| 1. |
- Berg, K. E., et al.
(författare)
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Covalently linked ruthenium(II)-manganese(II) complexes : Distance dependence of quenching and electron transfer
- 2001
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Ingår i: European Journal of Inorganic Chemistry. - 1434-1948 .- 1099-1948. ; 2001:4, s. 1019-1029
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Tidskriftsartikel (refereegranskat)abstract
- Continuing our development of artificial models for photosystem II in green plants, a series of compounds have been prepared in which a RU(bpy)(3)(2+) photosensitizer is covalently Linked to a manganese(II) electron donor. In addition to a trispicolylamine Ligand, two other manganese Ligands, dipicolylamine and aminodiacetic acid, have been introduced in order to study Ligands that are appropriate for the construction of manganese dimers with open coordination sites for the binding of water. Coordination equilibria of the manganese ions were monitored by EPR. The interactions between the ruthenium and manganese moieties were probed by flash photolysis, cyclic voltammetry and steady-state and time-resolved emission measurements. The quenching of the Ru-II excited state by Mn-II was found to be rapid in complexes with short Ru-Mn distances. Nevertheless, each Run species could be photo-oxidized by bimolecular quenching with methylviologen, and the subsequent electron transfer from Mn-II to Ru-III could be monitored.
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| 2. |
- Daniel, Quentin, et al.
(författare)
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Rearranging from 6-to 7-coordination initiates the catalytic activity : An EPR study on a Ru-bda water oxidation catalyst
- 2017
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Ingår i: Coordination chemistry reviews. - : Elsevier. - 0010-8545 .- 1873-3840. ; 346, s. 206-215
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Tidskriftsartikel (refereegranskat)abstract
- The coordination of a substrate water molecule on a metal centered catalyst for water oxidation is a crucial step involving the reorganization of the ligand sphere. This process can occur by substituting a coordinated ligand with a water molecule or via a direct coordination of water onto an open site. In 2009, we reported an efficient ruthenium-based molecular catalyst, Ru-bda, for water oxidation. Despite the impressive improvement in catalytic activity of this type of catalyst over the past years, a lack of understanding of the water coordination still remains. Herein, we report our EPR and DFT studies on Ru-bda (triethylammonium 3-pyridine sulfonate)(2) (1) at its Ru-III oxidation state, which is the initial state in the catalytic cycle for the O-O bond formation. Our investigation suggests that at this III-state, there is already a rearrangement in the ligand sphere where the coordination of a water molecule at the 7th position (open site) takes place under acidic conditions (pH = 1.0) to form a rare 7-coordinated Ru-III species.
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