We have demonstrated a modified crystallization process of an ionic liquid crystal, 1-{[4′-(4″-nitrophenylazo)phenyloxy]}hexyl-3-methyl-1H-imidazol-3-ium tetrafluoroborate, by the addition of carbon nanotubes (CNTs), successfully suppressing the supercooled state, and hence the cold crystallization during reheating, to the complete conversion of melt crystallization upon cooling. The enthalpies of fusion of the crystals produced were similar among the samples (29.3–32.2 kJ mol^–1); however, a crystallization-promoting pathway that increases the crystallization enthalpy by 20% was present. Through comprehensive thermal analysis, structural analysis, and infrared spectroscopy combined with quantum chemical calculations, we propose that this effect is caused by an increased crystal nucleation rate due to the π–π interactions between the molecule and the rigid CNT surface. These results not only give insights into the crystallization processes of ionic liquids in general but also provide guidelines to expand the range of applications of cold-crystallizing ionic crystalline materials for thermal energy storage applications.

中文翻译：

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离子液晶冷结晶过程的分子结构研究

我们已经通过添加碳证明了离子液晶 1-{[4'-(4″-nitrophenylazo)phenyloxy]}hexyl-3-methyl-1 H -imidazol-3-ium tetrafluoroborate的改进结晶过程纳米管（CNTs），成功地抑制了过冷状态，从而抑制了再加热过程中的冷结晶，从而在冷却时完全转化为熔体结晶。所产生的晶体的熔化焓在样品中相似（29.3–32.2 kJ mol ^–1); 然而，存在将结晶焓增加 20% 的结晶促进途径。通过综合热分析、结构分析和红外光谱结合量子化学计算，我们提出这种效应是由于分子与刚性 CNT 表面之间的 π-π 相互作用导致晶体成核率增加所致。这些结果不仅为一般离子液体的结晶过程提供了见解，而且为扩大冷结晶离子晶体材料在热能存储应用中的应用范围提供了指导。