Ali Ourari

Electrocatalytic hydrogenation of ketones and enones at nickel microparticles dispersed into poly(pyrrole-alkylammonium) films

Nickel microparticles have been dispersed in conducting anion-exchange polymer films coated on carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. Incorporation of nickel metal in polymeric films was effected by electroreduction of polymer coated electrodes in aqueous electrolytes containing nickel-oxalate complexes. The metal deposition process was examined by voltamperometry. Scanning electron microscopy showed a dispersion of metal particles with sizes ranging from 700 to 1200 nm. The electrocatalytic hydrogenation of a variety of cyclohexanones and cyclohexenones at these electrode materials was performed with good current and product yields.

Synthesis and characterization of a new Schiff base derived from 2,3-diaminopyridine and 5-methoxysalicylaldehyde and its Ni(II), Cu(II) and Zn(II) complexes. Electrochemical and electrocatalytical studies

We describe the synthesis and characterization of a new tetradentate Schiff base ligand obtained from 2,3-diaminopyridine and 5-methoxysalicylaldehyde. This ligand (H2L) reacted with nickel(II), copper(II), and zinc(II) acetates to give complexes. The ligand and its metal complexes were characterized using analytical, spectral data (UV–vis, IR, and mass spectroscopy), and cyclic voltammetry (CV). The crystal structure of the copper complex was elucidated by X-ray diffraction studies. The electrochemical behavior of these compounds, using CV, revealed that metal centers were distinguished by their intrinsic redox systems, e.g. Ni(II)/Ni(I), Cu(II)/Cu(I), and Zn(II)/Zn(I). Moreover, the electrocatalytic reactions of Ni(II) and Cu(II) complexes catalyze the oxidation of methanol and benzylic alcohol.

Synthesis, Characterization, and Electrochemical Study of Tetradentate Ruthenium-Schiff Base Complexes: Dioxygen Activation with a Cytochrome P450 Model Using 1- or 2-Methylimidazole as Axial Bases

Salicylaldehyde, 2-hydroxyacetophenone, and 3,5-dichlorosalicylaldehyde react with 1,2-diaminoethane to give three symmetrical Schiff bases H2L1, H2L2, and H2L3, respectively. With Ru(III) ions, these ligands lead to three complexes: Ru(III)ClL1 (𝟏), Ru(III)ClL2 (𝟐), and Ru(III)ClL3 (𝟑). The purity of these compounds was estimated by TLC technique and microanalysis while their structures were supported by the usual spectroscopic methods such as NMR, infrared, and electronic spectra. The cyclic voltammetry in acetonitrile showed irreversible waves for all three ligands. Under the same experimental conditions, it was proved that the ruthenium is coordinated in the three complexes 𝟏, 𝟐, and 𝟑 showing quasireversible redox systems. The behavior of these complexes and their comparison with cytochrome P450 are investigated using them as catalysts in the presence of molecular oxygen with an apical nitrogen base: 1- or 2-methylimidazole.

Synthesis and Chelating Properties of Polystyrene Supported Schiff Base (N,N′-disalicylidenepropylenetriamine) Resin Toward Some Divalent Metal Ions

A new polystyrene-supported Schiff base resin, N,N-bis(salicylidenepropylenetriamine)- aminomethyl polystyrene, has been synthesized through a reaction between the commercially available 4-chloromethyl polystyrene polymer and the Schiff base, N,N′-disalicylidenepropylenetriamine. The chelation behavior of this resin toward the divalent metal ions Cu2 +, Ni2 +, Zn2 +, and Pb2 + in aqueous solutions was investigated. Batch equilibration experiments were carried out as a function of contact time, pH, amount of metal-ion, polymer mass, and temperature. The amount of metal-ion uptake of the polymers was determined by using atomic absorption spectrometry (AAS). Results of the study revealed that the resin exhibited higher capacities and a more pronounced adsorption toward Cu2 + and that the metal-ion uptake follows the order: Cu2 + > Zn 2 + > Ni2 + > Pb2+. The adsorption and binding capacity of the resin toward the various metal ions investigated are discussed.

A novel copper(II) complex with an unsymmetrical tridentate-Schiff base: synthesis, crystal structure, electrochemical, morphological and electrocatalytic behaviors toward electroreduction of alkyl and aryl halides

This work describes the synthesis of a new unsymmetrical tetradentate copper(II) Schiff base complex Cu(L)(Py)(ClO4) containing N3O donor atoms. The tridentate ligand (HL) has been prepared by condensation of dehydroacetic acid on 1,2-diaminopropane in methanol. The reaction of the ligand with an appropriate amount of copper(II) perchlorate hexahydrate (1 : 1 ratio) in the same solvent and in the presence of an excess of pyridine (Py) yields the title compound. The tridentate ligand (HL) with pyridine act as mixed ligands where three nitrogen and an enolic oxygen atoms were chelated to the copper centre. This complex has been fully characterized by FT-IR, UV-Vis spectrophotometry, and cyclic voltammetry. Single crystal X-ray diffraction of this complex showed that the copper ion was coordinated by one ligand, one pyridine molecule with one perchlorate anion in a square pyramidal geometry. The Cu(L)(Py)(ClO4) complex crystallizes in an orthorhombic system, space group of cab with a = 11.051, b = 15.58, c = 21.736 A and Z = 8. The electrochemical reduction of the copper(II) complex, in N,N-dimethylformamide (DMF) solvent using cyclic voltammetry, produces conducting polymeric films on different electrode substrates, such as glassy carbon (GC), indium tin oxide (ITO) and fluorine tin oxide (FTO). The catalytic activity of this complex in homogeneous and heterogeneous electrocatalytic media seems to be efficient for the electroreduction of bromocyclopentane and iodobenzene.

Novel nickel(II) and manganese(III) complexes with bidentate Schiff-base ligand: synthesis, spectral, thermogravimetry, electrochemical and electrocatalytical properties

An unsymmetrical bidentate Schiff base ligand, ethane 2-(4-methoxyphenyl)-1-iminosalicylidene, and its novel two mononuclear complexes, Nickel(II) [Ni(II)-2L] and Manganese(III) [Mn(III)Cl-2L] where L represents the ligand, have been synthesized and characterized by various physicochemical methods. The Ni(II) ion is coordinated by two nitrogen and two oxygen atoms with both the bidentate Schiff base ligands in an approximately square planar coordination geometry, while the manganese complex, the Mn(III) ion, is involved in an additional contact with one chloride anion for which the coordination sphere appears as a square pyramidal arrangement. The thermogravimetric analyses of the synthesized compounds revealed three different stages of decomposition for NONO bis-bidentate manganese and nickel complexes. The cyclic voltammetry studies of these complexes in N,N-dimethylformamide showed a redox couple for each one of them, such as Ni(II)/Ni(I) and Mn(III)/Mn(II), which are quasi-reversible. Their catalytic behaviors were tested showing that the nickel complex is an effective electrocatalyst in the reduction of bromocyclopentane. Regarding the manganese complex, it was revealed that it is an efficient catalyst in the activation of molecular dioxygen, currently applied in oxidation reactions of hydrocarbons according to the monooxygenase enzymes as those of cytochrome P450 model.

1-{2-Hy­droxy-6-[3-(pyrrol-1-yl)prop­oxy]phen­yl}ethanone

In the title compound, C15H17NO3, the mean planes of the pyrrole and benzene rings form a dihedral angle of 81.92 (7)°. The molecule contains an intramolecular O—H⋯O hydrogen bond. In the crystal, weak C—H⋯π interactions link the molecules into chains along [010].

2-[({2-[(2-Hy­droxy-5-meth­oxy­benzyl­idene)amino]­eth­yl}imino)­meth­yl]-4-meth­oxy­phenol

The asymmetric unit of the title compound, C18H20N2O4, contains one-half molecule with an inversion center located at the centroid of the molecule. In the crystal, molecules are linked by C—H⋯π interactions, forming layers parallel to (101). An intramolecular O—H⋯N hydrogen bond also occurs.

Aqua­{4,4′-dimeth­oxy-2,2′-[pyridine-2,3-diylbis(nitrilo­methanylyl­idene)]­diphenolato}copper(II)

Molecules of the title compound, [Cu(C21H17N3O4)(H2O)], lie across a crystallographic mirror plane. The CuII atom is five-coordinated in a distorted square-pyramidal environment by two phenolate O atoms and two imine N atoms of the tetradentate Schiff base anion in the basal plane and one water molecule in the apical position. Because of symmetry, the pyridine N atom and the corresponding C atom at the 4-position of the pyridine ring are disordered. The crystal packing can be described as being composed of alternating layers stacked along [001]. Intramolecular C—H⋯N and intermolecular C—H⋯O and O—H⋯O hydrogen-bonding interactions, as well as C—H⋯π and π–π stacking interactions [shortest centroid–centroid distance = 3.799 (8) Å and interplanar distance = 3.469 (2) Å] are observed.

Dimeric (2-cyano-phenolato-κO){2,2'-[ethyl-enebis(nitrilo-methyl-idyne)]diphenolato-κO,N,N',O'}manganese(III) monohydrate.

The molecules of the title compound, [Mn(C7H4NO)(C16H14N2O2)]·H2O, form dimers in the solid state across a crystallographic inversion center. The bridging Mn2O2 group is built of phenoxy groups, and is asymmetric, with an Mn—O distances of 1.9002 (13) and 2.6236 (14) Å. A substantial cavity between the two Mn atoms [Mn⋯Mn = 3.5082 (4) Å] is produced by the formation of the dimer. In the crystal, an extended network of O—H⋯O hydrogen-bonding interactions stabilizes the structure.