Tris(2-{[2-(4-meth­oxy­phen­yl)eth­yl]imino­meth­yl}phenolato-κ2 N,O 1)cobalt(III)

In the title compound, [Co(C16H16NO2)3], the CoIII atom is six-coordinated in an irregular octa­hedral geometry by three N,O-chelating 2-{[2-(4-meth­oxy­phen­yl)eth­yl]imino­meth­yl}phenolate groups. One of the three meth­oxy group is disordered over two sets of sites with an occupancy ratio of 0.768 (5):0.232 (5). The crystal packing can be described by alternating zigzag layers of organic ligands and CoN3O3 octa­hedra along the c axis. There are no classical hydrogen bonds in the structure, but C—H⋯π inter­actions occur

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

Dimeric (2-cyano­phenolato-κO){2,2′-[ethyl­enebis(nitrilo­methyl­idyne)]diphenolato-κ4 O,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

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

2,4-Dichloro-6-({2-[(3,5-dichloro-2-hy­droxy­benzyl­idene)amino]­eth­yl}imino­meth­yl)phenol

The title mol­ecule, C16H12Cl4N2O2, lies about an inversion center. The symmetry-unique part of the mol­ecule contains an intra­molecular O—H⋯N hydrogen bond. In the crystal, mol­ecules are arranged in corrugated layers parallel to (-101). Weak π–π stacking inter­actions, with a centroid–centroid diatance of 3.7923 (13) Å, are present

2-[1-({2-[1-(2-Hy­droxy-5-{[meth­yl(phen­yl)amino]­meth­yl}phen­yl)ethyl­idene­amino]­eth­yl}imino)­eth­yl]-4-{[meth­yl(phen­yl)amino]­meth­yl}phenol

Mol­ecules of the title compound, C34H38N4O2, lie across crystallographic inversion centres. The crystal packing can be described by alternating zigzag chains along the c axis in which the molecules are linked by van der Waals interactions. There is an intra­molecular O—H⋯N hydrogen bond and the two benzene rings in the asymmetric unit make a dihedral angle of 79.81 (6)°

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

Nucleophilic displacement versus electron transfer in the reactions of alkyl chlorosilanes with electrogenerated aromatic anion radicals

International audienceAnion radicals of a series of aromatic compounds (C6H5CN, C6H5COOEt, anthracene, 9,10-dimethyl-, 9,10-diphenyl- and 9-phenylanthracene, pyrene and naphthalene) react with trialkyl chlorosilanes R1R2R3SiCl (R1-3 = Me, Et; R1,2 = Me, R3 = t-Bu) in multiple ways, following classical bimolecular schemes. The ratio of one-electron transfer (ET) to a two-electron process (SN2-like nucleophilic attack of the reduced form of mediator on the chlorosilane, with k2 ≅ 102-108 M−1 s−1) is inversely related to the steric availability of Si for nucleophilic displacement reactions. The nucleophilic substitution pathway mainly results in mono- and disilylated aromatic products. Paralleling the electrochemical data with DFT calculations, the role of silicophilic solvent (DMF) in SN process was shown to be quite complex because of its involvement into coordination extension at silicon, dynamically modifying energetics of the process along the reaction coordinate. Although 2,2'-bipyridine also forms delocalized persistent anion radicals, they do not induce neither ET nor SN reactions in the same manner as aromatic mediators. Silicophilicity of 2,2'-bipyridine being superior to that of DMF, a R3SiCl·bipy complex of hypercoordinated silicon with electroactive ligand was formed instead, whose reduction requires about 1 V less negative potentials than bipyridine itself

Оцінка якості розв'язку обернених задач геофізики на основі застосування статистичного критерію хі-квадрат

Повышение эффективности поисково-разведочных работ на нефть и газ возможно на пути развития интерпретационных систем, основанных на решении обратных задач геофизики. Наличие случайных погрешностей в измеряемых геофизических полях, а также существенная некорректность решения обратных задач геофизики делают актуальной проблему независимой оценки качества решения получаемого в результате реализации итерационного подбора. Предложено контролировать качество решения обратной задачи на основе использования критерия хи-квадрат оценки гипотезы о нормальности закона распределения остаточной невязки между наблюденным и рассчитанным геофизическими полями. Эффективность использования статистического критерия хи-квадрат для оценки качества решения обратной задачи гравиметрии проиллюстрирована практическим примеромEnhancement of the efficiency of oil and gas exploration work is possible while heading toward the development of interpretation systems, which are based on the geophysical inverse problems solutions. Presence of the random uncertainties in measured geophysical fields, as well as considerable ill-posed of the solutions of inverse problems of geophysical data make it an actual problem of independent estimation of the quality of the solution which is obtained as an outcome of realization of the iterative process. It is proposed to control the quality of the solution of the inverse problem on basis of the XI-square criterion use for assessment of the hypothesis of normalcy of distribution law of the residual discrepancy between observed and calculated geophysical fields. In the practical view the efficiency of the use of statistical estimation of the quality of the solution of the inverse problem of gravimetry was shown

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