UV-vis spectroelectrochemistry is assessed as a tool for the diagnosis and quantitative investigation of the incidence of comproportionation in multielectron transfer processes. Thus, the sensitivity of the limiting current chronoabsorptometric signals related to the different redox states to the comproportionation kinetics is studied theoretically for different working modes (normal and parallel light beam arrangements) and mass transport regimes (from semi-infinite to thin layer diffusion). The theoretical results are applied to the spectroelectrochemical study of the two-electron reduction of the anthraquinone-2-sulfonate in alkaline aqueous solution, tuning the thermodynamic favorability of the comproportionation reaction through the electrolyte cation. The quantitative analysis of the experimental results reveals the occurrence of comproportionation in the three media examined, showing different kinetics depending on the cationic species in solution.
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http://dx.doi.org/10.1021/acs.analchem.2c02523 | DOI Listing |
Anal Chem
September 2022
Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, 30100 Murcia, Spain.
UV-vis spectroelectrochemistry is assessed as a tool for the diagnosis and quantitative investigation of the incidence of comproportionation in multielectron transfer processes. Thus, the sensitivity of the limiting current chronoabsorptometric signals related to the different redox states to the comproportionation kinetics is studied theoretically for different working modes (normal and parallel light beam arrangements) and mass transport regimes (from semi-infinite to thin layer diffusion). The theoretical results are applied to the spectroelectrochemical study of the two-electron reduction of the anthraquinone-2-sulfonate in alkaline aqueous solution, tuning the thermodynamic favorability of the comproportionation reaction through the electrolyte cation.
View Article and Find Full Text PDFAcc Chem Res
March 2015
Yale Energy Sciences Institute and Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States.
Catalysts for light-driven water oxidation are a critical component for development of solar fuels technology. The multielectron redox chemistry required for this process has been successfully deployed on a global scale in natural photosynthesis by green plants and cyanobacteria using photosystem II (PSII). PSII employs a conserved, cuboidal Mn4CaOX cluster called the O2-evolving complex (OEC) that offers inspiration for artificial O2-evolution catalysts.
View Article and Find Full Text PDFInorg Chem
April 2009
Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.
The self-assembly of two rectangular compounds [{(CO)(3)Re(mu-QL)Re(CO)(3)}(2)(mu-bpy)(2)] (1, QL = 6,7-dimethyl 1,4-dioxido-9,10-anthraquinone (QL(1)); 2, QL = 1,4-dioxido-9,10-anthraquinone (QL(2)), bpy = 4,4'-bipyridine) via an orthogonal-bonding approach was achieved in high yields. Their structures were characterized by single-crystal X-ray diffraction analysis. The rectangles exhibited multielectron-redox properties.
View Article and Find Full Text PDFInorg Chem
October 2008
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas 76019-0065, USA.
The mononuclear ruthenium complex [(bpy) 2Ru(tatpp)] (2+) ( 1 (2+); bpy is 2,2'-bipyridine and tatpp is 9,11,20,22-tetra-aza-tetrapyrido[3,2-a:2'3'-c:3'',2''-l:2''',3''']-pentacene) undergoes up to four reversible tatpp ligand-based reductions as determined by electrochemistry in aqueous solution. Specific redox and protonation states of this complex were generated by stoichiometric chemical reduction with cobaltocene and protonation with trifluoroacetic acid in acetonitrile. These species exhibit unique UV-visible absorption spectra, which are used to determine the speciation in aqueous media as a function of the potential during the electrochemical reduction.
View Article and Find Full Text PDFJ Am Chem Soc
March 2006
Department of Chemistry, University of Vermont, Burlington, Vermont 05405, USA.
An integrated approach to the control of deltaE(1/2) values, and therefore comproportionation equilibria, through medium effects was delineated for multi-step redox reactions involving cationic products. deltaE(1/2) values (defined as E(1/2)(2+/1+) - E(1/2)(1+/0)) of the two one-electron oxidations of bis(fulvalene)dinickel, 1, were measured under 45 different conditions of solvent and supporting electrolyte. The smallest value, 212 mV, was found in anisole/0.
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