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-[N-(4-{4-[(2-Hy­droxy-5-meth­oxy­benzyl­idene)amino]­benz­yl}phen­yl)carboximido­yl]-4-meth­oxy­phenol

In the title Schiff base, C29H26N2O4, the complete molecule is generated by a crystallographic twofold axis and is V-shaped. The planes of the benzene rings of the central diphenyl­methane unit make a dihedral angle of 78.11 (4)° while adjacent benzene and 5-meth­oxy­salicyl­idene rings are twisted with respect to each other by a dihedral angle of 11.84 (8)°. The Schiff base is in the enol–imino form and an intra­molecular O—H⋯N hydrogen bond is observed

Is the electrocatalytic epoxidation of stilbene isomers using manganese (III) tetradentate Schiff bases complexes stereoselective?

Three manganese (III) complexes were obtained with H2Salen derivatives and used as catalysts in the epoxidation reactions of E- and Z-stilbene isomers. The preparative electrolyses were carried out at 25 °C in acetonitrile solution containing 0.1 M TBAP, 10−3 M complex, 10−2 M 2-methylimidazole and 0.1 M benzoic anhydride plus stilbene as substrate. Our results showed clearly that E-stilbene was totally converted to Z-stilbene oxide whereas Z-stilbene leads to a mixture in which the benzaldehyde was the major by-product. In our experimental conditions, the turnovers recorded for different experiments were located in the 3.7–6.6 range. Keywords: Electrocatalysis, Manganese complexes, Olefins epoxidation, Molecular oxygen, Biomimetic catalysi

A comparative study of the addition effect of activated carbon obtained from date stones on the biological filtration efficiency using sand dune bed.

International audienceUp to now, even with the tremendous social and technological progress, pollution problems still occupy the focus of many researchers all over the world, and hence this paper focused on the treatment of domestic wastewater. In this context, a bi-layer filtration system made of sand dune and activated carbons have been developed. This latter was obtained from the hydrolysis of local date stones. The total thickness of the filter media was 60 cm. The height of the resulting bed ranged from 0 to 24 cm, and was controlled by adding only activated carbons. The efficiency of the filtration system was evaluated by monitoring the time-courses of COD and BOD5 values, as well as their evolution over the height of the bed. The comparison of these results to those obtained with a bed of sand dune only showed a clear enhancement of the efficiency which lay between 80-95 (%) for COD and 78-94 (%) for BOD

Removal of tiemonium methylsulfate, from aqueous solutions using activated carbon prepared from date stones

International audienceThe retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R2 > 0.98. The adsorption capacity of AC–DS was found to be 42.2 mg g−1 at 10°C and 60.5 mg g−1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG0 and ΔH0 confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS0

Removal of tiemonium methylsulfate, from aqueous solutions using activated carbon prepared from date stones

International audienceThe retention of a pharmaceutical compound, tiemonium methylsulfate (TIM), from aqueous solutions by adsorption onto activated carbon prepared from date stones (AC–DS) was investigated. Physical and chemical characteristics of this material were also determined. Results showed that pH 8 was optimal for TIM adsorption. Among the kinetic models considered, the pseudo-second-order model was the most appropriate to describe experimental data. Regarding adsorption isotherms, it was shown that the Sips model accurately describe the sorption of TIM onto AC–DS with a correlation factor R2 > 0.98. The adsorption capacity of AC–DS was found to be 42.2 mg g−1 at 10°C and 60.5 mg g−1 at 25°C, confirming its efficiency for the removal of this compound from aqueous solutions. The values of ΔG0 and ΔH0 confirmed that the adsorption of TIM onto AC–DS was spontaneous and endothermic in nature and hence more effective at high temperatures. An irregular increase in the randomness was suggested at the AC–DS solution interface during the adsorption process for positive values of ΔS0

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

339-353The 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)