Chongqing Key Laboratory of Inorganic Special Functional Materials, College of Chemistry and Chemical Engineering, Yangtze Normal University, Chongqing 408100, China.
Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States.
J Am Chem Soc. 2020 Jun 10;142(23):10314-10318. doi: 10.1021/jacs.0c04160. Epub 2020 May 26.
Fluorides have been widely applied in pharmaceutical, medicinal, and materials science as well as in fine chemical manufacturing. The performance of fluorides, however, can be markedly affected by the water content. One previous study (Maiti, A.; et al. 2008, 10, 5050) suggested that anhydrous 1,3-dimethylimidazolium fluoride ([DMIm]F) was unstable since the fluoride undergoes a self-decomposition reaction. Herein we first show quantum-chemical calculation evidence that although gas-phase [DMIm]F is unstable, the bulk phase of anhydrous [DMIm]F is quite stable. We then demonstrate the successful synthesis of the anhydrous [DMIm]F compound via the reaction between 1,3-dimethylimidazolium iodide and silver fluoride. Importantly, we find that anhydrous [DMIm]F possesses a high dissolution capability toward 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), although it is known that TATB is hardly dissolved in many common organic solvents. Our Born-Oppenheimer molecular dynamics (BOMD) simulations further show that the high dissolving ability of anhydrous [DMIm]F toward TATB can be attributed to the chemical reaction between the F anion and the TATB molecules, which disrupts the strong hydrogen-bonding interaction among the TATB molecules. Alternatively, water molecules in hydrous [DMIm]F tend to form a hydration layer around the F anion, thereby preventing F from reacting with the TATB molecule. This result explains why TATB is barely dissolved in hydrous [DMIm]F.
氟化物在医药、材料科学以及精细化工制造等领域得到了广泛的应用。然而，氟化物的性能会受到含水量的显著影响。先前的一项研究（Maiti，A.等人，2008 年，10 卷，5050 页）表明无水 1,3-二甲基咪唑氟化物([DMIm]F)是不稳定的，因为氟化物会发生自分解反应。在此，我们首次通过量子化学计算证明，尽管气相[DMIm]F 是不稳定的，但无水[DMIm]F 的体相是相当稳定的。然后，我们通过 1,3-二甲基咪唑碘化物和氟化银之间的反应证明了无水[DMIm]F 化合物的成功合成。重要的是，我们发现无水[DMIm]F 对 1,3,5-三氨基-2,4,6-三硝基苯（TATB）具有很高的溶解能力，尽管众所周知 TATB 很难溶解在许多常见的有机溶剂中。我们的 Born-Oppenheimer 分子动力学（BOMD）模拟进一步表明，无水[DMIm]F 对 TATB 的高溶解能力归因于 F 阴离子和 TATB 分子之间的化学反应，这破坏了 TATB 分子之间强氢键相互作用。相反，水合[DMIm]F 中的水分子倾向于在 F 阴离子周围形成一个水化层，从而阻止 F 与 TATB 分子反应。这一结果解释了为什么 TATB 在水合[DMIm]F 中几乎不溶解。
