyst showed high conversion (>99%) with excellent selectivity to benzil (~100%) in a shorter reaction time compared to the other catalysts considered.ConclusionFour tridentate ONO type Schiff base ligands were synthesized. Complexation of these ligands with vanadyl(IV) sulphate leads to the formation of new oxovanadium(IV) complexes of type VIVOL.H2O.Elemental analyses and spectral data of the free ligands and their oxovanadium(IV) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds.Oxovanadium complexes were screened for the oxidation of benzoin to benzil using H2O2 as oxidant. The effect of time, solvent and temperature were optimized to obtain maximum yield. The catalytic activity results demonstrate that these catalytic systems are both highly active and selective for the oxidation of benzoin under mild reaction conditions.

Project description:Metal-based drugs, including lanthanide complexes, have been extremely effective in clinical treatments against various diseases and have raised major interest in recent decades. Hence, in this work, a series of lanthanum (III) and cerium (III) complexes, including Schiff base ligands derived from (1H-benzimidazol-2-yl)aniline, salicylaldehyde, and 2,4-dihydroxybenzaldehyde were synthesized and characterized using different spectroscopic methods. Besides their cytotoxic activities, they were examined in human U-937 cells, primate kidney non-cancerous COS-7, and six other, different human tumor cell lines: U251, PC-3, K562, HCT-15, MCF-7, and SK-LU-1. In addition, the synthesized compounds were screened for in vitro antiparasitic activity against Leishmania braziliensis, Plasmodium falciparum, and Trypanosoma cruzi. Additionally, antibacterial activities were examined against two Gram-positive strains (S. aureus ATCC® 25923, L. monocytogenes ATCC® 19115) and two Gram-negative strains (E. coli ATCC® 25922, P. aeruginosa ATCC® 27583) using the microdilution method. The lanthanide complexes generally exhibited increased biological activity compared with the free Schiff base ligands. Interactions between the tested compounds and model membranes were examined using differential scanning calorimetry (DSC), and interactions with calf thymus DNA (CT-DNA) were investigated by ultraviolet (UV) absorption. Molecular docking studies were performed using leishmanin (1LML), cruzain (4PI3), P. falciparum alpha-tubulin (GenBank sequence CAA34101 [453 aa]), and S.aureus penicillin-binding protein 2a (PBP2A; 5M18) as the protein receptors. The results lead to the conclusion that the synthesized compounds exhibited a notable effect on model membranes imitating mammalian and bacterial membranes and rolled along DNA strands through groove interactions. Interactions between the compounds and studied receptors depended primarily on ligand structures in the molecular docking study.

Project description:A new family of dicopper(I) complexes [CuI2RL](X)2 (R=H, 1X, R=tBu, 2X and R=NO2, 3X, X=CF3SO3, ClO4, SbF6, or BArF, BArF=[B{3,5-(CF3)2C6H3}4]-), where RL is a Schiff-base ligand containing two tridentate binding sites linked by a xylyl spacer, has been prepared and characterized, and its reaction with O2 has been studied. The complexes were designed with the aim of reproducing structural aspects of the active site of type 3 dicopper proteins; they contain two three-coordinate copper sites and a rather flexible podand ligand backbone. The solid-state structures of 1ClO4, 2CF3SO3, 2ClO4, and 3BArF.CH3CN have been established by single-crystal X-ray diffraction analysis. 1ClO4 adopts a polymeric structure in the solid state while 2CF3SO3, 2ClO4, and 3BArF.CH3CN are monomeric. The complexes have been studied in solution by means of 1H and 19F NMR spectroscopy, which put forward the presence of dynamic processes. 1-3BArF and 1-3CF3SO3 in acetone react rapidly with O2 to generate metaestable [CuIII2(mu-O)2(RL)]2+ 1-3(O2) and [CuIII2(mu-O)2(CF3SO3)(RL)]+ 1-3(O2)(CF3SO3) species, respectively, that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reaction of 1-3BArF with O2 in CH2Cl2 results in intermolecular O2 binding. DFT methods have been used to study the chemical identities and structural parameters of the O2 adducts, and the relative stability of the CuIII2(mu-O)2 form with respect to the CuII2(mu-eta2:eta2-O2) isomer. The reaction of 1X, X = CF3SO3 and BArF, with O2 in acetone has been studied by stopped-flow UV-vis exhibiting an unexpected very fast reaction rate (k=3.82(4)x10(3) M-1 s-1, DeltaH=4.9+/-0.5 kJ.mol-1, DeltaS=-148+/-5 J.K-1.mol-1), nearly 3 orders of magnitude faster than in the parent [CuI2(m-XYLMeAN)]2+. Thermal decomposition of 1-3(O2) does not result in aromatic hydroxylation. The mechanism and kinetics of O2 binding to 1X (X=CF3SO3 and BArF) are discussed and compared with those associated with selected examples of reported models of O2-processing copper proteins. A synergistic role of the copper ions in O2 binding and activation is clearly established from this analysis.

Dataset Information

Syntheses, characterization, and biological activity of novel mono- and binuclear transition metal complexes with a hydrazone Schiff base derived from a coumarin derivative and oxalyldihydrazine.

Publications

Syntheses, characterization, and biological activity of novel mono- and binuclear transition metal complexes with a hydrazone Schiff base derived from a coumarin derivative and oxalyldihydrazine.

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