Electrochemistry of Copper

Rorabacher, D. B.; Schroeder, Ronald R.

doi:10.1002/9783527610426.bard072407

Cited by 11 publications

(11 citation statements)

References 183 publications

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“…We hypothesized that triazolylmethylamines stabilize Cu(I) against disproportionation in water/methanol mixtures. Cu(I) ions disproportionate in water, or water/methanol mixtures, to Cu(II) and Cu(0) . As a consequence of the tendency for Cu(I) to disproportionate, the cyclic voltammogram (CV) obtained from CuSO 4 (5 mM) in a mixture of H 2 O:CH 3 OH (9:4, v:v) gave two oxidation and reduction peaks (Figure S8).…”

Section: Resultsmentioning

confidence: 99%

“…Cu(I) ions disproportionate in water, or water/methanol mixtures, to Cu(II) and Cu(0). 69 As a consequence of the tendency for Cu(I) to disproportionate, the cyclic voltammogram (CV) obtained from CuSO 4 (5 mM) in a mixture of H 2 O:CH 3 OH (9:4, v:v) gave two oxidation and reduction peaks (Figure S8). The CV of CuSO 4 (5 mM) and N(C 3 N 3 ) 3 (10 mM) in a mixture of H 2 O:CH 3 OH (9:4, v:v), however, gave only one peak (Figure 4f) corresponding to the reduction of Cu(II) to Cu(I).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Autocatalytic Cycles in a Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction

et al. 2018

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This work describes the autocatalytic copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction between tripropargylamine and 2-azidoethanol in the presence of Cu(II) salts. The product of this reaction, tris-(hydroxyethyltriazolylmethyl)amine (N(CN)), accelerates the cycloaddition reaction (and thus its own production) by two mechanisms: (i) by coordinating Cu(II) and promoting its reduction to Cu(I) and (ii) by enhancing the catalytic reactivity of Cu(I) in the cycloaddition step. Because of the cooperation of these two processes, a rate enhancement of >400× is observed over the course of the reaction. The kinetic profile of the autocatalysis can be controlled by using different azides and alkynes or ligands (e.g., ammonia) for Cu(II). When carried out in a layer of 1% agarose gel, and initiated by ascorbic acid, this autocatalytic reaction generates an autocatalytic front. This system is prototypical of autocatalytic reactions where the formation of a product, which acts as a ligand for a catalytic metal ion, enhances the production and activity of the catalyst.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Autocatalytic Cycles in a Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction

et al. 2018

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“…Such coordination environments are known to have a high formal Cu(II/I) redox potential keeping copper preferably in its Cu(I) oxidation state by destabilizing the Cu(II) oxidation state . This effect has been found to be pronounced for tripodal ligands with increasing numbers of sulfur atoms, especially thioether donors (see Rorabacher and Schroeder and references therein). In this context, it is noteworthy that 3- and 4-fold Cu(I) coordinated geometry was found to dominate Cu(I) speciation in HA equilibrated under oxic conditions, indicating a high stability of these Cu(I)-HA complexes against oxidation (SI Table S3).…”

Section: Resultsmentioning

confidence: 99%

Copper Redox Transformation and Complexation by Reduced and Oxidized Soil Humic Acid. 1. X-ray Absorption Spectroscopy Study

Fulda

Voegelin

Maurer

et al. 2013

Environ. Sci. Technol.

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Natural organic matter (NOM) exerts strong influence on copper speciation and bioavailability in soils and aquatic systems. In redox-dynamic environments, electron transfer reactions between copper and redox-active moieties of NOM may trigger Cu(I) and Cu(0) formation. To date, little is known about Cu-NOM redox interactions and Cu(I) binding to NOM. Here, we present X-ray absorption spectroscopy results on copper redox transformations upon addition of Cu(II) or Cu(I) to untreated and electrochemically reduced soil humic acid (HA) under oxic and anoxic conditions. Both untreated and reduced HA mediated copper redox transformations. Under anoxic conditions, Cu(II) and Cu(I) added to reduced HA were primarily complexed and thereby stabilized as Cu(I)-HA at low loadings, whereas high copper loadings resulted in the additional formation of Cu(0) nanoparticles (16-64% of total copper). Cu(I) bound to HA was predominantly 2-fold coordinated and to a lower extent 3- to 4-fold coordinated, with a contribution of at least one nitrogen and/or sulfur ligand group. Under oxic conditions, Cu(II)-HA complexes prevailed, but smaller fractions of copper were also stabilized as Cu(I)-HA in a 3- to 4-fold coordination. Our results show that Cu-HA redox interactions are strongly affected by binding of Cu(II) and Cu(I) to HA and that HA contributes to the stabilization of Cu(I) against disproportionation.

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“…The Cu 2+ /Cu + couple makes copper promising for constructing redox‐active agents [28] . Cu 2+ complexes have a strong PRE effect and thus quench the MR signal of neighboring 19 F nuclei.…”

Section: Copper‐based Agentsmentioning

confidence: 99%

Design Strategies for Responsive Fluorine‐19 Magnetic Resonance Probes Using Paramagnetic Metal Complexes

2022

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Magnetic resonance imaging (MRI) is a powerful and widely used in vivo imaging technique that enables whole body imaging without ionizing radiation. In clinical practice, 1 H MRI is employed for imaging anatomical and physiological states via monitoring of protons in water and lipids. In order to monitor biochemical processes at the molecular level, several research groups are exploring responsive MRI agents that alter their signal upon interaction with an analyte or biological environment of interest. Fluorine ( 19 F) MRI agents are promising due to the 19 F nucleus having similar magnetic resonance (MR) properties to proton and the absence of endogenous 19 F in living systems, resulting in no background signal. In order to make responsive 19 F MR agents for molecular imaging and analysis, fluorinated platforms must be developed in which their 19 F MR signal changes after interacting with a target analyte. A promising strategy is to use paramagnetic metals to modulate the 19 F MR signal by altering the relaxation rates and/or chemical shift of an appended 19 F imaging tag. In this concept, we provide an overview of the theoretical principles and molecular design strategies that have been exploited in the design of responsive 19 F MR agents, with a specific focus on agents based on small molecule paramagnetic metal ion chelates.

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Electrochemistry of Copper

Abstract: The sections in this article are Introduction Oxidation States of Copper Reference Standards for Potential Values in Nonaqueous Solvent Studies Methods Used for Potential Measurements Potentials Involving Solvated Copper Species Electrochemical Considerations for Copper( … Show more

Cited by 11 publications

References 183 publications

Autocatalytic Cycles in a Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction

Autocatalytic Cycles in a Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction

Copper Redox Transformation and Complexation by Reduced and Oxidized Soil Humic Acid. 1. X-ray Absorption Spectroscopy Study

Design Strategies for Responsive Fluorine‐19 Magnetic Resonance Probes Using Paramagnetic Metal Complexes

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