A Practical Beginner’s Guide to Cyclic Voltammetry

A Practical Beginner’s Guide to Cyclic Voltammetry

Noemie Elgrishi, Kelley J. Rountree, Brian D. McCarthy, Eric S. Rountree, Thomas T. Eisenhart, and Jillian L. Dempsey*

 J. Chem. Ed. ASAP
pubs.acs.org/doi/pdf/10.1021/acs.jchemed.7b00361

Abstract:
 

Despite the growing popularity of cyclic voltammetry, many students do not receive formalized training in this technique as part of their coursework. Confronted with self-instruction, students can be left wondering where to start. Here, a short introduction to cyclic voltammetry is provided to help the reader with data acquisition and interpretation. Tips and common pitfalls are provided, and the reader is encouraged to apply what is learned in short, simple training modules provided in the Supporting Information. Armed with the basics, the motivated aspiring electrochemist will find existing resources more accessible and will progress much faster in the understanding of cyclic voltammetry.

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Potential of Ru(III/II) Couple Increases with Increased Sterics of Scorpionate Ligands

http://www.sciencedirect.com/science/article/pii/S0020169313000674.

Volume 405, 24 August 2013, Pages 470–476

Synthesis and electrochemical characterization of [Ru(NCCH₃)₆]²⁺, tris(acetonitrile) tris(pyrazolyl)borate, and tris(acetonitrile) tris(pyrazolyl)methane ruthenium(II) complexes

• Christopher C. Underwood,
• Bradley S. Stadelman,
• Mark L. Sleeper,
• Julia L. Brumaghim^,

http://dx.doi.org/10.1016/j.ica.2013.02.027

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Abstract

Tris(acetonitrile) tris(pyrazolyl)borato- and tris(pyrazolyl)methano ruthenium(II) complexes would make good synthons in ruthenium chemistry for synthesis of catalysts and DNA binding drugs. However, these complexes are not widely used as starting materials due to the long reaction times and multiple synthetic steps required or the lack of their successful synthesis. We have developed a new synthesis for the ruthenium(II) acetonitrile complex [Ru(NCCH₃)₆]²⁺ with noncoordinating BF₄⁻ or OTf (OTf = trifluoromethanesulfonate) counterions. Using this [Ru(NCCH₃)₆]²⁺ complex, the previously reported tris(acetonitrile) tris(pyrazolyl)borato ruthenium(II) complexes [Tp^RRu(NCCH₃)₃]⁺ (Tp^R = tris(pyrazolyl)borate; R = H, Me) and the unreported tris(acetonitrile) tris(pyrazolyl)borato ruthenium(II) complex (R = Ph) have been synthesized using an improved synthetic pathway that reduces the number of required steps by up to six and the average synthesis times by up to 45 h. Novel tris(acetonitrile) tris(pyrazolyl)methano ruthenium(II) complexes of the formula [Tpm^RRu(NCCH₃)₃]²⁺ (Tpm^R = tris(pyrazolyl)methane; R = Me, Ph) have also been synthesized in one step in 12 h using this method. Cyclic voltammetry studies of the synthesized complexes show that Ru^2+/3+ redox potentials generally increase with increasing steric bulk of the Tp^R or Tpm^R ligand. The ability to sterically tune Ru^2+/3+ redox potentials may be used to promote catalysis development and in the development of ruthenium-based drugs.

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Graphical abstract

We report improved syntheses for [Ru(NCCH₃)₆]²⁺ and complexes of the formula [Tp^RRu(NCCH₃)₃]⁺ (Tp^R = tris(pyrazolyl)borate; R = H, Me, Ph), as well as syntheses for unreported [Tpm^RRu(NCCH₃)₃]²⁺ (Tpm^R = tris(pyrazolyl)methane; R = Me, Ph) complexes. Electrochemical studies indicate that the Ru^2+/3+ redox potentials of these complexes vary by up to 427 mV, a trait that may be useful for ruthenium-based drug and catalysis development.

Polymer Coordination Promotes Selective CO2 Reduction by Cobalt Phthalocyanine

Polymer Coordination Promotes Selective CO2 Reduction by Cobalt Phthalocyanine

Wesley W Kramer and Charles McCrory

Chem. Sci., 2016, Accepted Manuscript
DOI: 10.1039/C5SC04015A
Received 22 Oct 2015, Accepted 01 Feb 2016

Cobalt phthalocyanine (CoPc) is a known electrocatalyst for the carbon dioxide reduction reaction (CO2RR) that, when adsorbed onto edge-plane graphite (EPG) electrodes, shows modest activity and selectivity for CO production along with co-generation of H2. In contrast, electrodes modified with CoPc immobilized in a poly-4-vinylpridine (P4VP) film show dramatically enhanced activity and selectivity compared to those modified CoPc alone. CoPc-P4VP films display a Faradaic efficiency of ~90% for CO production, with a turnover frequency of 4.8 s-1 at just -0.75 V vs RHE. Two properties of P4VP contribute to enhancing the activity of CoPc; (1) the ability of individual pyridine residues to coordinate to CoPc and (2) the high concentration of uncoordinated pyridine residues throughout the film which may enhance the catalytic activity of CoPc through secondary and other outer coordination sphere effects. Electrodes modified with polymer-free, five-coordinate CoPc(py) films (py = pyridine) and with CoPc catalysts immobilized in non-coordinating poly-2-vinylpyridine films were prepared to independently investigate the role that each property plays in enhancing CO2RR performance of CoPc-P4VP. These studies show that a synergistic relationship between the primary and outer coordination sphere effects is responsible for the enhanced catalytic activity of CoPc when embedded in the P4VP membrane.