| 1. |
- Kärkäs, Markus D., et al.
(författare)
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Catalytic Water Oxidation by Ruthenium Complexes Containing Negatively Charged Ligand Frameworks
- 2016
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Ingår i: The chemical record. - : Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. - 1527-8999 .- 1528-0691. ; 16:2, s. 940-963
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Tidskriftsartikel (refereegranskat)abstract
- Artificial photosynthesis represents an attractive way of converting solar energy into storable chemical energy. The H2O oxidation half-reaction, which is essential for producing the necessary reduction equivalents, is an energy-demanding transformation associated with a high kinetic barrier. Herein we present a couple of efficient Ru-based catalysts capable of mediating this four-proton-four-electron oxidation. We have focused on the incorporation of negatively charged ligands, such as carboxylate, phenol, and imidazole, into the catalysts to decrease the redox potentials. This account describes our work in designing Ru catalysts based on this idea. The presence of the negatively charged ligands is crucial for stabilizing the metal centers, allowing for light-driven H2O oxidation. Mechanistic details associated with the designed catalysts are also presented.
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| 2. |
- Liu, Y., et al.
(författare)
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Surface Action Spectroscopy : A review and a Perspective on a New Technique to Study Vibrations at Surfaces
- 2021
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Ingår i: The chemical record. - : Wiley. - 1527-8999 .- 1528-0691. ; 21:6, s. 1270-1283
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Tidskriftsartikel (refereegranskat)abstract
- A new vibrational spectroscopy method aimed at the investigation of solid surfaces in ultrahigh vacuum, called “Surface Action Spectroscopy (SAS)”, is described and the first results are reviewed. This technique is based on ideas and experiments performed in the gas phase. A surface is exposed to a messenger species at low temperature. This messenger species is desorbed via absorption of tunable infrared light from a free-electron laser and the desorption rate of the messenger species is recorded via mass spectrometry. It is shown that the technique is extremely surface sensitive and we discuss the basic mechanisms of the technique. We show a feasibility study on a V2O3(0001) surface, where we know the surface structure. We then proceed to the example of iron oxide films to study the surface structure in parallel with calculations of the surface phonons, which allow us to confirm the surface structure of Fe3O4(111) to be Fetet terminated. It also provides evidence for the so-called biphase structure. To conclude, we discuss possibilities to apply the technique to interesting questions in model and real catalysis, since the technique may provide interesting information independent of long-range order of the sample.
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| 3. |
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| 4. |
- Turunen, Lotta, et al.
(författare)
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Halogen Bonding : An Odd Chemistry?
- 2021
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Ingår i: The chemical record. - : Wiley. - 1527-8999 .- 1528-0691. ; 21:5, s. 1252-1257
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Forskningsöversikt (refereegranskat)abstract
- Halogen bonding is a flourishing field of research, but has for long been little recognized. The same goes for its scientific hero, Odd Hassel, who laid the foundations for all current developments. The crystallographic observation of halogen−oxygen interatomic distances shorter than the sum of the van der Waals radii of the involved atoms, and the interpretation of this phenomenon as a charge-transfer interaction, have been ground-breaking. Today, charge-transfer to a polarized halogen is not any longer seen as “odd”, but is commonly referred to as halogen bonding, and is widely exploited in chemistry. Despite the recognition of Hassel's work with a Nobel prize in 1969, surprisingly little appreciation is given to date to the devoted scientist, who established a world-leading laboratory during one of the darkest eras of history. Herein, we wish to revive the legacy and highlight the impact of Odd Hassel's ground-breaking discoveries.
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| 5. |
- Weissenrieder, Jonas, et al.
(författare)
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Reactivity and Mass Transfer of Low-Dimensional Catalysts
- 2014
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Ingår i: The Chemical Record. - : Wiley. - 1527-8999 .- 1528-0691. ; 14:5, s. 857-868
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mechanisms governing chemical and morphological changes induced by an ambient-pressure gas and how such changes influence the activity of heterogeneous catalysts is central to the formation of a predictive capability for structure-reactivity relationships. With techniques such as ambient-pressure photoelectron spectroscopy, scanning tunneling microscopy, and surface X-ray diffraction, active phases and reaction intermediates can be probed in situ on relevant samples to form a comprehensive picture of this dynamic interplay between gases and surfaces. Of particular interest is the interaction of oxygen and carbon monoxide with catalysts. We will describe how model systems of increased complexity can be used to investigate gas-mediated mass transfer processes that may occur even at relatively modest temperatures. Furthermore, we will discuss how the morphology may be tailored to study specific contributions from defect sites and charge transfer to catalytic activity.
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| 6. |
- Song, Peng, et al.
(författare)
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Photoinduced Electron Transfer in Organic Solar Cells.
- 2016
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Ingår i: The Chemical Record. - : Wiley. - 1527-8999.
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Tidskriftsartikel (refereegranskat)abstract
- Electron transfer (ET) is the key process in light-driven charge separation reactions in organic solar cells. The current review summarizes the progress in theoretical modelling of ET in these materials. First we give an account of ET, with a description originating from Marcus theory. We systematically go through all the relevant parameters and show how they depend on different material properties, and discuss the consequences such dependencies have for the performance of the devices. Finally, we present a set of visualization methods which have proven to be very useful in analyzing the elementary processes in absorption and charge separation events. Such visualization tools help us to understand the properties of the photochemical and photobiological systems in solar cells.
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| 7. |
- Stenkvist, Simon, et al.
(författare)
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Aerobic oxidative N-heterocyclic carbene catalysis
- 2023
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Ingår i: Chemical Record. - 1527-8999. ; 23:7
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Tidskriftsartikel (refereegranskat)abstract
- The ease with which simple starting materials can be transformed into highly functionalized products has made oxidative N-heterocyclic carbene (NHC) catalysis an area of significant interest. However, the use of stoichiometric amounts of high molecular weight oxidants in most reactions generates an undesired equivalent amount of waste. To address this issue, the use of oxygen as the terminal oxidant in NHC catalysis has been developed. Oxygen is attractive due to its low cost, low molecular weight, and ability to generate water as the sole by-product. However, molecular oxygen is challenging to use as a reagent in organic synthesis due to its unreactive ground state, which often requires reactions to be run at high temperatures and results in the formation of kinetic side-products. This review covers the development of aerobic oxidative carbene catalysis, including NHC-catalyzed reactions with oxygen, strategies for oxygen activation, and selectivity issues under aerobic conditions.
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