Interaction between Binuclear Copper(I) Complexes and the Dioxygen Molecule Investigated by Electrochemical Methods

1992 ◽  
Vol 47 (1) ◽  
pp. 109-114 ◽  
Author(s):  
Yuzo Nishida ◽  
Izumi Watanabe ◽  
Kei Unoura
Keyword(s):  
Cyclic Voltammetry ◽  
Thin Layer ◽  
Electrochemical Reduction ◽  
High Reactivity ◽  
Electrochemical Methods ◽  
Tridentate Ligand ◽  
Cyclic Voltammograms ◽  
Binuclear Copper ◽  
Alkyl Chains ◽  
Binucleating Ligands

The cyclic voltammograms of some binuclear copper(II) compounds with binucleating ligands where two molecules of tridentate ligand, N, N -bis(benzimidazol-2-ylmethyl)amine are linked by several alkyl chains, were measured under both argon and dioxygen. The results demonstrate that the binuclear copper(I) species produced by electrochemical reduction exhibit high reactivity towards dioxygen, while the reaction of the corresponding mononuclear species with oxygen is very slow. Thin-layer coulometry ([binuclear copper(I)]/[O2] = 0.47 - 10.6) and thin-layer cyclic voltammetry ([binuclear copper(I)]/[O2] = 4.3 - 10.6 ) revealed that two molecules of the binuclear copper(I) species react with one molecule of dioxygen.

Synthesis and Reactivity of Copper(II) Complexes with New Binucleating Ligands Derived from 16-or 20-Membered N4-Macrocycles

1990 ◽  
Vol 45 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Yuzo Nishida
Keyword(s):  
Catalytic Activity ◽  
Metal Ions ◽  
Binuclear Complex ◽  
Esr Spectra ◽  
Cyclic Voltammograms ◽  
Binuclear Complexes ◽  
Binuclear Copper ◽  
Coordination Sites ◽  
Trinuclear Complexes ◽  
Binucleating Ligands

Abstract New binucleating ligands, (L1) N ,N′,N″,N‴-tetrakis(2-benzimidazolylmethyl)-1,4,9,12-tetra-azacyclohexadecane, and (L2) N ,N′,N″,N‴-tetrakis(2-benzimidazolylmethyl)-1,4,11,14-tetra-azacycloeicosane were prepared. From the reaction mixture of copper(II) salt and the ligand, new binuclear copper(II) complexes, Cu2(L1) (NO3)4 (1), Cu2(L2)(NO3)4 (2), Cu2(L2)Br4 (3), and trinuclear complexes, Cu3(L1)Cl6 (4), and Cu3(L2)Cl6 (5) were obtained. Cyclic voltammograms revealed that the trinuclear complexes 4 and 5 are composed with the binuclear complex (1 or 2) and [CuCl4]2-. The interaction between two metal ions in the binuclear complexes are confirmed on the basis of the ESR spectra. These binuclear complexes exhibit higher catalytic activity for the oxidation of TMPD by O2 molecule than those of structurally rigid binuclear copper(II) complexes and of flexible binuclear complexes in which two copper(II) coordination sites are linked by a single polyatomic chain.

Photochemical and Electrochemical Reduction of Carbon Dioxide Catalyzed by a Polyoxometalate-Organic Photosensitizer Complex

2018 ◽  
Author(s):  
Chandan Dey ◽  
Ronny Neumann
Keyword(s):  
Carbon Dioxide ◽  
Cyclic Voltammetry ◽  
Formic Acid ◽  
Electrochemical Reduction ◽  
Mass Spectroscopy ◽  
Photochemical Reactions ◽  
Reducing Agent ◽  
Covalent Attachment ◽  
Hybrid Complex ◽  
Open Face

<p>A manganese substituted Anderson type polyoxometalate, [MnMo<sub>6</sub>O<sub>24</sub>]<sup>9-</sup>, tethered with an anthracene photosensitizer was prepared and used as catalyst for CO<sub>2</sub> reduction. The polyoxometalate-photosensitizer hybrid complex, obtained by covalent attachment of the sensitizer to only one face of the planar polyoxometalate, was characterized by NMR, IR and mass spectroscopy. Cyclic voltammetry measurements show a catalytic response for the reduction of carbon dioxide, thereby suggesting catalysis at the manganese site on the open face of the polyoxometalate. Controlled potentiometric electrolysis showed the reduction of CO<sub>2</sub> to CO with a TOF of ~15 sec<sup>-1</sup>. Further photochemical reactions showed that the polyoxometalate-anthracene hybrid complex was active for the reduction of CO<sub>2</sub> to yield formic acid and/or CO in varying amounts dependent on the reducing agent used. Control experiments showed that the attachment of the photosensitizer to [MnMo<sub>6</sub>O<sub>24</sub>]<sup>9-</sup> is necessary for photocatalysis.</p><div><br></div>

The influence of the host–guest interaction on the oxidation of natural flavonoid dyes

2011 ◽  
Vol 76 (12) ◽  
pp. 1651-1667 ◽  
Author(s):  
Šárka Ramešová ◽  
Romana Sokolová ◽  
Ilaria Degano ◽  
Magdaléna Hromadová ◽  
Miroslav Gál ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Inclusion Complex ◽  
Fluorescence Intensity ◽  
Oxidation Product ◽  
Aqueous Media ◽  
Electrochemical Methods ◽  
Redox Potentials ◽  
Decomposition Products ◽  
Degradation Processes ◽  
Bioorganic Compounds

The influence of the molecular cavity protection on degradation processes of bioorganic compounds quercetin and luteolin used as the original dyes in old tapestries was studied. The degradation processes were studied by electrochemical methods in aqueous media. The products of the exhaustive electrolysis were separated and identified by GC-MS analysis. Cyclic voltammetry characteristics indicate that the inclusion complex is formed. The inclusion affects the redox potentials of both oxidation waves related to the different dissociation forms of the flavonoid molecule. It was shown that decomposition products formed by the oxidation of quercetin are stabilized in the cavity of β-cyclodextrin, including the main oxidation product 2(3′,4′-dihydroxybenzoyl)-2,4,6-trihydroxybenzofuran-3(2H)-one. The formation of the 1:1 inclusion complex of luteolin with β-cyclodextrin is supported by the enhancement of fluorescence intensity. In the case of quercetin, a decrease of fluorescence intensity occurs when 1:1 inclusion complex with β-cyclodextrin is formed.

Physioelectrochemical investigation of the supercapacitive performance of a ternary nanocomposite by common electrochemical methods and fast Fourier transform voltammetry

2015 ◽  
Vol 39 (12) ◽  
pp. 9454-9460 ◽  
Author(s):  
Javad Shabani Shayeh ◽  
Ali Ehsani ◽  
Ayda Nikkar ◽  
Parviz Norouzi ◽  
Mohammad Reza Ganjali ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Composite Electrode ◽  
Electrochemical Methods ◽  
New Technique ◽  
Supercapacitive Performance ◽  
Ternary Nanocomposite ◽  
A New Technique ◽  
Continuous Cyclic Voltammetry

Fast Fourier transform continuous cyclic voltammetry as a new technique for the explanation of a composite electrode for supercapacitors.

Polyaniline: Influence of Polymerization Current Density

1994 ◽  
Vol 369 ◽  
Author(s):  
Steen Skaarup ◽  
L.M.W.K. Gunaratne ◽  
Keld West ◽  
Birgit Zachau-Christiansen
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
High Current Density ◽  
Electrochemical Polymerization ◽  
Regular Structure ◽  
Spectral Lines ◽  
Complex Nature ◽  
Cyclic Voltammograms ◽  
Layer By Layer ◽  
Current Densities

AbstractPolyaniline has been synthesized in propylene carbonate by galvanostatic electrochemical polymerization at current densities between 16 and 1000 μA/cm2. Earlier results for polypyrrole have shown that low and high current density films have different properties: The films synthesized at low current density have a higher conjugation length and a more regular structure. The corresponding effect in PANI has been investigated by cyclic voltammetry and UV/visible spectroscopy. Simultaneous measurement of cyclic voltammograms and the absorbtion of selected spectral lines is used because of the complex nature of the PANI system which involves several redox systems as well as forms differing in the degree of protonation and morphology.The main result is that the method of galvanostatic synthesis at low current densities (-16 μA/cm2) produces polyaniline polymers of different, more conjugated and more regular structure than those prepared at higher current densities. The standard method of in situ layer-by-layer polymerization of conducting polymers during cyclic voltammetry often results in uncontrolled and unmeasured current densities of 0.5-2 mA/cm2 which produces a film that probably has a less regular structure containing more deviations from ideality.

scholarly journals Electrochemical synthesis of poly(2-methyl aniline): electrochemical and spectroscopic characterization

2001 ◽  
Vol 66 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Aleksandra Buzarovska ◽  
Irena Arsova ◽  
Ljubomir Arsov
Keyword(s):  
Raman Spectroscopy ◽  
Cyclic Voltammetry ◽  
Redox Reactions ◽  
Electrochemical Polymerization ◽  
Spectroscopic Characterization ◽  
Potential Range ◽  
Cyclic Voltammograms ◽  
Impedance Measurements ◽  
Order Of Magnitude ◽  
Poly Aniline

Poly(2-methyl aniline) or poly(ortho-toluidine), as ring substituted derivative of aniline, has been synthesized electrochemically in various concentrations of H2SO4 and HCl, and then characterized by cyclic voltammetry, as well as by impedance and Raman spectroscopy. The cyclic voltammograms of poly(o-toluidine) and poly(aniline) show that the electrochemical polymerization of these two polymers proceeds by almost identical mechanisms. The Raman spectroscopical measurements suggest that the redox reactions of poly(aniline) and poly(o-toluidine) are similar in the potential range between -0.2 and 0.7V vs. SCE. The impedance measurements showed that the conductivity of poly(o-toluidine) is an order of magnitude lower than that of the corresponding poly(aniline) form.

Coordination polymers of 5-substituted 1,2,3,4-tetracyanocyclopentadienides: structural and electrochemical properties of complex compounds of 5-amino- and 5-nitro-tetracyanocyclopentadienide

2021 ◽  
Author(s):  
Patrick Nimax ◽  
Nils Rotthowe ◽  
Florian Zoller ◽  
Tobias Blockhaus ◽  
Friedrich Ernst Wagner ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Mössbauer Spectroscopy ◽  
Electrochemical Properties ◽  
Coordination Polymers ◽  
Mossbauer Spectroscopy ◽  
Complex Compounds ◽  
Electrochemical Methods ◽  
Mößbauer Spectroscopy

Compounds of the 5-amino- (ATCC) and 5-nitro-1,2,3,4-tetracyanocyclopentadienide (NTCC) ligand with iron(II) and iron(III), silver(I) and potassium(I) were prepared and characterized by electrochemical methods using EPR, cyclic voltammetry and Mößbauer spectroscopy...

Copper confined in vesicle-like BCN cavity promotes electrochemical reduction of nitrate to ammonia in water

2021 ◽  
Author(s):  
Xue Zhao ◽  
Guangzhi Hu ◽  
Fang Tan ◽  
Shusheng Zhang ◽  
Xinzhong Wang ◽  
...  
Keyword(s):  
Environmental Pollution ◽  
Electrochemical Reduction ◽  
Value Added ◽  
Electrochemical Methods ◽  
High Concentration ◽  
Bosch Process

Electrochemical methods to convert high-concentration nitrates present in sewage into high-value-added ammonia do not just alleviate the problem of environmental pollution but provide less energy-intensive alternatives to the Haber–Bosch process....

Clam-shaped cyclam-functionalized porphyrin for electrochemical reduction of carbon dioxide

2019 ◽  
Vol 23 (04n05) ◽  
pp. 453-461
Author(s):  
Sumana Tawil ◽  
Hathaichanok Seelajaroen ◽  
Amorn Petsom ◽  
Niyazi Serdar Sariciftci ◽  
Patchanita Thamyongkit
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Cyclic Voltammetry ◽  
Catalytic Activity ◽  
Electrochemical Reduction ◽  
Target Compound ◽  
Faradaic Efficiency ◽  
Controlled Potential Electrolysis ◽  
Improved Stability ◽  
Controlled Potential

A clam-shaped molecule comprising a Zn(II)-porphyrin and a Zn(II)-cyclam is synthesized and characterized. Its electrochemical behavior and catalytic activity for homogeneous electrochemical reduction of carbon dioxide (CO[Formula: see text] are investigated by cyclic voltammetry and compared with those of Zn(II)-meso-tetraphenylporphyrin and Zn(II)-cyclam. Under N2-saturated conditions, cyclic voltammetry of the featured complex has characteristics of its two constituents, but under CO2-saturated conditions, the target compound exhibits significant current enhancement. Iterative reduction under electrochemical conditions indicated the target compound has improved stability relative to Zn(II)-cyclam. Controlled potential electrolysis demonstrates that, without addition of water, methane (CH[Formula: see text] is the only detectable product with 1% Faradaic efficiency (FE). The formation of CH4 is not observed under the catalysis of the Zn(II)-porphyrin benchmark compound, indicating that the CO2-capturing function of the Zn(II)-cyclam unit contributes to the catalysis. Upon addition of 3% v/v water, the electrochemical reduction of CO2 in the presence of the target compound gives carbon monoxide (CO) with 28% FE. Dominance of CO formation under these conditions suggests enhancement of proton-coupled reduction. Integrated action of these Zn(II)-porphyrin and Zn(II)-cyclam units offers a notable example of a molecular catalytic system where the cyclam ring captures and brings CO2 into the proximity of the porphyrin catalysis center.

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