离子液体1-仲丁基-3-甲基咪唑六氟磷酸盐的微波辅助合成、晶体结构及热稳定性

高等学校化学学报 ›› 2009, Vol. 30 ›› Issue (9): 1814.

离子液体1-仲丁基-3-甲基咪唑六氟磷酸盐的微波辅助合成、晶体结构及热稳定性

赵亚梅, 胡小玲, 管萍, 李大鹏

西北工业大学理学院应用化学系, 西安 710072

收稿日期:2008-10-13 出版日期:2009-09-10 发布日期:2009-09-10
通讯作者: 胡小玲, 女, 博士, 教授, 主要从事离子液体和高分子材料等方面的研究. E-mail: huxl@nwpu.edu.cn
基金资助:
国家自然科学基金(批准号： 50572089)资助.

Microwave-Assisted Synthesis, Crystal Structure and Thermal Stability of Ionic Liquid 1-sec-Butyl-3-methylimidazolium Hexfluorophosphate

ZHAO Ya-Mei, HU Xiao-Ling^*, GUAN Ping, LI Da-Peng

Department of Applied Chemistry, School of Natural and Applied Sciences, Northwestern Polytechnical University, Xi′an 710072, China

Received:2008-10-13 Online:2009-09-10 Published:2009-09-10
Contact: HU Xiao-Ling. E-mail: huxl@nwpu.edu.cn
Supported by:
国家自然科学基金(批准号： 50572089)资助.

摘要/Abstract

摘要：

以具有支链结构的溴代仲丁烷作为烷基化试剂, 在微波辐射下采用两步法合成了1-仲丁基-3-甲基咪唑六氟磷酸盐([s-bmim][PF₆])离子液体. 在配比为V(水)∶V(乙醇)∶V(甲苯)=0.16∶2.84∶7的混合溶剂体系中, 培养出晶型完整的长约11 mm的离子液体大单晶体. 通过单晶体X衍射研究了[s-bmim][PF₆]的晶体结构. [s-bmim][PF₆]属于三斜立方晶系, 空间群为P2(1)/m, 晶胞参数为a=0.9042(4) nm, b=0.8213(3) nm, c=0.9775(4) nm, γ=116.618°(6), Z=2, V=64.909(4) nm³, D_c=1.454 g/cm³, μ=0.265 mm^-1, F(000)=292. 在[s-bmim][PF₆]晶体结构中, 阴阳离子间的离子键仍然是主要的, 同时还存在氢键和阳离子-阳离子间的非键斥力作用. 研究结果表明, [s-bmim][PF₆]的支化烷基结构对其晶体有效堆积、熔点、液程范围以及热分解温度等性质具有重要影响.

关键词: 离子液体; 微波合成; 晶体结构; 热稳定性

Abstract:

In this paper, 1-sec-butyl-3-methylimidazolium hexfluorophosphate([s-bmim][PF₆]) was synthesized with the aid of microwave. Large single crystals were formed in the water-ethanol-toluene system[V(water)∶V(ethanol)∶V(toluene)=0.16∶2.84∶7]. The large single crystals are stable under the air and moisture, with the maximum length of 11 mm. The crystal structure was determined by X-ray diffraction. [s-bmim][PF₆] crystallizes in the monoclinic space group P2₁/m, with unit-cell parameters a=0.9042(4) nm, b=0.8213(3) nm, c=0.9775(4) nm, γ=116.618°(6), Z=2, V=64.909(4) nm³, D_c=1.454 g/cm³, μ=0.265 mm^-1, F(000)=292, the final R=0.0998, wR=0.2656. In the structure, the cations and anions can not form neutral ion pairs owing to the interionic interactions such as the dominant Coulombic attraction, the weak hydrogen bonds and the non-chemical-bond tension of cation-cation. Moreover, it was found that introducing the sec-butyl chain could change the asymmetry of cations and inhibit the rotation of the alky chains of [s-bmim][PF₆]. The branched structure leads to the void space filling in the crystal stacking and high lattice energy. Finally, the thermal stability of [s-bmim][PF₆] was discussed.

Key words: Ionic liquid; Microwave synthesis; Crystal structure; Thermal stability

TrendMD:

赵亚梅, 胡小玲, 管萍, 李大鹏. 离子液体1-仲丁基-3-甲基咪唑六氟磷酸盐的微波辅助合成、晶体结构及热稳定性. 高等学校化学学报, 2009, 30(9): 1814.

ZHAO Ya-Mei, HU Xiao-Ling*, GUAN Ping, LI Da-Peng. Microwave-Assisted Synthesis, Crystal Structure and Thermal Stability of Ionic Liquid 1-sec-Butyl-3-methylimidazolium Hexfluorophosphate. Chem. J. Chinese Universities, 2009, 30(9): 1814.