Synthesis, Toxicity, and Biodegradation of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

TAAILs (Tunable Aryl Alkyl Ionic Liquids) are a new class of ionic liquids with an entirely new cationic substructure and a completely different charge distribution. They have a broad potential for applications, e.g., in metal extraction. In compliance with the basic principles of green chemistry, the optimization of the technological properties of chemicals should be investigated in parallel with the minimization of their (eco)toxicological hazard potential. In this study, we therefore synthesized and assessed the environmental effects of seven congeneric cations with different substitution patterns. In vitro assays with the isolated enzyme acetylcholinesterase and the cytotoxicity assay with IPC-81 cells were used, in conjunction with two in vivo tests using the marine bacteria Vibrio fischeri and the limnic green algae Scenedesmus vacuolatus, to assess the biological activity of these ionic liquids. Their biodegradability was tested using available procedures. Throughout this manuscript, special emphasis will be placed on the question of whether biological effects observed for TAAILs are hydrophobicity based (as was found for many common ILs) or whether the unique electronic structure of TAAILs changes the toxicity and/or the biodegradability in comparison with standard ionic liquid structures.