scholarly journals ELECTROCHEMICAL INVESTIGATIONS OF THE INTERACTION OF CAFFEINIUM COMPOUNDS WITH POLYANІОNES OF Мо AND W WITH OF 1,3,5 - TRIPHENYL VERDAZYL RADICAL

2021 ◽  
Vol 86 (12) ◽  
pp. 124-133
Author(s):  
Olha Panteleieva ◽  
Kateryna Plyasovskaya ◽  
Olexandr Shtemenko
Keyword(s):  
Concentration Ratio ◽  
Chemical Nature ◽  
Spectrophotometric Analysis ◽  
Model Reaction ◽  
Electrochemical Studies ◽  
X Ray Diffraction ◽  
Active Centers ◽  
X Ray ◽  
Verdazyl Radical ◽  
Cathode Current

The work continues the study on the peculiarities of the interaction of 1,3,7-trimethylxanthine (caffeine) compounds with polyoxometalates of molybdenum and tungsten with the artificial radical of 1,3,5- triphenylverdazyl (TFV). Using the example of a model reaction with the TFV radical, these compounds showed a special antiradical action. Based on the research results, it was found that the nature of the destruction of the radical when interacting with (HСaf)3[PМ12O40]∙6H2O (where М = Мо, W) differs from most known systems, which are characterized by a mechanism of disproportionation. The data obtained confirmed the previously made assumption about the chemical nature of these interactions. To establish the stoichiometry of the reaction between TFV and (HСaf)3[PW12O40], electrochemical studies were conducted which showed that the activity of the radical is restored after exceeding the concentration ratio of 12 : 1, respectively. The synergism of the components of the compound (HСaf)3[PW12O40] is shown: when TFV interacts with H3[PW12O40], the maximum cathode current characteristic of TFV occurs at a concentration ratio of 4 : 1, respectively, while caffeine has no antiradical effect at all. Previously obtained data from X-ray diffraction analysis of compounds (HСaf)3[PMo12O40]∙6H2O, (HСaf)3[PW12O40]∙6H2O prove that the orientation of protonated caffeine relative to polyoxamethalate-anion is possible due to hydrogen bonds =O…H–N=. This process can result in the delocalization of the charge over the entire O-enriched surface, by all twelve groups [О–Ме–О]-, which are part of the POM, making the latter active centers capable of interacting with TFV. Therefore, the data presented correlate with the previously obtained results of spectrophotometric analysis and X-ray diffraction data and confirm the previously made conclusions.

scholarly journals Non-invasive Electrochemical Detection of Glucose using CuO-NiO/MXene Modified Electrode

2020 ◽  
Author(s):  
Alaa Mohamed Elsafi ◽  
Vinotha Krishnasamy ◽  
Karthik Kannan ◽  
John-John Cabibihan ◽  
Abdulaziz Khalid AlAli ◽  
...  
Keyword(s):  
Morphological Analysis ◽  
High Selectivity ◽  
Proton Conductor ◽  
Carbon Electrodes ◽  
Electrochemical Studies ◽  
X Ray Diffraction ◽  
Characterization Methods ◽  
Glassy Carbon Electrodes ◽  
X Ray ◽  
Non Invasive

High levels of glucose or acetone in breath confirms diabetes disease. One of the analytical devices that detect changes in breath is the electrochemical sensor having high selectivity, easy to use and being able to meet diabetic patient’s needs. In this study, sensors were made by fabricating metal oxide coated glassy carbon electrodes and using nafion as a proton conductor. Characterization methods such as X-ray diffraction, FTIR and morphological analysis have been performed for metal oxides to characterize their atomic arrangement and composition. In addition, electrochemical studies were done using Gamry instrument and curves plotted as current in amperes versus voltage to test the coated electrodes conductivity. High selectivity sensors provide promising applications in any field.

Two New Mn(II) and Co(II) Complexes with the Tridentate 2,4,6-Tris(2-pyridyl)-1,3,5-triazine Ligand

2005 ◽  
Vol 60 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Arpi Majumder ◽  
Chirantan Roy Choudhury ◽  
Samiran Mitra ◽  
Christoph Marschner
Keyword(s):  
Single Crystal ◽  
Tridentate Ligand ◽  
Electrochemical Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Analyses

Two new complexes of manganese(II) and cobalt(II), [Mn(tptz)(OCH3CO)(H2O)2]ClO4 (1) and [Co(tptz) (OSO3) (H2O)2](H2O)2 (2) {where tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine}, have been prepared and characterised by elemental analyses, spectroscopic, electrochemical studies and single crystal X-ray diffraction. Single crystal X-ray analysis reveals complexes of Mn(II) and Co(II), where tptz remains intact and behaves as a tridentate ligand and forms heptacoordinated Mn(II) and hexacoordinated Co(II) complexes for 1 and 2, respectively.

Supramolecular assemblies of phenolic metalloporphyrins: Structures and electrochemical studies

2019 ◽  
Vol 23 (01n02) ◽  
pp. 103-116 ◽  
Author(s):  
Gia Co Quan ◽  
Morgane Denis ◽  
Brian Abeykoon ◽  
Jean-Bernard Tommasino ◽  
Erwann Jeanneau ◽  
...  
Keyword(s):  
Supramolecular Assembly ◽  
Electrochemical Studies ◽  
Redox Behavior ◽  
Metallic Ions ◽  
X Ray Diffraction ◽  
Supramolecular Compounds ◽  
One Dimensional ◽  
X Ray ◽  
Axial Coordination ◽  
Supramolecular Architectures

The reactivity of two phenolic porphyrins bearing respectively catechol and gallol-derived meso substituents (5,10,15,20-tetrakis(3,4-dihydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin) with trivalent metallic ions (Fe, Mn, In) was studied. Six supramolecular compounds were obtained and structurally characterized by single crystal X-ray diffraction. In each compound, the supramolecular assembly was based on the axial coordination of a phenolate function to the metallic ion lying in the porphyrinic core. A great diversity of supramolecular architectures was accessible through such simple arrangements, and objects ranging from dimers to one-dimensional polymers were isolated. Some of these assemblies were further investigated in solution by mass spectrometry and by UV-vis absorption spectroscopy. For the iron-based materials, the redox behavior was studied in solution through cyclic voltammetry experiments in inert conditions and under air.

scholarly journals [FeII(L•)2][TCNQF4•−]2: A Redox-Active Double Radical Salt

2019 ◽  
Vol 72 (10) ◽  
pp. 769 ◽  
Author(s):  
Ian A. Gass ◽  
Jinzhen Lu ◽  
Ruchika Ojha ◽  
Mousa Asadi ◽  
David W. Lupton ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Radical Anion ◽  
Electrochemical Studies ◽  
X Ray Diffraction ◽  
Neutral Radical ◽  
X Ray ◽  
Redox Active ◽  
Diffusion Controlled ◽  
Radical Salt ◽  
Radical Ligand

The reaction of [FeII(L•)2][BF4]2 with LiTCNQF4 results in the formation of [FeII(L•)2][TCNQF4•−]2·2CH3CN (1) (L• is the neutral aminoxyl radical ligand 4,4-dimethyl-2,2-di(2-pyridyl)oxazolidine-N-oxide; TCNQF4 is 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane). Single-crystal X-ray diffraction; Raman, Fourier-transform infrared (FTIR) and ultraviolet–visible spectroscopies; and electrochemical studies are all consistent with the presence of a low-spin FeII ion, the neutral radical form (L•) of the ligand, and the radical anion TCNQF4•−. 1 is largely diamagnetic and the electrochemistry shows five well-resolved, diffusion-controlled, reversible one-electron processes.

Enhancement of plasticity in Zr-based bulk metallic glasses

2007 ◽  
Vol 22 (9) ◽  
pp. 2454-2459 ◽  
Author(s):  
X.D. Wang ◽  
L. Yang ◽  
J.Z. Jiang ◽  
K. Saksl ◽  
H. Franz ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Concentration Ratio ◽  
Bulk Metallic Glasses ◽  
Amorphous Structure ◽  
Catastrophic Failure ◽  
X Ray Diffraction ◽  
Present Evidence ◽  
X Ray ◽  
The Stability ◽  
A Minor

We present evidence that a minor adjustment in Zr/Ni concentration ratio can dramatically enhance the plasticity of monolithic Zr-based bulk metallic glasses (BMGs) from about 2.2% for Zr65Al8Ni10Cu17 BMG to 14% for Zr62Al8Ni13Cu17 BMG. No deformation-induced nanocrystallization appears in a 55% strained Zr62Al8Ni13Cu17 BMG without catastrophic failure while pre-existing nanocrystals in Zr65Al8Ni10Cu17 BMG result in its limited plasticity. Also note that the stability of Zr62Al8Ni13Cu17 BMG against crystallization upon deformation is somewhat higher than that of Zr65Al8Ni10Cu17 BMG. As determined by x-ray diffraction using synchrotron radiation, the enhanced plasticity of Zr62Al8Ni13Cu17 BMG seems to be related to the relative homogeneity of the amorphous structure.

Insights into the Chemical Nature and Formation Mechanisms of Discharge Products in Na–O2 Batteries by Means of Operando X-ray Diffraction

2016 ◽  
Vol 120 (16) ◽  
pp. 8472-8481 ◽  
Author(s):  
R. Pinedo ◽  
D. A. Weber ◽  
B. Bergner ◽  
D. Schröder ◽  
P. Adelhelm ◽  
...  
Keyword(s):  
Chemical Nature ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
X Ray

Preparation and properties of solid electrolyte CaxBi1.7−xW0.3O3.45−0.5x electrolyte material by sol–gel combution method

2019 ◽  
Vol 12 (05) ◽  
pp. 1951001
Author(s):  
Jie Yang ◽  
Changan Tian ◽  
Yu Wang ◽  
Junjie Meng ◽  
Dongdong Ji ◽  
...  
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Combustion Method ◽  
Solid Oxide ◽  
Electrochemical Studies ◽  
Oxide Fuel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Differential Thermogravimetric Analysis

CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) ([Formula: see text], 0.05, 0.10, 0.15, 0.20, 0.30) electrolyte material were synthesized by sol–gel self-combustion method. The samples were characterized by thermogravimetric-differential thermogravimetric analysis(TG-DSC), X-ray diffraction, scanning electron microscopy (SEM), porosity and electrochemical impedance spectroscopy (EIS). The results show the powders CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) with fluorite crystal structure can be obtained after the precursor was calcined at 760∘C. When sintered at 780∘C for 2[Formula: see text]h, the compact ceramic sintered with relative density higher than 97% can be obtained. The electrochemical studies showed that CaxBi[Formula: see text]W[Formula: see text]O[Formula: see text] (CBW) have high ionic conductivity after 780∘C sintering. The sample Ca[Formula: see text]Bi[Formula: see text]W[Formula: see text]O[Formula: see text] exhibits a conductivity of 0.07978 S[Formula: see text][Formula: see text][Formula: see text]cm[Formula: see text] at 750∘C, and the activation energy is 0.845[Formula: see text]eV, which is expected to be applied to the electrolyte materials for intermediate temperature solid oxide fuel cells (SOFC).

Surface Studies and Nature of Active Sites of Supported Heteropolyacids as Catalysts in Methanol Dehydration

1994 ◽  
Vol 59 (4) ◽  
pp. 820-832 ◽  
Author(s):  
Amin Anwar ◽  
Ali Abdel-Ghaffar ◽  
Sameh Aboul-Fotouh ◽  
Ebeid Fikry
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Pore Radius ◽  
Catalytic Properties ◽  
Flow System ◽  
Total Pore Volume ◽  
X Ray Diffraction ◽  
Active Centers ◽  
X Ray ◽  
The Mean

Different amounts of molybdo- and tungstophosphoric acids were supported on α-Al2O3 to get information about their surface and catalytic properties. The surface study revealed that surface area, total pore volume and the mean pore radius decreased as the acid content increased. X-Ray diffraction analysis showed that there is no interaction between the acid and α-Al2O3. Using a continuous flow system, methanol transformation was carried out under atmospheric pressure. Some experiments were made to determine the nature of active centers and reaction mechanism.

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