Fig. 2. Timeline showing some of the key milestones and advances in the field from when the concept of porous liquids was first introduced, focusing on the first example of each type of porous liquid and/or use of different porous materials. (d) Reprinted by permission from Springer Nature, Nature Materials, ref. 57. Copyright 2017; (f) reprinted (adapted) with permission from ref. 40. Copyright 2018. American Chemical Society; (g) reprinted by permission from Springer Nature, Nature Chemistry, ref. 53. Copyright 2020; (h) reproduced from ref. 55 with permission from the Royal Society of Chemistry. Copyright 2020; (i) reprinted (adapted) with permission from ref. 56. Copyright 2020. American Chemical Society.