Composite Films of Metal Hexacyanoferrate and Poly (1,8-diaminonaphthaline) Derivatives: Electrosynthesis and Properties

The details of a potentiodynamic preparation method for a composite nickel(II) and copper(II) hexacyanoferrate (MeHcF) and poly[8-(3-acetylimino-6-methyl-2,4-dioxopyran)-1-aminonaphthaline] (PAMDAN) on a platinum electrode, (Pt |PAMDAN|MeHcF) are reported. The cyclic voltamograms recorded the direct deposition and growth of inner layer (PAMDAN) and the outer layer (MeHcF) from their solutions. The two composite electrodes show an improvement in the redox response. The voltammetric characteristics of the composite modified electrodes were also investigated in presence of different alkali metal cations (Li+, Na+, K+ and NH4+). The heterogeneous electron transfer processes involving the composite and their stability were examined by subjecting the system to the long term cyclic voltammetric potential cycling in 0.2 M NaCl electrolyte also after exposing the modified electrode to air for about 48 h then cycled in 0.2 M NaCl solution. Bilayer composite electrodes exhibit higher ionic conductivity, higher stability in comparison with pure inorganic (MeHcF) films. The inner electroactive polymer chains in the film cause enhancement in the electric conductivity of the composite electrodes

Electropolymerization of diaminofluorene and its electrochemical properties

AbstractPoly 2,7-diaminofluorene (PDAF)/Au modified electrode was prepared using 2,7-diamino fluorene (DAF) dissolved in acetonitrile (ACN) containing 0.1M LiClO4 using consecutive multisweep cyclic voltammetry (CV) and controlled potential electrolysis (CPE) techniques. Factors affecting the film formation, such as limits of potential cycling, sweep rate, number of sweeping cycles, monomer concentration, and also polymerization techniques were examined in detail. It was found that the optimum conditions, using a potentiodynamic technique on Au electrode as the working electrode, are by sweeping the potential between –200mV and 800mV at a sweep rate of 50mV/s for 10 cycles using 5mM DAF monomer solution. The obtained modified electrode was active only in acidic aqueous solutions (pH range from 0 to 2) and its activity was found to be pH dependent. PDAF was isolated and characterized using UV–vis, 1HNMR and SEM analyses. The electrical conductivity was found to be 1.5×10−5Scm−1. An electropolymerization mechanism was proposed and discussed based on the obtained experimental data and molecular orbital calculations. The obtained modified electrode has been found to improve the electrochemical reversibility and decrease the overpotential of hydroquinone. PDAF/Au was stable chemically and electrochemically both in aqueous and organic solutions, making it an excellent candidate for sensing and/ or electrocatalytic applications

Magnetic properties of the honeycomb oxide Na2_2Co2_2TeO6_6

We have studied the magnetic properties of Na$_2$Co$_2$TeO$_6$, which features a honeycomb lattice of magnetic Co$^{2+}$ ions, through macroscopic characterization and neutron diffraction on a powder sample. We have shown that this material orders in a zig-zag antiferromagnetic structure. In addition to allowing a linear magnetoelectric coupling, this magnetic arrangement displays very peculiar spatial magnetic correlations, larger in the honeycomb planes than between the planes, which do not evolve with the temperature. We have investigated this behavior by Monte Carlo calculations using the $J_1$-$J_2$-$J_3$ model on a honeycomb lattice with a small interplane interaction. Our model reproduces the experimental neutron structure factor, although its absence of temperature evolution must be due to additional ingredients, such as chemical disorder or quantum fluctuations enhanced by the proximity to a phase boundary.Comment: 9 pages, 13 figure

Kitaev interactions in the Co honeycomb antiferromagnets Na3Co2SbO6 and Na2Co2TeO6

Co$^{2+}$ ions in an octahedral crystal field, stabilise a j$_{eff}$ = 1/2 ground state with an orbital degree of freedom and have been recently put forward for realising Kitaev interactions, a prediction we have tested by investigating spin dynamics in two cobalt honeycomb lattice compounds, Na$_2$Co$_2$TeO$_6$ and Na$_3$Co$_2$SbO$_6$, using inelastic neutron scattering. We used linear spin wave theory to show that the magnetic spectra can be reproduced with a spin Hamiltonian including a dominant Kitaev nearest-neighbour interaction, weaker Heisenberg interactions up to the third neighbour and bond-dependent off-diagonal exchange interactions. Beyond the Kitaev interaction that alone would induce a quantum spin liquid state, the presence of these additional couplings is responsible for the zigzag-type long-range magnetic ordering observed at low temperature in both compounds. These results provide evidence for the realization of Kitaev-type coupling in cobalt-based materials, despite hosting a weaker spin-orbit coupling than their 4d and 5d counterparts

Composite Films of Metal Hexacyanoferrate and Poly (1,8-diaminonaphthaline) Derivatives: Electrosynthesis and Properties

The details of a potentiodynamic preparation method for a composite nickel(II) and copper(II) hexacyanoferrate (MeHcF) and poly[8-(3-acetylimino-6-methyl-2,4-dioxopyran)-1-aminonaphthaline] (PAMDAN) on a platinum electrode, (Pt |PAMDAN|MeHcF) are reported. The cyclic voltamograms recorded the direct deposition and growth of inner layer (PAMDAN) and the outer layer (MeHcF) from their solutions. The two composite electrodes show an improvement in the redox response. The voltammetric characteristics of the composite modified electrodes were also investigated in presence of different alkali metal cations (Li+, Na+, K+ and NH4+). The heterogeneous electron transfer processes involving the composite and their stability were examined by subjecting the system to the long term cyclic voltammetric potential cycling in 0.2 M NaCl electrolyte also after exposing the modified electrode to air for about 48 h then cycled in 0.2 M NaCl solution. Bilayer composite electrodes exhibit higher ionic conductivity, higher stability in comparison with pure inorganic (MeHcF) films. The inner electroactive polymer chains in the film cause enhancement in the electric conductivity of the composite electrodes

Tautomerism of Some 5-Arylazo-2-thiohydantoin Derivatives as a Criterion of Their Acidity

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Electrochemical behaviour of some 1,3,4-thiadiazole derivatives: Part 2 - Effect of acid and base on electro-oxidation mechanism of 2-benzoylamino- 5-( 1-cyanoarylhydrazono )-1,3,4-thiadiazoles at a platinum anode

864-867The oxidation of the title compounds in acetonitrile containing LiClO4 as supporting electrolyte, in both acidic and basic media, has been studied by cyclic voltammetry, coulometry and preparative electrolysis. In the presence of HClO4, the compounds are oxidized in the protonated forms and the main products are the corresponding perchlorate salts, whereas in media containing γ-collidine, the anion is the oxidizable moiety and the 4-aminocinnoline derivative is the main product. Mechanism of electrochemical oxidation is proposed and discussed

Anodic polymerization of 1-amino-2-methyl-9,10-anthraquinone in mixed solvent

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