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- Mishra, Manish Kumar, et al.
(författare)
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Crystallographic evidence of Watson-Crick connectivity in the base pair of anionic adenine with thymine
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:31, s. 18224-18230
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing an ionic liquid strategy, we report crystal structures of salts of free anionic nucleobases and base pairs previously studied only computationally and in the gas phase. Reaction of tetrabutylammonium ([N-4444](+)) or tetrabutylphosphonium ([P-4444](+)) hydroxide with adenine (HAd) and thymine (HThy) led to hydrated salts of deprotonated adenine, [N-4444][Ad]center dot 2H(2)O, and thymine, [P4444][Thy]center dot 2H(2)O, as well as the double salt cocrystal, [P-4444](2)[Ad][Thy]center dot 3H(2)O center dot 2HThy. The cocrystal includes the anionic [Ad-(HThy)] base pair which is a stable formation in the solid state that has previously not even been suggested. It exhibits Watson-Crick connectivity as found in DNA but which is unusual for the free neutral base pairs. The stability of the observed anionic bases and their supramolecular formations and hydrates has also been examined by electronic structure calculations, contributing to more insight into how base pairs can bind when a proton is removed and highlighting mechanisms of stabilization or chemical transformation in the DNA chains.
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| 2. |
- Tang, Si-Fu, et al.
(författare)
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Forcing Dicyanamide Coordination to f-Elements by Dissolution in Dicyanamide-Based Ionic Liquids
- 2020
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:10, s. 7227-7237
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Tidskriftsartikel (refereegranskat)abstract
- A robust general route to lanthanide dicyanamide (DCA(-)) complexes has been developed where f-element salts are dissolved in DCA(-)-based ionic liquids (ILs) directly or formed in situ, forcing coordination of these normally weakly coordinating soft N-donor anions, even in an ambient, non-moisture-excluding environment. A series of lanthanide complexes [C(2)mim][Ln(DCA)(4)(H2O)(4)] (C(2)mim = 1-ethyl-3-methylimidazolium; Ln = La, Nd, Eu, Tb, Dy, and Yb) and [C(2)mim](3n)[La(OH2)(4) (mu(2)-DCA)(4)](n)[La(OH2)(2)(mu(3)-DCA)(3)(mu(2)-DCA)(4)](2n)(Cl)(4n) were crystallized under a variety of conditions using this methodology and structurally characterized using single crystal X-ray diffraction. Although not all examples were isostructural, the dominant feature across the series was the presence of [Ln(DCA)(4)(H2O)(4)](-) anionic nodes with all terminal DCA(-) ligands accepting hydrogen bonds from the coordinated water molecules forming a 3D metal organic framework. To determine if any structural clues might aid in the further development of the synthetic methodology, the metal-free IL [C(1)mim][DCA] (C(1)mim = 1,3-dimethylimidazolium), a room-temperature solid, crystalline analogue of the reaction IL, which is liquid at room temperature, was also prepared and structurally characterized. The ready isolation of these compounds allowed us to begin an investigation of the physical properties such as the luminescence at room and low temperatures for the Eu, Tb, and Dy representatives.
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