Crystal Structure and Properties of Imidazo‐Pyridine Ionic Liquids

Computational studies were performed on novel protic ionic liquids imidazolium‐[1,2‐a]‐pyridine trifluoroacetate [ImPr][TFA] synthesized by the reaction of imidazo‐[1,2a]‐pyridine (ImPr) with trifluoroacetic acid (TFA), and on fused salt imidazolium‐[1,2‐a]‐pyridine maleamic carbonate [ImPr][Mal] synthesized by reaction of ImPr with maleamic acid (Mal). Synthesis was performed as one‐pot reactions, which applies green chemistry tenets. Both these compounds begin to decompose at 180°C. Our computational studies suggest another thermal reaction channel, in which [ImPr][Mal] can also thermally polymerizes to polyacrylamide which then cyclizes. This is thermal product remains stable up to 700 degrees, consistent with our thermogravimetric studies. [ImPr][TFA] exhibited good conductivity and ideal ionic behavior, as evaluated by a Walden plot. X‐ray crystallography of [ImPr][TFA] revealed a tightly packed system for the crystals as a result of strong ionic interaction, pi‐stacking, and fluorine—CH interactions. Both synthesized compounds exhibited some CO 2 absorptivity, with [ImPr][Mal] outperforming [ImPr][TFA] in this regard. The quantum chemistry based computational methods can shed light on many properties of these ionic liquids, but they are challenged in fully describing their ionic nature. © 2017 Wiley Periodicals, Inc.