Aluminum ions speciation and transport in acidic deep eutectic AlCl3 amide electrolytes
Aluminum ions speciation and transport in acidic deep eutectic AlCl3 amide electrolytes
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DOI：
10.1016/j.molliq.2020.114118
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发表时间：
2020-12-01
影响因子：
6
通讯作者：
Suarez, Sophia
中科院分区：
文献类型：
--
作者：
Paterno, Domenec;Rock, Emma;Suarez, Sophia
采用变温多核（H-1和Al-27）磁共振和电化学阻抗谱研究了AlCl 3：酰胺深共熔溶剂（DES）中铝离子的形态。重点是对物种运输的本地和散装相互作用之间的相互作用，和AlCl 3浓度对它们的动态的影响。选择乙酰胺、丁酰胺和丙酰胺，并研究AlCl 3：酰胺的摩尔比为1：1-1.7：1。计算的瓦尔登产品表明，尽管DES电解质是“亚离子”，但它们比“差离子液体”更导电。离子电导率数据显示VFT温度依赖性，计算的脆性值小于5的所有三个酰胺和浓度，表明高水平的构象迁移率的铝物种。H-1的化学位移数据显示，增加屏蔽与所有三个酰胺的摩尔比，表明在本地电子密度的增强，可能是由于在更屏蔽的顺式构象人口的增加。Al-27光谱显示，随着AlCl 3浓度的增加，经历了中间和快速化学交换的多种铝物种。AlCl_2（amide）（2）（+）物种数随温度和AlCl_3浓度的增加而减少，尤其是对于较短烷基链的酰胺。这表明在较高的AlCl 3浓度下，它在铝离子迁移中起的作用不太显著。各种物质的Al-27 T-1值显示，对于大于1：1的摩尔比，AlCl 2（酰胺）（+）物质的T-1具有温度和浓度依赖性的平台。此外，随着AlCl 3浓度的增加，AlCl 4和AlCl 2（酰胺）（+）物质的合并导致其T-1最短并且随着温度的增加而增加，这表明其与其他铝物质相比经历更大的电场梯度。(C)2020爱思唯尔B. V.保留所有权利。
Aluminum ion speciation in AlCl3:amide deep eutectic solvents (DES) were explored using variable temperature multi-Nuclear (H-1 and Al-27) Magnetic Resonance and Electrochemical Impedance Spectroscopies. Focus was on the interplay between the local and bulk interactions on species transport, and the effect of AlCl3 concentration on their dynamics. Acetamide, butyrarnide and propionamide were chosen and molar ratios of 1:1-1.7:1 of AlCl3 :amide were studied. Calculated Walden products show that although the DES electrolytes are 'subionic,' they are more conductive than 'poor ILs'. The ionic conductivity data showed VFT temperature dependences, and calculated fragility values were less than 5 for all three amides and concentrations, indicating high levels of conformational mobility for the aluminum species. H-1 chemical shift data showed increased shielding with increasing molar ratios for all three amides indicating an enhancement in the local electron densities, possibly due to an increase in the more shielded cis conformation population. Al-27 spectra revealed multiple aluminum species that experienced both intermediate and fast chemical exchanges with increasing AlCl3 concentration. The AlCl2 (amide)(2)(+) species population decreased with both increasing temperature and AlCl3 concentration, especially for shorter alkyl chains amides. This suggests it plays a less significant role in the aluminum ion transport at higher AlCl3 concentration. Al-27 T-1 values for the various species revealed a temperature and concentration dependent plateauing in the T-1 of the AlCl2 (amide)(+) species for molar ratios greater than 1:1. Additionally, with increasing AlCl3 concentration, the merging of the AlCl4 and AlCl2 (amide)(+) species resulted in its T-1 being the shortest and increasing with increasing temperatures, suggesting it experiences greater electric field gradients compared to the other aluminum species. (C) 2020 Elsevier B.V. All rights reserved.