Here, a critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s–1, faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L)2] (bpH2cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediates O–O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.
Shaffer, David W., et al. "Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts." Journal of the American Chemical Society, vol. 139, no. 43, Sep. 2017. https://doi.org/10.1021/jacs.7b06096
Shaffer, David W., Xie, Yan, Szalda, David J., & Concepcion, Javier J. (2017). Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts. Journal of the American Chemical Society, 139(43). https://doi.org/10.1021/jacs.7b06096
Shaffer, David W., Xie, Yan, Szalda, David J., et al., "Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts," Journal of the American Chemical Society 139, no. 43 (2017), https://doi.org/10.1021/jacs.7b06096
@article{osti_1405937,
author = {Shaffer, David W. and Xie, Yan and Szalda, David J. and Concepcion, Javier J.},
title = {Lability and Basicity of Bipyridine-Carboxylate-Phosphonate Ligand Accelerate Single-Site Water Oxidation by Ruthenium-Based Molecular Catalysts},
annote = {Here, a critical step in creating an artificial photosynthesis system for energy storage is designing catalysts that can thrive in an assembled device. Single-site catalysts have an advantage over bimolecular catalysts because they remain effective when immobilized. Hybrid water oxidation catalysts described here, combining the features of single-site bis-phosphonate catalysts and fast bimolecular bis-carboxylate catalysts, have reached turnover frequencies over 100 s–1, faster than both related catalysts under identical conditions. The new [(bpHc)Ru(L)2] (bpH2cH = 2,2'-bipyridine-6-phosphonic acid-6'-carboxylic acid, L = 4-picoline or isoquinoline) catalysts proceed through a single-site water nucleophilic attack pathway. The pendant phosphonate base mediates O–O bond formation via intramolecular atom-proton transfer with a calculated barrier of only 9.1 kcal/mol. Additionally, the labile carboxylate group allows water to bind early in the catalytic cycle, allowing intramolecular proton-coupled electron transfer to lower the potentials for oxidation steps and catalysis. That a single-site catalyst can be this fast lends credence to the possibility that the oxygen evolving complex adopts a similar mechanism.},
doi = {10.1021/jacs.7b06096},
url = {https://www.osti.gov/biblio/1405937},
journal = {Journal of the American Chemical Society},
issn = {ISSN 0002-7863},
number = {43},
volume = {139},
place = {United States},
publisher = {American Chemical Society (ACS)},
year = {2017},
month = {09}}
