scholarly journals Electrolytic Reduction of Titanium Dioxide in Molten LiCl–Li2O

Electrochem ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 224-235
Author(s):  
Meng Shi ◽  
Bin Liu ◽  
Shelly Li ◽  
Haiyan Zhao
Keyword(s):  
Detrimental Effect ◽  
Reduction Potential ◽  
Electrolytic Reduction ◽  
Cathodic Reduction ◽  
Solid Particles ◽  
Electrochemical Characteristics ◽  
Partial Reduction ◽  
Reduction Potentials ◽  
Dft Modeling ◽  
Optimal Reduction

The electrolytic reduction of TiO2 in LiCl–Li2O (1 wt.%) at 650 °C was investigated under a series of cathodic reduction potentials and applied charges to provide a mechanistic understanding of the electrochemical characteristics of the system. The optimal cathodic reduction potential was determined as being −0.3 V vs. Li/Li+. Li2TiO3 and LiTiO2 were structurally identified as intermediate and partial reduction products of the TiO2 electrolytic reduction. The reduction of LiTiO2 was extremely slow and reversible due to its high stability and the detrimental effect of Li2O accumulation within the solid particles. The most reduced product obtained in this study was LiTiO2, which was achieved when using 150% of the theoretical charge under the optimal reduction potential. The highest reduction extent obtained in this study was 25%. Based on theoretical DFT modeling, a detailed multistep reduction mechanism and scheme were proposed for TiO2 electrolytic reduction in LiCl–Li2O (1 wt.%) at 650 °C.

scholarly journals Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions

2021 ◽  
Vol 22 (2) ◽  
pp. 633
Author(s):  
Konrad Skotnicki ◽  
Slawomir Ostrowski ◽  
Jan Cz. Dobrowolski ◽  
Julio R. De la Fuente ◽  
Alvaro Cañete ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Density Functional ◽  
Reduction Potential ◽  
Biological Significance ◽  
Radical Cations ◽  
Basis Sets ◽  
Double Bonds ◽  
Reduction Potentials

The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●−, CO3●−) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●− with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning’s aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.

scholarly journals A Three-Step Approach to Estimation of Reduction Potentials of Natural Mixtures of Antioxidants Based on DPPH Test; Illustration for Catechins and Cocoa

Proceedings ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 4 ◽  
Author(s):  
Barbara Kusznierewicz ◽  
Monika Baranowska ◽  
Klaudia Suliborska ◽  
Wojciech Chrzanowski ◽  
Agnieszka Bartoszek
Keyword(s):  
Electrochemical Properties ◽  
Plant Extracts ◽  
Reduction Potential ◽  
Correlation Equation ◽  
Complex Mixtures ◽  
Test Results ◽  
Reduction Potentials ◽  
Dpph Test

The aim of this study is to propose a methodology to assess electrochemical properties of complex mixtures of antioxidants, such as plant extracts, based on the results of simple and popular DPPH test. The first, most difficult step, involves determinations of standard reduction potentials (E0) for the series of purified compounds (here catechins). The next step is the calculation of stoichiometric values (n10) based on the results of DPPH test for the same compounds. Finally, a correlation equation is formulated, which is then employed to estimate “cumulative reduction potential” (Ec) for the mixture of interest (here cocoa) using DPPH test results.

scholarly journals One-Electron Reduction Potentials: Calibration of Theoretical Protocols for Morita–Baylis–Hillman Nitroaromatic Compounds in Aprotic Media

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2129 ◽  
Author(s):  
Amauri Francisco da Silva ◽  
Antonio João da Silva Filho ◽  
Mário Vasconcellos ◽  
Otávio Luís de Santana
Keyword(s):  
Cyclic Voltammetry ◽  
Biological Activity ◽  
Chemical Structure ◽  
Reduction Potential ◽  
Chemical Reactivity ◽  
Nitroaromatic Compounds ◽  
Reduction Potentials ◽  
Electron Reduction ◽  
The One ◽  
Antileishmanial Activities

Nitroaromatic compounds—adducts of Morita–Baylis–Hillman (MBHA) reaction—have been applied in the treatment of malaria, leishmaniasis, and Chagas disease. The biological activity of these compounds is directly related to chemical reactivity in the environment, chemical structure of the compound, and reduction of the nitro group. Because of the last aspect, electrochemical methods are used to simulate the pharmacological activity of nitroaromatic compounds. In particular, previous studies have shown a correlation between the one-electron reduction potentials in aprotic medium (estimated by cyclic voltammetry) and antileishmanial activities (measured by the IC50) for a series of twelve MBHA. In the present work, two different computational protocols were calibrated to simulate the reduction potentials for this series of molecules with the aim of supporting the molecular modeling of new pharmacological compounds from the prediction of their reduction potentials. The results showed that it was possible to predict the experimental reduction potential for the calibration set with mean absolute errors of less than 25 mV (about 0.6 kcal·mol−1).

Electron and Proton Transfers around the b/f Complex in Chloroplasts: Modelling the Constraints on Q-cycle Activity

1988 ◽  
Vol 15 (4) ◽  
pp. 567 ◽  
Author(s):  
AB Hope ◽  
DB Matthews
Keyword(s):  
Reduction Potential ◽  
Slow Phase ◽  
Single Turnover ◽  
Reduction Potentials ◽  
Q Cycle ◽  
Proton Transfers ◽  
Proton Uptake ◽  
Time Standard ◽  
Electron Transfers ◽  
Stimulation Of

The requirements for the operation of a Q-cycle in thylakoids are discussed. A computer model is described in which the state of reduction of components of the b/f complex is followed, single turnover at a time. Standard reduction potentials from the literature were assigned to the cytochrome b563 molecules; those for the second electron oxidation of plastoquinol at p-sites, and for the reduction of plastoquone at n-sites, were found by optimising the predicted stimulation of proton uptake by valinomycin. The stimulation has been attributed to uptake by doubly reduced plastoquinone at b/f complexes, a process thought to continue only if the membrane potential (ΔV) is kept low by ionophores. ΔV was simulated in the model via the electrochromic signal; its effect on electron transfers in the b/f complex was incorporated by modifying the reduction potentials. The extent of valinomycin stimulation of proton uptake, its dependence on [valinomycin] and flash frequency, the slow phase of the electrochromic signal and the extent of cytochrome b reduction were predicted by the model when the standard reduction potential for the p-site was set at -0.05 to -0.08 V. with that for the n-site at about 0 V.

scholarly journals N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

2019 ◽  
Vol 15 ◽  
pp. 52-59 ◽  
Author(s):  
Fabienne Speck ◽  
David Rombach ◽  
Hans-Achim Wagenknecht
Keyword(s):  
Excited State ◽  
Nucleophilic Addition ◽  
Reduction Potential ◽  
Phenyl Group ◽  
Addition Product ◽  
Electrochemical Characteristics ◽  
Photoredox Catalysis ◽  
Reaction Conditions ◽  
State Reduction ◽  
Reducing Properties

A new range of N-phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These N-phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated N-phenylphenothiazines were identified to be highly suitable for photoredox catalysis. The dialkylamino substituents of these N-phenylphenothiazines shift the estimated excited state reduction potential up to −3.0 V (vs SCE). These highly reducing properties allow the addition of methanol to α-methylstyrene as less-activated substrate for this type of reaction. Without the help of an additive, the reaction conditions were optimized to achieve a quantitative yield for the Markovnivkov-type addition product after 20 h of irradiation.

scholarly journals Mutually Isomeric 2- and 4-(3-Nitro-1,2,4-triazol-1-yl)pyrimidines Inspired by an Antimycobacterial Screening Hit: Synthesis and Biological Activity against the ESKAPE Panel of Pathogens

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 666
Author(s):  
Sergey Chuprun ◽  
Dmitry Dar’in ◽  
Elizaveta Rogacheva ◽  
Liudmila Kraeva ◽  
Oleg Levin ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Antibacterial Activity ◽  
Reduction Potential ◽  
Gram Negative ◽  
Reduction Potentials ◽  
Apparent Correlation ◽  
Electron Reduction ◽  
Activity Loss ◽  
Eskape Pathogens ◽  
Bioactivity Profile

Starting from the structure of antimycobacterial screening hit OTB-021 which was devoid of activity against ESKAPE pathogens, we designed, synthesized and tested two mutually isomeric series of novel simplified analogs, 2- and 4-(3-nitro-1,2,4-triazol-1-yl)pyrimidines, bearing various amino side chains. These compounds demonstrated a reverse bioactivity profile being inactive against M. tuberculosis while inhibiting the growth of all ESKAPE pathogens (with variable potency patterns) except for Gram-negative P. aeruginosa. Reduction potentials (E1/2, V) measured for selected compounds by cyclic voltammetry were tightly grouped in the −1.3–−1.1 V range for a reversible single-electron reduction. No apparent correlation between the E1/2 values and the ESKAPE minimum inhibitory concentrations was established, suggesting possible significance of other factors, besides the compounds’ reduction potential, which determine the observed antibacterial activity. Generally, more negative E1/2 values were displayed by 2-(3-nitro-1,2,4-triazol-1-yl)pyrimidines, which is in line with the frequently observed activity loss on moving the 3-nitro-1,2,4-triazol-1-yl moiety from position 4 to position 2 of the pyrimidine nucleus.

scholarly journals Comparison of the Greenhouse Gas Emission Reduction Potential of Energy Communities

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4440 ◽  
Author(s):  
Wouter Schram ◽  
Atse Louwen ◽  
Ioannis Lampropoulos ◽  
Wilfried van Sark
Keyword(s):  
Greenhouse Gas ◽  
Emission Reduction ◽  
Reduction Potential ◽  
Greenhouse Gas Emission ◽  
Heat Pumps ◽  
Solar Irradiation ◽  
Ghg Emission ◽  
Reduction Potentials ◽  
Emission Reduction Potential ◽  
Energy Sharing

In this research, the greenhouse gas (GHG) emission reduction potentials of electric vehicles, heat pumps, photovoltaic (PV) systems and batteries were determined in eight different countries: Austria, Belgium, France, Germany, Italy, the Netherlands, Portugal and Spain. Also, the difference between using prosuming electricity as a community (i.e., energy sharing) and prosuming it as an individual household was calculated. Results show that all investigated technologies have substantial GHG emission reduction potential. A strong moderating factor is the existing electricity generation mix of a country: the GHG emission reduction potential is highest in countries that currently have high hourly emission factors. GHG emission reduction potentials are highest in southern Europe (Portugal, Spain, Italy) and lowest in countries with a high share of nuclear energy (Belgium, France). Hence, from a European GHG emission reduction perspective, it has most impact to install PV in countries that currently have a fossil-fueled electricity mix and/or have high solar irradiation. Lastly, we have seen that energy sharing leads to an increased GHG emission reduction potential in all countries, because it leads to higher PV capacities.

Researches on the Electrolytic Reduction Potentials

1928 ◽  
Vol 4 (7-12) ◽  
pp. 97-100
Author(s):  
Masuzo Shikata ◽  
Isamu Tachi ◽  
Mamoru Watanabe
Keyword(s):  
Electrolytic Reduction ◽  
Reduction Potentials

Preliminary study on alternating thienylene/phenylene copolymers functionalized with an electron-donating or -withdrawing group

2001 ◽  
Vol 16 (5) ◽  
pp. 1235-1237 ◽  
Author(s):  
J. M. Xu ◽  
S. C. Ng ◽  
H. S. O. Chan
Keyword(s):  
Electron Transport ◽  
Reduction Potential ◽  
Saturated Calomel Electrode ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Phenylene Vinylene ◽  
Light Emitting ◽  
Emissive Layer ◽  
Reduction Potentials ◽  
Preliminary Study

Three novel regioregular polymers substituted with electron-donating or -withdrawing groups, poly[1,4-bis(3-X-2,5-thienylene)phenylene-alt-2,5-dioctyl-1,4-phenylene] [PBT(X), X = OMe, H, CN], were synthesized and characterized. They are highly fluorescent, but the absorption wavelength of PBT(CN) and PBT(OMe) are shifted toward the blue and red regions, respectively, with reference to PBT(H). The onset reduction potential of PBT(CN) is –1.11 V versus SCE (saturated calomel electrode), which is higher than that of the cyano derivative of poly(phenylene vinylene), indicating it be a good candidate as electron transport layer. The onset oxidation and reduction potentials of PBT(OMe) (0.96 and –1.28 V versus SCE respectively) suggest it would perform well as emissive layer in light-emitting display applications.

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