| 1. |
- Cousins, David L., et al.
(author)
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Pyrimidin-6-yl Trifluoroborate Salts as Versatile Templates for Heterocycle Synthesis
- 2021
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 133:17, s. 9498-9501
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Journal article (peer-reviewed)abstract
- We report a novel and general method to access a highly under‐studied privileged scaffold – pyrimidines bearing a trifluoroborate at C4, and highlight the broad utility of these intermediates in a rich array of downstream functionalization reactions. This chemistry is underpinned by the unique features of the trifluoroborate group; its robustness provides an opportunity to carry out chemoselective reactions at other positions on the pyrimidine while providing a pathway for elaboration at the C‐B bond when suitably activated.
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| 2. |
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| 3. |
- Goesten, Maarten, et al.
(author)
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Cesium's off-the-map valence orbital
- 2017
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In: Angewandte Chemie. - : Wiley. - 1521-3773 .- 1433-7851 .- 0044-8249 .- 1521-3757.
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Journal article (peer-reviewed)abstract
- The Td-symmetric [CsO4]+ ion, featuring Cs in an oxidation state of 9, is computed to be a minimum. Cs uses outer core 5s and 5p orbitals to bind the oxygens. The valence Cs 6s orbital lies too high to be involved in bonding, and contributes to Rydberg levels only. From a Molecular Orbital perspective, the bonding scheme reminds of XeO4: an octet of electrons to bind electronegative ligands, and no low-lying acceptor orbitals on the central atom. In this sense, Cs+ resembles hypervalent Xe.
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| 4. |
- Karlsmo, Martin, 1995, et al.
(author)
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High‐performant all‐organic aqueous sodium‐ion batteries enabled by PTCDA electrodes and a hybrid Na/Mg electrolyte
- 2021
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In: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:46, s. 24709-24715
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Journal article (peer-reviewed)abstract
- Aqueous sodium-ion batteries (ASIBs) are aspiring candidates for low environmental impact energy storage, especially when using organic electrodes. In this respect, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is a promising anode active material, but it suffers from extensive dissolution in conventional aqueous electrolytes. As a remedy, we here present a novel aqueous electrolyte, which inhibits the PTCDA dissolution and enables their use as all-organic ASIB anodes with high capacity retention and Coulombic efficiencies. Furthermore, the electrolyte is based on two, hence “hybrid”, inexpensive and non-fluorinated Na/Mg-salts, it displays favourable physico-chemical properties and an electrochemical stability window >3 V without resorting to the extreme salt concentrations of water-in-salt electrolytes. Altogether, this paves the way for ASIBs with both relatively high energy densities, inexpensive total cell chemistries, long-term sustainability, and improved safety.
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| 5. |
- Ma, Le Anh, 1992-, et al.
(author)
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Strategies for Mitigating Dissolution of Solid Electrolyte Interphases in Sodium-Ion Batteries
- 2021
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In: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 60:9, s. 4855-4863
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Journal article (peer-reviewed)abstract
- The interfacial reactions in sodium-ion batteries (SIBs) are not well understood yet. The formation of a stable solid electrolyte interphase (SEI) in SIBs is still challenging due to the higher solubility of the SEI components compared to lithium analogues. This study therefore aims to shed light on the dissolution of SEI influenced by the electrolyte chemistry. By conducting electrochemical tests with extended open circuit pauses, and using surface spectroscopy, we determine the extent of self-discharge due to SEI dissolution. Instead of using a conventional separator, beta-alumina was used as sodium-conductive membrane to avoid crosstalk between the working and sodium-metal counter electrode. The relative capacity loss after a pause of 50 hours in the tested electrolyte systems ranges up to 30 %. The solubility of typical inorganic SEI species like NaF and Na2CO3 was determined. The electrolytes were then saturated by those SEI species in order to oppose ageing due to the dissolution of the SEI.
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| 6. |
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| 7. |
- Achenbach, Bastian, et al.
(author)
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Porous Salts Containing Cationic Al24-Hydroxide-Acetate Clusters from Scalable, Green and Aqueous Synthesis Routes
- 2023
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In: Angewandte Chemie International Edition. - 1433-7851 .- 1521-3773. ; 62:29
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Journal article (peer-reviewed)abstract
- The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24(OH)56(CH3COO)12]X4, denoted CAU-55-X, with X=Cl−, Br−, I−, HSO4−. Three-dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24(OH)56(CH3COO)12]Cl4 in water were established resulting in high yields (>95 %, 215 g per batch) within minutes. Specific surface areas and H2O capacities with maximum values of up to 930 m2 g−1 and 430 mg g−1 are observed. The particle size of CAU-55-X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly- and perfluoroalkyl substances (PFAS).
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| 8. |
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| 9. |
- Agarwala, Hemlata, et al.
(author)
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Alternating Metal-Ligand Coordination Improves Electrocatalytic CO2 Reduction by a Mononuclear Ru Catalyst**
- 2023
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 62:17
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Journal article (peer-reviewed)abstract
- Molecular electrocatalysts for CO2-to-CO conversion often operate at large overpotentials, due to the large barrier for C−O bond cleavage. Illustrated with ruthenium polypyridyl catalysts, we herein propose a mechanistic route that involves one metal center that acts as both Lewis base and Lewis acid at different stages of the catalytic cycle, by density functional theory in corroboration with experimental FTIR. The nucleophilic character of the Ru center manifests itself in the initial attack on CO2 to form [Ru-CO2]0, while its electrophilic character allows for the formation of a 5-membered metallacyclic intermediate, [Ru-CO2CO2]0,c, by addition of a second CO2 molecule and intramolecular cyclization. The calculated activation barrier for C−O bond cleavage via the metallacycle is decreased by 34.9 kcal mol−1 as compared to the non-cyclic adduct in the two electron reduced state of complex 1. Such metallacyclic intermediates in electrocatalytic CO2 reduction offer a new design feature that can be implemented consciously in future catalyst designs.
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| 10. |
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