scholarly journals Electrical conductivity in two mixed-valence liquids

2015 ◽  
Vol 17 (21) ◽  
pp. 14107-14114 ◽  
Author(s):  
Wenzhi Yao ◽  
Steven P. Kelley ◽  
Robin D. Rogers ◽  
Thomas P. Vaid
Keyword(s):  
Electrical Conductivity ◽  
Electron Transfer ◽  
Exchange Rate ◽  
Rate Constants ◽  
Room Temperature ◽  
Mixed Valence ◽  
Electrical Current ◽  
Active Species ◽  
Redox Active

Two mixed-valence room-temperature liquids are reported: BuFc–[BuFc+][NTf2−] (BuFc = n-butylferrocene) and TEMPO–[TEMPO+][NTf2−]. Both are conductors of DC electrical current, and their conductivity is modeled based on the electron-transfer self-exchange rate constants of their constituent redox-active species.

Ligand mixed-valence and electrical conductivity in coordination complexes containing a redox-active phenalenol-substituted ligand

2019 ◽  
Vol 48 (23) ◽  
pp. 8053-8056 ◽  
Author(s):  
Sarah Dale ◽  
Nico M. Bonanno ◽  
Mark Pelaccia ◽  
Alan J. Lough ◽  
Atsuhiro Miyawaki ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Mixed Valence ◽  
Closed Shell ◽  
Coordination Complexes ◽  
Low Energy ◽  
Redox Active

Neutral Fe3+ and Co3+ complexes are reported featuring mixed-valent open- and closed-shell ligands, low energy IVCT bands and electrical conductivity.

Synthesis, Crystal Structure and Spectroscopic Studies of New Charge Transfer Compounds Obtained by Reaction of TTF and the Polyoxoanion [Mo6O19]2−

1989 ◽  
Vol 173 ◽  
Author(s):  
C. Bellitto ◽  
D. Attanasio ◽  
M. Bonamico ◽  
V. Fares ◽  
P. Imperatori ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Charge Transfer ◽  
Room Temperature ◽  
Mixed Valence ◽  
Spectroscopic Studies ◽  
Chemical Formula ◽  
Xps Spectra ◽  
Radical Cation Salts ◽  
A Chain

ABSTRACTTwo different tetrathiafulvalene radical cation salts of the [M06O19]2−polyoxoanion have been isolated and characterized. Compound 1 corresponds to the chemical formula (TTF)3[Mo6019]. The crystal structure shows a ID stack of the donor TTF molecule, and each stack fits into channels formed by the anions. Within the stack a chain of trimers is identified, the inter-trimeric distance being 3.51 Å. The I.R., electronic and XPS spectra suggest the compound to be a mixed-valence salt. The electrical conductivity at room temperature is σ = 10−4Ω−1cm−1Compound 2 corresponds to the chemical+formula (TTF)2[M06019] . The compound consists of isolated (TTF+•)2dimers, interspersed with the polyoxoanions. In agreement with this crystal structure the compound is a diamagnetic insulator.

Electron transfer kinetics of cobaloxime complexes

1996 ◽  
Vol 74 (5) ◽  
pp. 658-665 ◽  
Author(s):  
Kefei Wang ◽  
R.B. Jordan
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Rate Constants ◽  
Ph Dependence ◽  
Outer Sphere ◽  
The Self ◽  
Oxidation Of Co ◽  
Reduction Potentials ◽  
Inner Sphere ◽  
Kinetics Of

The rates of oxidation of CoII(dmgBF2)2(OH2)2 by CoIII(NH3)5X2+ (X = Br−, Cl−, and N3−) have been studied at 25 °C in 0.10 M LiClO4. The rate constants are 50 ± 9, 2.6 ± 0.2, and 5.9 ± 1.0 M−1 s−1 for X = Br−, Cl−, and N3−, respectively, in 0.01 M acetate buffer at pH 4.7. The relative rates are consistent with the inner-sphere bridging mechanism established earlier by Adin and Espenson for the analogous reactions of CoII(dmgH)2(OH2)2. The rate constants with CoII(dmgBF2)2(OH2)2 typically are ~103 times smaller and this is attributed largely to the smaller driving force for the CoII(dmgBF2)2(OH2)2 complex. The outer-sphere oxidations of cobalt(II) sepulchrate by CoIII(dmgH)2(OH2)2+ (pH 4.76–7.35, acetate, MES, and PIPES buffers) and CoIII(dmgBF2)2(OH2)2+ (pH 3.3–7.42, chloroacetate, acetate, MES, and PIPES buffers) have been studied. The pH dependence gives the following rate constants (M−1 s−1) for the species indicated: (1.55 ± 0.09) × 105 (CoIII(dmgBF2)2(OH2)2+); (5.5 ± 0.3) × 103 (CoII(dmgH)2(OH2)2+); (3.1 ± 0.5) × 102 (CoIII(dmgH)2(OH2)(OH)); (2.5 ± 0.3) × 102 (CoIII(dmgBF2)2(OH2)(OH)). The known reduction potentials for cobalt(III) sepulchrate and the diaqua complexes, and the self-exchange rate for cobalt(II/III) sepulchrate, are used to estimate the self-exchange rate constants for the dioximate complexes. Comparisons to other reactions with cobalt sepulchrate indicates best estimates of the self-exchange rate constants are ~2.4 × 10−2 M−1 s−1 for CoII/III(dmgH)2(OH2)2and ~5.7 × 10−3 M−1 s−1 for CoII/III(dmgBF2)2(OH2)2. Key words: electron transfer, cobaloxime, inner sphere, outer sphere, self-exchange.

Ammonium tetrathiomolybdate as a novel electrode material for convenient tuning of the kinetics of electrochemical O2 reduction by using iron–porphyrin catalysts

2016 ◽  
Vol 4 (18) ◽  
pp. 6819-6823 ◽  
Author(s):  
Sudipta Chatterjee ◽  
Kushal Sengupta ◽  
Sabyasachi Bandyopadhyay ◽  
Abhishek Dey
Keyword(s):  
Electron Transfer ◽  
Electrode Material ◽  
Deposition Time ◽  
Active Species ◽  
Iron Porphyrin ◽  
Gold Electrodes ◽  
Redox Active ◽  
O2 Reduction ◽  
Ammonium Tetrathiomolybdate ◽  
Kinetics Of

Ammonium tetrathiomolybdate modified gold electrodes can easily tune the rate of electron transfer to the redox active species when the deposition time is varied.

scholarly journals How to Control the Rate of Heterogeneous Electron Transfer Across the Rim of M6L12 and M12L24 Nanospheres

2020 ◽  
Author(s):  
Riccardo Zaffaroni ◽  
Eduard.O. Bobylev ◽  
Plessius, Raoul ◽  
Jarl Ivar van der Vlugt ◽  
Joost reek
Keyword(s):  
Electron Transfer ◽  
Active Species ◽  
Transition Metal Catalysts ◽  
Supramolecular Assemblies ◽  
Fine Tuning ◽  
Transfer Rates ◽  
Heterogeneous Electron Transfer ◽  
Redox Active ◽  
Kinetics Of ◽  
Fine Tune

Catalysis in confined spaces, such as provided by supramolecular cages, is quickly gaining momentum. It allows for second coordination sphere strategies to control the selectivity and activity of transition metal catalysts, beyond the classical methods like fine-tuning the steric and electronic properties of the coordinating ligands. Only a few electrocatalytic reactions within cages have been reported, and there is no information regarding the electron transfer kinetics and thermodynamics of redox-active species encapsulated into supramolecular assemblies. This contribution revolves around the preparation of M<sub>6</sub>L<sub>12 </sub>and larger M<sub>12</sub>L<sub>24</sub> (M= Pd or Pt) nanospheres functionalized with different numbers of redox-active probes encapsulated within their cavity, either in a covalent fashion via different types of linkers (flexible, rigid and conjugated or rigid and non-conjugated) or by supramolecular hydrogen bonding interactions. The redox-probes can be addressed by electrochemical electron transfer across the rim of nanospheres and the thermodynamics and kinetics of this process are described. Our study identifies that the linker type and the number of redox probes within the cage are useful handles to fine-tune the electron transfer rates, paving the way for the encapsulation of electro-active catalysts and electrocatalytic applications of such supramolecular assemblies.

Electron transfer at the class II/III borderline of mixed valency: dependence of rates on solvent dynamics and observation of a localized-to-delocalized transition in freezing solvents

2007 ◽  
Vol 366 (1862) ◽  
pp. 177-185 ◽  
Author(s):  
Starla D Glover ◽  
Benjamin J Lear ◽  
J. Catherine Salsman ◽  
Casey H Londergan ◽  
Clifford P Kubiak
Keyword(s):  
Electron Transfer ◽  
Rate Constants ◽  
Methylene Chloride ◽  
Mixed Valence ◽  
Reorganization Energy ◽  
Frequency Factor ◽  
Intramolecular Electron Transfer ◽  
Solvent Phase ◽  
Valence States ◽  
Solvent Dynamics

The dependence of the rates of intramolecular electron transfer (ET) of mixed-valence complexes of the type {[Ru 3 O(OAc) 6 (CO)(L)] 2 -BL} −1 , where L is the pyridyl ligand and BL is the pyrazine on solvent type and temperature is described. Complexes were reduced chemically to obtain the mixed-valence anions in acetonitrile (CH 3 CN) and methylene chloride (CH 2 Cl 2 ). Rate constants for intramolecular ET were estimated by simulating the observed degree of ν (CO) infrared (IR) bandshape coalescence in the mixed-valence state. In the strongly coupled mixed-valence states of these complexes, the electronic coupling, H AB , approaches λ /2, where λ is the total reorganization energy. The activation energy is thus nearly zero, and rate constants are in the ‘ultrafast’ regime where they depend on the pre-exponential terms within the frequency factor, ν N . The frequency factor contains both external (solvent dynamics) and internal (molecular vibrations) contributions. In general, external solvent motions are slower than internal vibrations, and therefore control ET rates in fluid solution. A profound increase in the degree of ν (CO) IR bandshape coalescence is observed as the temperature approaches the freezing points of the solvents methylene chloride (f.p. −92°C) and acetonitrile (f.p. −44°C). Decoupling the slower solvent motions involved in the frequency factor ν N for ET by freezing the solvent causes a transition from solvent dynamics to internal vibration-limited rates. The solvent phase transition causes a localized-to-delocalized transition in the mixed-valence ions that accelerates the rate of ET.

scholarly journals Ascorbate oxidation by iron, copper and reactive oxygen species: review, model development, and derivation of key rate constants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiaqi Shen ◽  
Paul T. Griffiths ◽  
Steven J. Campbell ◽  
Battist Utinger ◽  
Markus Kalberer ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Ascorbic Acid ◽  
Rate Constants ◽  
Model Development ◽  
Biological Response ◽  
Reactive Oxygen ◽  
Reaction Rates ◽  
Active Species ◽  
Oxygen Species ◽  
Redox Active

AbstractAscorbic acid is among the most abundant antioxidants in the lung, where it likely plays a key role in the mechanism by which particulate air pollution initiates a biological response. Because ascorbic acid is a highly redox active species, it engages in a far more complex web of reactions than a typical organic molecule, reacting with oxidants such as the hydroxyl radical as well as redox-active transition metals such as iron and copper. The literature provides a solid outline for this chemistry, but there are large disagreements about mechanisms, stoichiometries and reaction rates, particularly for the transition metal reactions. Here we synthesize the literature, develop a chemical kinetics model, and use seven sets of laboratory measurements to constrain mechanisms for the iron and copper reactions and derive key rate constants. We find that micromolar concentrations of iron(III) and copper(II) are more important sinks for ascorbic acid (both AH2 and AH−) than reactive oxygen species. The iron and copper reactions are catalytic rather than redox reactions, and have unit stoichiometries: Fe(III)/Cu(II) + AH2/AH−  + O2 → Fe(III)/Cu(II) + H2O2 + products. Rate constants are 5.7 × 104 and 4.7 × 104 M−2 s−1 for Fe(III) + AH2/AH− and 7.7 × 104 and 2.8 × 106 M−2 s−1 for Cu(II) + AH2/AH−, respectively.

scholarly journals How to Control the Rate of Heterogeneous Electron Transfer Across the Rim of M6L12 and M12L24 Nanospheres

2020 ◽  
Author(s):  
Riccardo Zaffaroni ◽  
Eduard.O. Bobylev ◽  
Plessius, Raoul ◽  
Jarl Ivar van der Vlugt ◽  
Joost reek
Keyword(s):  
Electron Transfer ◽  
Active Species ◽  
Transition Metal Catalysts ◽  
Supramolecular Assemblies ◽  
Fine Tuning ◽  
Transfer Rates ◽  
Heterogeneous Electron Transfer ◽  
Redox Active ◽  
Kinetics Of ◽  
Fine Tune

Catalysis in confined spaces, such as provided by supramolecular cages, is quickly gaining momentum. It allows for second coordination sphere strategies to control the selectivity and activity of transition metal catalysts, beyond the classical methods like fine-tuning the steric and electronic properties of the coordinating ligands. Only a few electrocatalytic reactions within cages have been reported, and there is no information regarding the electron transfer kinetics and thermodynamics of redox-active species encapsulated into supramolecular assemblies. This contribution revolves around the preparation of M<sub>6</sub>L<sub>12 </sub>and larger M<sub>12</sub>L<sub>24</sub> (M= Pd or Pt) nanospheres functionalized with different numbers of redox-active probes encapsulated within their cavity, either in a covalent fashion via different types of linkers (flexible, rigid and conjugated or rigid and non-conjugated) or by supramolecular hydrogen bonding interactions. The redox-probes can be addressed by electrochemical electron transfer across the rim of nanospheres and the thermodynamics and kinetics of this process are described. Our study identifies that the linker type and the number of redox probes within the cage are useful handles to fine-tune the electron transfer rates, paving the way for the encapsulation of electro-active catalysts and electrocatalytic applications of such supramolecular assemblies.

Sign in / Sign up

Export Citation Format

Share Document