| 1. |
- Arafa, Wael A. A., et al.
(författare)
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Dinuclear manganese complexes for water oxidation : evaluation of electronic effects and catalytic activity
- 2014
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 16:24, s. 11950-11964
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Tidskriftsartikel (refereegranskat)abstract
- During recent years significant progress has been made towards the realization of a sustainable and carbon-neutral energy economy. One promising approach is photochemical splitting of H2O into O-2 and solar fuels, such as H-2. However, the bottleneck in such artificial photosynthetic schemes is the H2O oxidation half reaction where more efficient catalysts are required that lower the kinetic barrier for this process. In particular catalysts based on earth-abundant metals are highly attractive compared to catalysts comprised of noble metals. We have now synthesized a library of dinuclear Mn-2 (II,III) catalysts for H2O oxidation and studied how the incorporation of different substituents affected the electronics and catalytic efficiency. It was found that the incorporation of a distal carboxyl group into the ligand scaffold resulted in a catalyst with increased catalytic activity, most likely because of the fact that the distal group is able to promote proton-coupled electron transfer (PCET) from the high-valent Mn species, thus facilitating O-O bond formation.
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| 2. |
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| 3. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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Chemical and Photochemical Water Oxidation Mediated by an Efficient Single-Site Ruthenium Catalyst
- 2016
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 9:24, s. 3448-3456
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Tidskriftsartikel (refereegranskat)abstract
- Water oxidation is a fundamental step in artificial photosynthesis for solar fuels production. In this study, we report a single-site Ru-based water oxidation catalyst, housing a dicarboxylate-benzimidazole ligand, that mediates both chemical and light-driven oxidation of water efficiently under neutral conditions. The importance of the incorporation of the negatively charged ligand framework is manifested in the low redox potentials of the developed complex, which allows water oxidation to be driven by the mild one-electron oxidant [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine). Furthermore, combined experimental and DFT studies provide insight into the mechanistic details of the catalytic cycle.
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| 4. |
- Abdel-Magied, Ahmed F., et al.
(författare)
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Substituent Effects in Molecular Ruthenium Water Oxidation Catalysts Based on Amide Ligands
- 2017
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Ingår i: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 9:9, s. 1583-1587
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Tidskriftsartikel (refereegranskat)abstract
- The production of clean and sustainable energy is considered as one of the most urgent issues for our society. Mastering the oxidation of water to dioxygen is essential for the production of solar fuels. A study of the influence of the substituents on the catalytic activity of a series of mononuclear Ru complexes (2a-e) based on a tetradentate ligand framework is presented. At neutral pH, using [Ru(bpy)(3)](PF6)(3) (bpy=2,2'-bipyridine) as the terminal oxidant, a good correlation between the turnover frequency (TOF) and the Hammett sigma(meta) parameters was obtained. Additionally, a general pathway for the deactivation of Ru-based catalysts 2a-e during the catalytic oxidation of water through poisoning by carbon monoxide was demonstrated. These results highlight the importance of ligand design for fine-tuning the catalytic activity of water oxidation catalysts.
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| 5. |
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| 6. |
- Das, Biswanath, et al.
(författare)
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Water oxidation catalyzed by molecular di- and nonanuclear Fe complexes: importance of a proper ligand framework
- 2016
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Ingår i: Dalton Transactions. - : ROYAL SOC CHEMISTRY. - 1477-9226 .- 1477-9234. ; 45:34, s. 13289-13293
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of two molecular iron complexes, a dinuclear iron(III,III) complex and a nonanuclear iron complex, based on the di-nucleating ligand 2,2-(2-hydroxy-5-methyl-1,3-phenylene)bis(1H-benzo[d]imidazole-4-carboxylic acid) is described. The two iron complexes were found to drive the oxidation of water by the one-electron oxidant [Ru(bpy)(3)](3+).
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| 7. |
- Hagelin, H., et al.
(författare)
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Investigation of the palladium catalyzed aromatic coupling of pyridine derivatives
- 2000
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Ingår i: Journal of Molecular Catalysis A. - 1381-1169 .- 1873-314X. ; 164:1-2, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- The coupling reaction of 4-methylpyridine to form 4,4 ' -dimethyl-2,2 ' -bipyridine using a carbon-supported palladium catalyst was studied. Whereas previous research indicated that the reaction is catalyzed by palladium(0), we have found evidence that the reaction is catalyzed by palladium(II). Although oxygen can be used as the oxidative agent, the reaction is ultimately Limited by catalyst deactivation. The major source of deactivation is most likely depletion of the palladium(II) oxide. The catalyst is reduced during the reaction and in the case of the oxygen-treated catalyst a small amount of palladium appears to be dissolved. In an investigation of the catalyst using X-ray photoelectron spectroscopy (XPS) and solid state nuclear magnetic resonance (NMR) it was found that deactivation is also caused by poisoning, the poison being either the product and/or the by-product.
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