scholarly journals Analyzing mechanisms in Co(i) redox catalysis using a pattern recognition platform

2021 ◽  
Vol 12 (13) ◽  
pp. 4771-4778
Author(s):  
Tianhua Tang ◽  
Christopher Sandford ◽  
Shelley D. Minteer ◽  
Matthew S. Sigman
Keyword(s):  
Pattern Recognition ◽  
Electron Transfer ◽  
Linear Regression ◽  
Electrochemical Reduction ◽  
Kinetic Studies ◽  
Outer Sphere ◽  
Cobalt Complexes ◽  
Transfer Mechanism ◽  
Redox Catalysis ◽  
Electron Transfer Mechanism

Through kinetic studies combining electroanalytical techniques with multivariable linear-regression (MLR) analysis, a pattern recognition platform is established to determine the electron-transfer mechanism (inner-sphere or outer-sphere) of an electrochemical reduction of benzyl bromides, mediated by different cobalt complexes.

scholarly journals Analyzing Mechanisms in Co(I) Redox Catalysis Using a Pattern Recognition Platform

2020 ◽  
Author(s):  
Tianhua Tang ◽  
Christopher Sandford ◽  
Shelley D. Minteer ◽  
Matthew Sigman
Keyword(s):  
Pattern Recognition ◽  
Bond Cleavage ◽  
Linear Regression Analysis ◽  
Benzyl Bromide ◽  
Kinetic Studies ◽  
Outer Sphere ◽  
Redox Catalysis ◽  
Tridentate Ligands ◽  
Electron Transfer Mechanism ◽  
Multivariable Linear Regression Analysis

Redox catalysis has been broadly utilized in electrochemical synthesis due to its kinetic advantages over direct electrolysis. The appropriate choice of redox mediator can avoid electrode passivation and overpotential, which strongly inhibit the efficient activation of substrates in electrolysis. Despite the benefits brought by redox catalysis, establishing the precise nature of substrate activation remains challenging. Herein, we determine that a Co(I) complex bearing two <i>N</i>,<i>N</i>,<i>N</i>-tridentate ligands acts as a competent redox catalyst for the reduction of benzyl bromide substrates. Kinetic studies combining electroanalytical techniques with multivariable linear-regression analysis were conducted, disclosing an outer-sphere electron-transfer mechanism, which occurs in concert with C–Br bond cleavage. Furthermore, we apply a pattern recognition platform to distinguish between mechanisms in the activation of benzyl bromides, found to be dependent on the ligation state of the cobalt(I) center and ligand used.

scholarly journals Analyzing Mechanisms in Co(I) Redox Catalysis Using a Pattern Recognition Platform

2020 ◽  
Author(s):  
Tianhua Tang ◽  
Christopher Sandford ◽  
Shelley D. Minteer ◽  
Matthew Sigman
Keyword(s):  
Pattern Recognition ◽  
Bond Cleavage ◽  
Linear Regression Analysis ◽  
Benzyl Bromide ◽  
Kinetic Studies ◽  
Outer Sphere ◽  
Redox Catalysis ◽  
Tridentate Ligands ◽  
Electron Transfer Mechanism ◽  
Multivariable Linear Regression Analysis

Redox catalysis has been broadly utilized in electrochemical synthesis due to its kinetic advantages over direct electrolysis. The appropriate choice of redox mediator can avoid electrode passivation and overpotential, which strongly inhibit the efficient activation of substrates in electrolysis. Despite the benefits brought by redox catalysis, establishing the precise nature of substrate activation remains challenging. Herein, we determine that a Co(I) complex bearing two <i>N</i>,<i>N</i>,<i>N</i>-tridentate ligands acts as a competent redox catalyst for the reduction of benzyl bromide substrates. Kinetic studies combining electroanalytical techniques with multivariable linear-regression analysis were conducted, disclosing an outer-sphere electron-transfer mechanism, which occurs in concert with C–Br bond cleavage. Furthermore, we apply a pattern recognition platform to distinguish between mechanisms in the activation of benzyl bromides, found to be dependent on the ligation state of the cobalt(I) center and ligand used.

Cycloaddition of CO2 with epoxides and esterification reactions using the porous redox catalyst Co-POM@MIL-101(Cr)

2019 ◽  
Vol 43 (39) ◽  
pp. 15585-15595 ◽  
Author(s):  
Afsaneh Marandi ◽  
Mehrnaz Bahadori ◽  
Shahram Tangestaninejad ◽  
Majid Moghadam ◽  
Valiollah Mirkhani ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Acetic Acid ◽  
Catalytic Activity ◽  
Outer Sphere ◽  
Transfer Mechanism ◽  
Solvent Free ◽  
Electron Transfer Mechanism ◽  
Redox Catalyst ◽  
Redox Pair ◽  
Esterification Reactions

The catalytic activity of the Co-POM@MIL-101(Cr) composite in solvent-free cycloaddition of CO2 to epoxides and esterification of acetic acid with alcohols is due to an outer-sphere electron transfer mechanism using the Co(iii)/Co(ii) redox pair.

scholarly journals Single-electron reduction of quinone and nitroaromatic xenobiotics by recombinant rat neuronal nitric oxide synthase.

2013 ◽  
Vol 60 (2) ◽  
Author(s):  
Žilvinas Anusevičius ◽  
Henrikas Nivinskas ◽  
Jonas Šarlauskas ◽  
Marie-Agnes Sari ◽  
Jean-Luc Boucher ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Electron Transfer ◽  
Nitric Oxide Synthase ◽  
Neuronal Nitric Oxide Synthase ◽  
Outer Sphere ◽  
Transfer Mechanism ◽  
Single Electron ◽  
Electron Transfer Mechanism ◽  
Electron Reduction ◽  
Oxide Synthase

We examined the kinetics of single-electron reduction of a large number of structurally diverse quinones and nitroaromatic compounds, including a number of antitumour and antiparasitic drugs, and nitroaromatic explosives by recombinant rat neuronal nitric oxide synthase (nNOS, EC 1.14.13.39), aiming to characterize the role of nNOS in the oxidative stress-type cytotoxicity of the above compounds. The steady-state second-order rate constants (kcat/Km) of reduction of the quinones and nitroaromatics varied from 10² M⁻¹s⁻¹ to 10⁶ M⁻¹s⁻¹, and increased with an increase in their single-electron reduction potentials (E¹₇). The presence of Ca²⁺/calmodulin enhanced the reactivity of nNOS. These reactions were consistent with an 'outer sphere' electron-transfer mechanism, considering the FMNH∙/FMNH₂ couple of nNOS as the most reactive reduced enzyme form. An analysis of the reactions of nNOS within the 'outer sphere' electron-transfer mechanism gave the approximate values of the distance of electron transfer, 0.39-0.47 nm, which are consistent with the crystal structure of the reductase domain of nNOS. On the other hand, at low oxygen concentrations ([O₂] = 40-50 μM), nNOS performs a net two-electron reduction of quinones and nitroaromatics. This implies that NOS may in part be responsible for the bioreductive alkylation by two-electron reduced forms of antitumour aziridinyl-substituted quinones under a modest hypoxia.

scholarly journals RuIII(edta) complexes as molecular redox catalysts in chemical and electrochemical reduction of dioxygen and hydrogen peroxide: inner-sphere versus outer-sphere mechanism

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21359-21366
Author(s):  
Debabrata Chatterjee ◽  
Marta Chrzanowska ◽  
Anna Katafias ◽  
Maria Oszajca ◽  
Rudi van Eldik
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Electrochemical Reduction ◽  
Molecular Oxygen ◽  
Outer Sphere ◽  
Transfer Processes ◽  
Edta Complexes ◽  
Inner Sphere ◽  
Electron Transfer Processes ◽  
Sphere Mechanism

[RuII(edta)(L)]2–, where edta4– =ethylenediaminetetraacetate; L = pyrazine (pz) and H2O, can reduce molecular oxygen sequentially to hydrogen peroxide and further to water by involving both outer-sphere and inner-sphere electron transfer processes.

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