A new ternary ruthenium(III) complex with 1,3-bis(salicylideneamino) propan-2-ol and 3-picolylamine: Synthesis, characterization, density functional theory and preparation of electrochemical sensor for nitrite analysis.

International audienceA novel electrochem. sensor based on graphite (G) functionalised with a new ternary ruthenium(III) complex was developed and applied to detect nitrite in aq. soln. The Ru(III) complex was synthesized using 1,3-bis(salicylideneamino) propan-2-ol polydentate Schiff base (BSAP) and 3-Picolylamine (PLA), and was characterized by elemental anal., Fourier transform IR spectroscopy (FT-IR), UV-visible spectrophotometry (UV-Visible), gradient-assisted hetero nuclear single quantum coherence spectroscopy (gHSQC) and cyclic voltammetry technique. In addn., the structure of the synthesized complex was optimized using d. functional theory (DFT). The results showed that the ternary Ru(III)-BSAP-PLA complex was formed and the adapted structure was an tetrahedral geometry.The electrochem. behavior of nitrite at the sensor prepd. using G/Ru(III)-BSAP-PLA composite shows that the evaluated electron transfer coeff. (α = 0.83) indicates a very significant electrocatalytic mechanism for oxidn. of nitrite in the presence of the Ru(III)-BSAP-PLA complex.Comparing to other published works, the sensor developed using G/Ru(III)-BSAP-PLA exhibited low limit of detection (LOD = 1.81 μM) around pH = 7. [on SciFinder(R)

Spectrometric Analyses, Structure and Voltammetric Study of Nickel(II) with N[(1E) Phenylmethylene N2[2(2Hydroxyphenylmethylene]Amino ethyl) Imidazolidin-1-yl Ethylamine

The reaction of N[(1E) phenylmethylene N2[2(2hydroxyphenylmethylene]amino ethyl) imidazolidin -1-yl ethylamine ligand (H 3 L) with nickel(II) salt, by heating at 40°C and addition of NaOH in excess, was made by eliminating of the phenol substituted imidazolidine ring, giving the mononuclear nickel(II) complex of the deprotonated bis-salicylaldehyde-triethylenetetramine (L −2 ). UV-Vis, FTIR and structural resolution show an octahedral geometry for [NiL]·6H 2 O complex. This compound has been characterized by single crystal X-ray diffraction study. This technique reveals that Ni-H 2 L involves a high-spin nickel(II) ion within a pseudo-octahedral geometry. The Ni(II) complex has NiN 4 O 2 coordination sphere as established from a crystal structure determination. The crystals of Ni(II) complex are tetragonal, space group P4/ncc, a = b = 19.348 A; c = 13.201 A. R(F) value (0.0528) found shows a very good precision of the determined geometrical parameters. Cyclic voltammetry of nickel complex is indicative of electronic communication between the nickel center via Schiff base ligand. The results obtained confirm the imidazolidine ring-cleavage reaction and the elimination of the substituted phenol on this ring and show that the presence of H 3 L ligand around the metallic center stabilizes the oxidation of the Ni(II) to Ni(III)

Evaluation of adsorption capacities of humic acids extracted from Algerian soil on polyaniline for application to remove pollutants such as Cd(II), Zn(II) and Ni(II) and characterization with cavity microelectrode.

International audienceThe adsorption capacities of new humic acids isolated from Yakouren forest (YHA) and Sahara (Tamenrasset: THA) soils (Algeria) and commercial humic acid (PFHA) on polyaniline emeraldine base (PEB) were studied at pH 6.6. Also the adsorption of heavy metals such as Cd2+, Zn2+ and Ni2+ on humic acid-polyaniline systems (HA-PEB) was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy (SEM), infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd2+, Zn2+ and Ni2+ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities (q(max)) of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that q(max) of Cd2+, Zn2+ and Ni2+ on HA-PEB followed the order: THA-PEB > YHA-PEB > PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB

Electrochemical sensors using modified electrodes based on copper complexes formed with Algerian humic acid modified with ethylenediamine or triethylenetetramine for determination of nitrite in water.

International audienceThe response and efficiency of new sensors for nitrite ions analysis have been studied electrochemically. These sensors were developed by modifying a carbon paste electrode (CPE) with copper (II) complexes formed with commercial (PFHA) and Algerian (YHA) humic acids and their modified compounds with ethylenediamine (EDA) or triethylenetetramine (TETA). The developed mechanism is based on the electrochemical oxidation of NO2(-) on the modified CPE for different nitrite concentrations. The obtained results showed that the carbon paste electrode modified with copper (II)-modified humic acids complexes (Cu-MHA) exhibited substantial electrocatalytic effect on the oxidation of nitrite anions compared with carbon paste electrode. The sensitivity of the modified CPE towards nitrite concentrations depends on the nature of the humic acid and its modified compounds. The measurements performed by using CPE/Cu-YHA-EDA and CPE/Cu-YHA-TETA gave the best sensitivity and a good linear response of current versus nitrite concentrations. The oxidation peak current of nitrite at CPE/Cu-YHA-TETA and CPE/Cu-YHA-EDA electrodes in weak acid solution is proportional to the concentration of nitrite over the range 0-1.38×10(-2)molL(-1) with a limit of detection (LOD) of 1.46μmolL(-1) (Sensitivity=41.06μA(mmolL(-1))(-1) and 2.17μmolL(-1) (Sensitivity=27.63μA(mmolL(-1))(-1), respectively. Compared to the sensors published in the literature, our CPE/Cu-YHA-TETA and CPE/Cu-YHA-EDA electrodes exhibit a good catalytic activity towards nitrite oxidation and a low limit of detection over a wide nitrite concentrations range

Effectiveness study of sensor based on modified cavity microelectrode by Algerian humic acid-polyaniline composites using square wave voltammetry

International audienceThe response and efficiency of a new sensor based on cavity microelectrode (CME) modified with Algerian humic acid-polyaniline emeraldine base composites (HA-PEB) towards concentration of nickel and cadmium has been studied by square wave voltammetry technique (SWV). The developed mechanism is based on the electrochemical reduction of metal to CME modified with HA-PEB for different metal concentrations. The electrochemical study was performed in H2SO4 (0.5 mol/L) at room temperature in the potential range between −0.15 and −0.5 V towards saturated calomel electrode (SCE). The obtained results show that the CME modified with HA-PEB composites responds sensitively to variation of Ni2+ and Cd2+ concentrations, whatever the nature of humic acid. The measurements performed using CME modified with Yakouren humic acid (YHA)-PEB and Tamanrasset humic acid (THA)-PEB gave better sensitivity and good linearity of current versus metal concentration. The application of the sensor to detect heavy metals in water of the Sebaou River (Kabylia, Algeria) revealed that the CME modified with PEB does not detect different metals, while the sensor based on CME-HA-PEB has the ability to detect the presence of more metals in river water. Finally, it can be concluded that HA extracted from Algerian soils play an important role in the effectiveness of the sensor based on cavity microelectrode

Supercapacitor electrode based on ternary activated carbon/CuCoO2 hybrid material

International audienceIn this work, a supercapacitor electrode was prepared using modified ternary activated carbon (AC ODS : Ternary Olive-Date-Sugar activated carbon) by CuCoO 2 bimetallic oxide. The hydrothermal synthesis of CuCoO 2 was successfully carried out, and then the doping on activated carbon was done. Subsequently, the characterization of the hybrid material by ATR, SEM, XRD, Zeta potential, XPS, Raman, TGA, and electrochemical methods were studied in a binary electrolyte (1 M H 2 SO 4 /KCl). The electrochemical results indicate that AC ODS /CuCoO 2 modified electrode exhibits excellent pseudo-capacitive behavior, with a specific capacitance of 1052.95 F g -1 at 0.3 A g -1 and high specific energy (161.23 Wh.kg - 1 ) at high current (8 A g -1 ). High specific capacitance of 103.12 F g -1 and a specific capacitance retention reaches up to 95.41 % after 10 4 charge-discharge cycles at 20 A g -1 were also obtained. This study revealed that the activated carbon modified with CuCoO 2 oxide offers a significant improvement in the specific capacitance and the specific energy with a high specific current. Based on these results, AC ODS /CuCoO 2 can be explored as supercapacitor electrode for energy storage, and that in terms of specific capacitance, this hybrid material gives the most important result ever obtained with this oxide

Crystal structure, chemical reactivity, kinetic and thermodynamic studies of new ligand derived from 4-hydroxycoumarin Interaction with SARS-CoV-2

International audienceCurrently, Covid-19 pandemic infects staggering number of people around the  and causes a high rate of mortality. In order to fight this disease, a new coumarin derivative ligand (4-[(-3-) ]-2-chromen-2-one) (L) has been synthesized and characterized by single-crystal X-ray diffraction, NMR, ATR, UV-Visible and cyclic voltammetry. Chemical reactivity, kinetic and thermodynamic studies were investigated using DFT method. The possible binding mode between L and Main protease (Mpro) of SARS-CoV-2 and their reactivity were studied using molecular docking simulation. Single crystal X-ray diffraction showed that L crystallizes in a monoclinic system with 2  space group. The reactivity descriptors such as nucleophilic index confirm that L is more nucleophile, inducing complexation with binding species like biomolecules. The kinetic and thermodynamic parameters showed that the mechanism of crystal formation is moderately exothermic. The binding energy of the SARS-CoV-2/Mpro-L complex and the calculated inhibition constant using docking simulation showed that the active L molecule has the ability to inhibit SARS-CoV-2

A new electrochemical sensor based on carbon paste electrode/Ru(III) complex for determination of nitrite: Electrochemical impedance and cyclic voltammetry measurements

International audienceThe modified carbon paste electrode with Ru(III) complex was studied as a novel sensor for the determination of nitrite. The behavior of NO2− at the electrode surface was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS provided useful information on the charge transfer resistance (R) at the electrode/solution. The EIS measurements showed that R is low at oxidation potentials, and decreases with increasing temperature. The increase of the constant phase element with temperature is due to the accumulation of nitrite on the electrode, thus, facilitating the electron transfer between electrode and NO2−. CV was used to study the effect of pH on the electro-catalytic oxidation of NO2− and to determine the limit of detection (LOD). CV measurements showed a good linear relationship between the oxidation current and the concentration of NO2− over a wide concentration range 0–1.38 × 10−2 mol L−1. Low detection limit of 1.39 × 10−6 mol L−1 toward NO2− was obtained. LOD decreased by 23.2% compared to that determined using cavity microelectrode. © 2016 Elsevier Lt

A novel hybrid carbon materials-modified electrochemical sensor used for detection of gallic acid

International audienceNovel hybrid carbon materials such as activated carbon-carbon nanotubes (AC-CNTs) and carbon spheres/activated carbon-carbon nanotubes (CSs/AC-CNTs) based on activated carbon (AC) derived from the pits of Algerian date palm have been prepared and characterized. In addition, the carbon paste electrodes based on graphite carbon (GC) and cavity microelectrode (CME) modified with these hybrid materials were used to detect gallic acid at pH = 7 using square wave voltammetry method (SWV). The conductivity measurements revealed that CSs/AC-CNTs is more conducting than AC-CNTs. SWV measurements showed that the oxidation current was directly proportional to the concentrations of gallic acid (from 0 to 0.00536 M) with the lowest limit of detection (LOD), reaching 6.43 µM and 3.64 µM using GC/CSs/AC-CNTs electrode and CME/GC/CSs/AC-CNTs sensor, respectively. The reproducibility and the stability of the studied sensor were confirmed by the relative standard deviation of the oxidation current response of gallic acid (RSD Reproducibility = 1.44% and RSD Stability = 3.7%)