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首页> 外文期刊>RSC Advances >Reorientation dynamics and ion diffusivity of neat dimethylimidazolium dimethylphosphate probed by NMR spectroscopy
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Reorientation dynamics and ion diffusivity of neat dimethylimidazolium dimethylphosphate probed by NMR spectroscopy

机译：NMR光谱法探测整个二甲基咪唑铵的重新定位动力学和离子扩散性

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NMR spectroscopy at two magnetic field strengths was employed to investigate the dynamics of dimethylimidazolium dimethylphosphate ([C1C1IM][(CH3)(2)PO4]). [C1C1IM][(CH3)(2)PO4] is a low-melting, halogen-free ionic liquid comprising of only methyl groups. C-13 spin-lattice relaxation rates as well as self-diffusion coefficients were measured for [C1C1IM][(CH3)(2)PO4] as a function of temperature. The rotational correlation times, tau(c), for the cation and the anion were obtained from the C-13 spin-lattice relaxation rates. Although from a theoretical point of view cations and anions are similar in size, they show different reorientation mobilities and diffusivities. The self-diffusion coefficients and the rotational correlation times were related to the radii of the diffusing spheres. The analysis reveals that the radii of the cation and the anion, respectively, are different from each other but constant at temperatures ranging from 293 to 353 K. The experimental results are rationalised by a discrete and individual cation and anion diffusion. The [(CH3)(2)PO4](-) anion reorients faster compared to the cation but diffuses significantly slower indicating the formation of anionic aggregates. Relaxation data were acquired with standard liquid and magic-angle-spinning NMR probes to estimate residual dipolar interactions, chemical shift anisotropy or differences in magnetic susceptibility within the sample.
机译：使用两个磁场强度的NMR光谱法研究二甲基咪唑鎓二甲基磷酸的动态（[C1C1IM] [（CH 3）（2）PO4]）。 [C1C1IM] [（CH 3）（2）PO4]是一种低熔点，不含卤素离子液体，仅包含甲基。作为温度的函数，测量C-13旋转晶格弛豫速率以及自扩散系数[C1C1IM] [（CH3）（2）PO4]。从C-13旋转晶格松弛率获得阳离子和阴离子的旋转相关时间Tau（C）。虽然从理论的角度和阴离子的大小相似，但它们显示了不同的重新定向迁移率和扩散性。自扩散系数和旋转相关时间与漫射球的半径有关。该分析表明，阳离子和阴离子的半径分别彼此不同，但在293至353k的温度下恒定。实验结果通过离散和单独的阳离子和阴离子扩散来合理化。 [（CH3）（2）PO4]（ - ）阴离子重新定位与阳离子相比快速，但扩散显着表明形成阴离子聚集体的形成。用标准液体和魔法角旋转NMR探针获得弛豫数据，以估计样品内的残留偶极相互作用，化学变换各向异性或磁性敏感性的差异。

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    《RSC Advances》 |2019年第61期|共16页
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  • 正文语种 eng
  • 中图分类 化学;
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