Synthesis, crystal structure, quantum chemical calculations, electrochemistry and electro-catalytical properties as cytochrome P-450 model of tetradentate Mn(III)-Schiff base complex.

The tetradentate Schiff base ligand has been obtained from condensation with mixing ethylenediamine and 2 mmoles of 5-methoxy-2-hydroxybenzaldehyde in absolute ethanol H2L. To the ethanolic solution was added manganese(II)acetatetetrahydrated and lithium chloride (LiCl) to obtain the tetradentate manganese(III) Schiff base complex [Mn(III)(Cl)L]. Theprepared compounds have been characterized by several spectroscopic techniques such as elemental analyses, FT-IR, UV–vis., 1H NMR and HRMS. In this paper, the X-ray diffraction (XRD) and the computational studies (DFT) of the ligand(H2L) with its manganese(III)-Schiff base complex [Mn(III)(Cl)L] are described and confirmed the given molecularstructures. The crystallographic studies have been utilized toelucidate the kinetics, selectivity and stereochemistry of thetransferred oxygen atomsto the substrate molecules when the considered complex is used as catalyst accordingthecytochrome P450 model. In addition, the density functional theory (DFT) calculation with B3LYP/6-31G(d,p) level isperformed to obtain the optimized geometries and electronic properties of the prepared compounds. The global reactivityparameters have also been calculated using the energies of frontier molecular orbitals suggesting that the ligand H2L is morestable than its Mn(III) complex. This may be due to the presence of hydrogen bonds in the ligand and the weaker energies ofcoordination bonds in the complex. The electrochemical behaviour of Mn(III)(Cl)L has been studied by cyclic voltammetryin acetonitrile solutions at room temperature. The resulting cyclic voltammogram shows Mn(III)/Mn(II) couple at E1/2= -0.62V with glassy carbon (GC) electrode. This redox couple is involved in the electrocatalytic cycle where themanganese(III) cation is successively mono-electronated until the formation of superoxo intermediates and then the oxospecies, respectively. These oxo forms, generated in situ, transfer their oxygen atoms to the substrate giving the oxidizedproduct. So, the chemical and electrochemical reactions, implicated in this electrocatalytical process, obey to the biomimeticoxidation reactions as those of monooxygenase enzymes (Cytochrome P450)

A novel copper(II)-Schiff base complex containing pyrrole ring: Synthesis, characterization and its modified electrodes applied in oxidation of aliphatic alcohols

International audienceA new copper(II) complex Cu(II)-L containing N2O2 donor atoms has been prepared from 6-[3′-(N-pyrrol)propoxy]-2-hydroxyacetophenone and diaminoethane in the presence of copper acetate monohydrate. It was characterized by spectroscopic methods such as FT-IR, UV-vis, mass spectra, elemental analysis and cyclic voltammetry. The molecular structure of Cu(II)-L has also been confirmed by X-ray diffraction analysis. The electrochemical behavior of copper(II)-Schiff base complex containing pyrrol groups has been investigated in DMF and acetonitrile solutions using cyclic voltammetry. Thus, conducting polymeric films of polypyrrole were obtained on the surfaces of glassy carbon and ITO electrodes using copper(II) complex as monomer. The modified electrodes were electrochemically and morphologically characterized and their electrocatalytic properties in heterogeneous phase have also been investigated. The AFM studies show that the morphology of polypyrrole (PPy) films on ITO-electrodes depends on the number of cyclical scans. The electrocatalytic performances of this complex seem to be more efficient towards the electro-oxidation of isopropylic alcohol than any other kinds of alcohols such as methanol, ethanol and benzyl alcohol. The electro-reduction of carbon dioxide was also examined

Bentonite Modified Carbon Paste Electrode as a Selective Electrochemical Sensor for the Detection of Cadmium and Lead in Aqueous Solution

This work describes the use of a carbon paste electrode (CPE) modified with a Bentonite clay (Maghnite) as an electrochemical non-pollutant, selective and low cost sensor for Cadmium and Lead detection in aqueous solution. The physico-chemical properties of the clay mineral were analysed by X-Ray Fluorescence analysis (XRF), Powder X-ray diffraction (XRD), Thermogravimetric analysis (TG) and N2 adsorption isotherm. The square wave anodic stripping voltammetry (SWASV) has been used in which the different electrochemical parameters have been studied. The optimal preconcentration pH and Maghnite-CPE content were found to be 3.4 and 14% w/w respectively. Under these optimized conditions and at a preconcentration time of 5 min, the response of the electrode was linear with analytes concentration in the ranges from 1 to 30 μmol/L for Cadmium and 0.1 to 30 μmol/L for Lead with limit of detection (LOD) values of 0.16 μmol/L and 0.30 μmol/L for Cadmium and Lead respectively.We acknowledge the MESRS and DG–RSDT (Ministère de l’Enseignement Supérieur et de la Recherche Scientifique et la Direction Générale de la Recherche - Algérie) for financial support. Financial support from the Spanish Ministerio de Economía y Competitividad and FEDER funds (MAT2016-76595-R) is also gratefully acknowledged

A selective naked-eye chemosensor derived from 2-methoxybenzylamine and 2,3-dihydroxybenzaldehyde - synthesis, spectral characterization and electrochemistry of its bis-bidentates Schiff bases metal complexes

A new colorimetric receptor HL, acting as a bidentate Schiff base ligand, has been synthesized by condensation of 2-methoxybenzylamine on 2,3-dihydroxybenzaldehyde in a methanolic solution. Interestingly, this chelating agent can selectively detect Cu2 +, Co2 +, Fe2 + and Fe3 + ions with a simple and an easy-to-make, well defined naked-eye visible color changes in two different solvents like acetonitrile and methanol. This bidentate ligand coordinates three metal ions of Co(II), Cu(II) and Fe(II) via nitrogen and oxygen atoms. The molecular structures of the synthesized compounds were elucidated by various physicochemical properties such as the elemental analysis, FT-IR, HNMR, UV–Vis and the Mass spectrometry. The resulting general formulae [M(L)2·H2O] (M(II) = Cu, Fe, Co) are proposed as mononuclear complexes. The solvatochromism properties of these compounds were studied with their absorption spectra using different solvents as methanol (MeOH), acetonitrile (AN), tetrahydrofuran (THF), dimethylformamid (DMF), dimethylsulfoxid (DMSO) and dichloromethane (DC). The Electrochemical behavior of copper complex was explored in DMF solutions by cyclic voltammetry (CV) with two working electrodes: glassy carbon (GC) and platinum electrode (Pt). This study reveals that copper complex shows successively two redox systems as CuIII/II and CuII/I. The FeIII/II and CoII/I redox systems have also been studied in DMF and DMSO media.The authors would like to thank the Algerian Ministère de l'Enseignement Supérieur et de la Recherche Scientifique et la Direction générale de la Recherche and the Ministerio de Economía y Competitividad for their undeniable financial support (MAT2016-76595-R). RRR thanks The Spanish Ministry of Economy and Competitiveness (MINECO) for a “Juan de la Cierva” contract (JCI-2012-12664)

Electrocatalytical reduction of bromocyclopentane and iodobenzene using Cobalt(III) and Nickel(II) Tris- and Bis-bidentates Schiff Bases Complexes

The following bidentate Schiff base: 2-[(4-Methoxybenzyl)iminomethyl]-phenol (HL), was employed as an asymmetric ligand in the synthesis of two mononuclear nickel(II) and cobalt(III) complexes (Ni(II)-2L and Co(III)-3L). This ligand has been synthesized via condensation of salicylaldehyde and 4-methoxybenzylamine in methanolic solution, while the both complexes result from complexation of metal(II) chloride hydrate salts with HL. These coordination compounds were structurally characterized by elemental analysis, FT-IR, UV-Vis, 1H NMR and 13C NMR spectral studies. Moreover, the electrochemical properties of both complexes were studied by cyclic voltammetry in DMF solution containing 0.1 M tetra-n-butylammonium tetrafluoroborate (Et4NBF4). This study reveals that each complex showed successively two redox couples: M(III)/M(II) and M(II)/M(I). Finally, the electrocatalytic activity of these complexes has been examined and it has been found that the both complexes worked as effective homogeneous electrocatalysts for the electroreduction of bromocyclopentane and iodobenzene using glassy carbon as working electrode.The authors would like to thank the MESRS and DG–RSDT (Ministère de l’Enseignement Supérieur et de la Recherche Scientifique et la Direction Générale de la Recherche - Algérie) for financial support. This work is supported by the Ministerio de Economia y Competitividad (MAT2016-76595-R)

A novel ferrocenic copper(II) complex Salen-like, derived from 5-chloromethyl-2-hydroxyacetophenone and N-ferrocenmethylaniline: Design, spectral approach and solvent effect towards electrochemical behavior of Fc+/Fc redox couple

This paper reports the synthesis, spectroscopic characterizations and electrochemical behavior of the obtained tetradentate copper (II)-Schiff base complex with its two wings as ferrocenylaniline moieties. This new ferrocenic derivative with two ferrocenylaniline entities surrounding the copper (II)-Salen complex (5) was synthesized by reacting N-ferrocenmethyl-N-phenyl-5-aminomethyl-2-hydroxyacetophenone (3) with one half equivalent of 1,2-diaminoethane in absolute ethanol. As for the intermediates involved in this synthetic sequence, the compound (3) was prepared in tetrahydrofuran (THF) by reacting N-ferrocenmethylaniline (2) with 5-chloromethyl-2-hydroxyacetophenone (1) in presence of sodium hydrogenocarbonate (NaHCO3). The compound (3) condensed on the diamine yields the Schiff base ligand (4). Under a nitrogen atmosphere and stirring at 50 °C, the ligand dissolved in absolute ethanol with stoichiometric amount of copper acetate monohydrate (Cu(COOCH3)2·H2O) formed the expected tetradentate Cu(II)-Schiff base complex (5) after 6 h of reaction. All these synthesized compounds gave yields varying from 50 to 90%. Their purities were estimated from elemental analysis while the molecular structures were elucidated with FT-IR, UV–Vis, 1H- and 13C- NMR. For the obtained copper complex, it is tetracoordinated in a distorted square planar environment with two nitrogen and two oxygen atoms as donor sites. The electrochemical behaviors of the synthesized compounds were explored using cyclic voltammetry. This investigation showed an important anodic shifting of the Epc and Epa potential waves for the Fc+/Fc redox couple of compound (3) in dichloromethane (DC) medium, compared to other polar media like acetonitrile (AN), dimethylformamide (DMF) and dimethylsulfoxide (DMSO). This behavior was also observed for the tetradentate copper (II)-Salen complex with its different metallic centers.The authors would like to thank the MESRS and DG-RSDT (Ministère de l’Enseignement Supérieur et de la Recherche Scientifique et la Direction Générale de la Recherche et du Développement Technologique- Algérie) for their financial support. Financial support from the Ministerio de Economía y Competitividad (Spain) and FEDER funds (MAT2016-76595-R) is also gratefully acknowledged

catena-Poly[[[(pyridine-κN)copper(II)]-μ-3-{1-[(2-amino­eth­yl)imino]­eth­yl}-6-methyl-2-oxo-2H-pyran-4-olato-κ4 N,N,O 4:O 2] perchlorate]

In the title compound, {[Cu(C10H13N2O3)(C5H5N)]ClO4}n, the CuII atom has an N3O2 coordination sphere. The complex contains two different ligands, viz. a pyridine mol­ecule and a Schiff base mol­ecule, resulting from the condensation of ethyl­enodiamine with dehydro­acetic acid. The CuII atom exhibits a square-pyramidal geometry: three of the four donors of the pyramid base belong to the Schiff base ligand (an N atom from the amine group, a second N atom from the imine group and the O atom of the pyran­one residue) and the fourth donor is the pyridine N atom. The coordination around the metal ion is completed by a longer axial bond to the pyran­one O atom of an adjacent Schiff base, so forming a one-dimensional polymer. The complex has a +1 charge that is compensated by a perchlorate ion. The crystal packing, which can be described as alternating chains of cations and tetra­hedral perchlorate anions along the a axis, is stabilized by inter­molecular N—H⋯O, C—H⋯O and C—H⋯N hydrogen-bonding interactions

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]

Poly(pyrrole) films efficiently electrodeposited using new monomers derived from 3-bromopropyl-N-pyrrol and dihydroxyacetophenone—Electrocatalytic reduction ability towards bromocyclopentane

International audienceElaboration of new modified electrodes electrodeposited on GC and ITO-electrodes.•Poly(pyrrole) films, analyzed by FT-IR, confirm the presence of functional groups.•ITO–Poly(pyrrole) films were explored by SEM, EDX and AFM spectroscopy.•Interesting catalytic properties have been also investigated