Pentaglyme-K Salt Binary Mixtures: Phase Behavior, Solvate Structures, and Physicochemical Properties
Pentaglyme-K Salt Binary Mixtures: Phase Behavior, Solvate Structures, and Physicochemical Properties
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五甘醇二甲醚-钾盐二元混合物：相行为、溶剂化物结构和理化性质
DOI：
10.1039/c4cp05017g
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发表时间：
2015
影响因子：
3.3
通讯作者：
and Masayoshi Watanabe
中科院分区：
文献类型：
--
作者：
Toshihiko Mandai;Seiji Tsuzuki;Kazuhide Ueno;Kaoru Dokko;and Masayoshi Watanabe
我们制备了一系列由某些钾盐 (KX) 和五甘醇二甲醚 (G5) 组成的具有不同盐浓度和阴离子种类的二元混合物 ([X]−: [(CF3SO2)2N]− = [TFSA]−, [CF3SO3]− = [TfO]−, [C4F9SO3]− = [NfO]−, PF6−, SCN−)，并根据相图、溶剂化物结构和物理化学性质对它们进行了表征。它们的相图和热稳定性强烈暗示等摩尔配合物的形成。对某些等摩尔配合物进行单晶 X 射线晶体学分析，结果表明 G5 分子以特有的方式与 K+ 阳离子配位，就像结晶状态下的 18-冠-6 醚一样，与配对的阴离子无关。通过温度依赖性拉曼光谱和 X 射线晶体学的结合阐明了熔融状态下的溶剂化物结构。在 [K(G5)1][TfO] 拉曼光谱中观察到剧烈的光谱变化，表明结晶态的溶剂化结构在熔化时破裂。 [K(G5)1]X 的溶剂化稳定性与母盐的离子-离子相互作用密切相关。当 K+ 和 G5 之间的离子-偶极相互作用压倒 K+ 和 X− 之间的离子-离子相互作用时，就会形成稳定的溶剂化物。此外，还评估了某些等摩尔混合物的物理化学性质。瓦尔登图清楚地反映了熔融等摩尔配合物的离子性质。根据结构特征和离解性，我们将[K(G5)1]X分为两类：良好溶剂化离子液体和不良溶剂化离子液体。
We prepared a series of binary mixtures composed of certain K salts (KX) and pentaglyme (G5) with different salt concentrations and anionic species ([X]−: [(CF3SO2)2N]− = [TFSA]−, [CF3SO3]− = [TfO]−, [C4F9SO3]− = [NfO]−, PF6−, SCN−), and characterized them with respect to their phase diagrams, solvate structures, and physicochemical properties. Their phase diagrams and thermal stability strongly implied the formation of equimolar complexes. Single-crystal X-ray crystallography was performed on certain equimolar complexes, which revealed that G5 molecules coordinate to K+ cations in a characteristic manner, like 18-crown-6 ether in the crystalline state, irrespective of the paired anions. The solvate structures in the molten state were elucidated by a combination of temperature-dependent Raman spectroscopy and X-ray crystallography. A drastic spectral variation was observed in the [K(G5)1][TfO] Raman spectra, indicating that solvate structures in the crystalline state break apart upon melting. The solvate stability of [K(G5)1]X is closely related to the ion–ion interaction of the parent salts. A stable solvate forms when the ion–dipole interaction between K+ and G5 overwhelms the ion–ion interaction between K+ and X−. Furthermore, the physicochemical properties of certain equimolar mixtures were evaluated. A Walden plot clearly reflects the ionic nature of the molten equimolar complexes. Judging from the structural characteristics and dissociativity, we classified [K(G5)1]X into two groups, good and poor solvate ionic liquids.