Exploring physicochemical aspects of N-alkylimidazolium based ionic liquids

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• 作者：Mohsin Ahmad Bhat^a ; ^{mohsinch@kashmiruniversity.ac.in} ; Chanmeet K. Dutta^b ; Ghulam Mohammad Rather^b
• 关键词：Room temperature ionic liquid (RTIL) ; Surface tension ; Excess surface energy ; Specific conductance ; Cosolvent ; Photoluminescence
• 刊名：Journal of Molecular Liquids
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：181
• 期：Complete
• 页码：142-151
• 全文大小：1273 K

文摘

Physicochemical aspects (structural, thermodynamic and transport) of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BDMIM][BF₄]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) room temperature ionic liquids (RTILs) are reported. The results based on temperature dependence of surface tension, conductivity, photoluminescence and spectroscopic measurements on RTILs and their mixtures with acetonitrile (ACN) as cosolvent are interpreted in-terms of structure-composition-property relations. The presented observations clearly indicate that a highly structured and organized arrangement of constituents prevails in the investigated RTILs, which is sensitive to temperature variations and cosolvent addition. Thermodynamic and structural parameters estimated from temperature dependency of interfacial tension demonstrate that surface characteristics are dominated by covalent interactions in imidazolium based RTILs. From composition dependence of measured parameters in RTIL-cosolvent mixtures it is shown that ACN mixes nonideally with RTIL, and interestingly the investigated RTILs retain their inherent structural order up to high dilution limits (0.3 volume fraction of RTIL), beyond which these behave as associated electrolytes. The presented findings seem useful for arriving at molecular basis of physicochemical aspects and future applications of RTILs and their binary mixtures especially with cosolvents for biphasic catalysis and heterogeneous electron transfer reactions, wherein temperature elevation and cosolvent addition are currently advocated as operationally simple means to speed up the mass transport.