Imidazolium-based ionic liquids with different fatty acid anions: phase behavior, electronic structure and ionic conductivity investigationElectronic supplementary information (ESI) available: Synthetic protocol of different ionic liquids and corresponding NMR, CHN analysis and ESI-MS data; DSC thermogram of [DMIM][C13H27-CO2] and IL1, IL3 and IL1b (cooling curve). POM image and XRD pattern of isotropic phase of IL1, optimized geometry, tables corresponding to estimated lengths of different ioni

• Main Authors: Biswas, Mrinmoy, Dule, Madhab, Samanta, Pabitra N, Ghosh, Sharmistha, Mandal, Tarun K
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c4cp01324g

The thermal phase behaviors of a series of newly designed 1-alkyl-3-methylimidazolium ionic liquids (ILs) of different chain length fatty acid carboxylate anions are investigated. The length of the alkyl chain of the carboxylate anion in IL influences the phase transition temperature of their crystalline solid phase and the mesophase stability. When the palmitate anion of the IL is replaced with palmitoyl ascorbate and palmitoyl- l -tryptophanate anions, its melting temperature decreases and eventually vanishes. The influence of structural modulation of ILs on their ionic conductivities is also studied. The interaction between the 1-alkyl-3-methylimidazolium cation and the fatty acid carboxylate anion is established by using ab initio based DFT calculations. The associated energies for single ion pair formation of these ILs are computed and are successfully correlated with the experimental findings, which finally leads to the most reasonable arrangement of the IL molecules in different phases. This manuscript presents phase behavior, ionic conductivity and electronic structure investigation of 1-alkyl-3-methylimidazolium-based ionic liquids containing different chain length fatty acid carboxylate anions.