Microstructures of Choline Amino Acid based Biocompatible Ionic Liquids

Abstract

Bio‐compatible ionic liquids (Bio‐ILs) represent a class of solvents with peculiar properties and exhibit huge potential for their applications in different fields of chemistry. Ever since they were discovered, researchers have used bio‐ILs in diverse fields such as biomass dissolution, CO2 sequestration, and biodegradation of pesticides. This review highlights the ongoing research studies focused on elucidating the microscopic structure of bio‐ILs based on cholinium cation ([Ch]+) and amino acid ([AA]−) anions using the state‐of‐the‐art and classical molecular dynamics (MD) simulations. The microscopic structure associated with these green ILs guides their suitability for specific applications. ILs of this class differ in the side chain of the amino acid anions, and varying the side chain significantly affects the structure of these ILs and thus helps in tuning the efficiency of biomass dissolution. This review demonstrates the central role of the side chain on the morphology of choline amino acid ([Ch][AA]) bio‐ILs. The seemingly matured field of bio‐ILs and their employment in various applications still holds significant potential, and the insights on their microscopic structure would steer the field of target specific application of these green ILs.

Reinvigorating aza-Michael reactions under ionic liquid catalysis: a greener approach

“…As a result, the anions greatly dictate the mesoscopic structures of [Cho][AA], as non-polar fragments will segregate from the remaining charged network when interacting with external molecules. 31,32 Other properties of [Cho][AA], viscosity in particular, vary significantly, and, remarkably, some derivatives exhibit lubrication performance comparable to that found for olefin oils. 37…”

“…Further studies and analyses of such cholinium salts, both experimental and theoretical, unveiled their distinctive structural features and capabilities. [30][31][32] Thus, the interaction and dynamics of liquids based on choline and amino acids, as portrayed by [Cho][Ala], suggest a strong H-bond, which, once formed, is persistent, and the proton resides exclusively on the choline hydroxyl. Moreover, no proton transfer occurs within the simulated temporal framework, and there is no evidence of medium-range spatial order.…”

Progress in the applications of biocompatible ionic liquids: renewable commodity production, catalytic and pharmaceutical approaches – a review

“…14,15 Discussions of microscopic structures of naturally occurring cations and anions were published in a recent review article to guide the specific field of application of these green solvents. 16…”

Bulk Nanostructure of Mixtures of Choline Arginate, Choline Lysinate, and Water

“…24,30,31,34 ChAAILs can be functionalized to self-assemble at the nanoscale, like conventional amphiphilic ILs. 21,35 This requires the AA − side chain to contain a sufficiently large apolar group (e.g., alkyl chain or aliphatic ring) 19,29,30,32,35 or an "inert" side chain that does not interact strongly with other constituents like the AA − backbone or cation. 29 Nanostructure can also be induced via the cation 36 or by adding molecular components like glycolipids.…”