Structural Engineering and Optimization of Zwitterionic Salts for Expeditious Discovery of Thermoresponsive Materials

This work reported the discovery of N-triflimide (NTf)-based zwitter-ionic liquids (ZILs) that exhibit UCST-type phase transitions in water, and their further structural optimization in fine-tuning polarity to ultimately afford newfangled thermosensitive materials carrying attractive and biocompatible Tc values that clearly demonstrated the true value of the tunability of ZIL structure. This research established that with non-aromatic, acyclic ZILs as small-molecule thermoresponsive materials, their mixing and de-mixing with water triggered by temperatures are entirely reversible.

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Combinatorial discovery of small-molecule 1,2,3-triazolium ionic liquids exhibiting lower critical solution temperature phase transition

Scientific Reports ◽

10.1038/s41598-020-75392-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Yen-Ho Chu ◽

Mou-Fu Cheng ◽

Yung-Hsin Chiang

Keyword(s):

Phase Transition ◽

Ionic Liquid ◽

Ionic Liquids ◽

Phase Transitions ◽

Small Molecule ◽

Room Temperature ◽

Solution Temperature ◽

Temperature Phase ◽

Critical Solution Temperature ◽

True Value

Abstract Both lower and upper critical solution temperature (LCST and UCST) systems are two typical phase behaviors of thermoresponsive materials with solvents, in which LCST is far less common than UCST. Recent studies on ionic liquids carrying LCST phase transitions have predominantly focused on quaternary ammonium- and phosphonium-based ionic salts. Based on the 1,2,3-triazole core structure assemblable by azide-alkyne cycloaddition click reaction, this work reports the combinatorial synthesis of 1,3,4-trialkylated 1,2,3-triazolium ionic liquids in three libraries with a total of 160 ionic liquids and demonstrates, for the first time, their values in temperature-switchable phase transition with water. In this work, the successful discovery of a new thermoresponsive ionic liquid b26, based on the structure-and-phase separation study of b8 and b9, perfectly exemplified the true value of the tunability of ionic liquid fine structures. For all 160 ionic liquids synthesized, 155 are liquid at room temperature and 22 room-temperature ionic liquids were found to exhibit thermoresponsive phase transitions having low Tc values in water. To the best of our knowledge, this comprehensive study is the first report of small-molecule 1,2,3-triazolium ionic liquids that exhibit LCST property in water.

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Structural fine-tuning of zwitterionic salts for the discovery of LCST-type thermoresponsive materials

Materials Chemistry Frontiers ◽

10.1039/d1qm01018b ◽

2021 ◽

Author(s):

Yen-Ho Chu ◽

Chien-Yuan Chen

Keyword(s):

Ionic Liquids ◽

Phase Transitions ◽

Fine Tuning

We described in this work both the discovery of N-triflimide (NTf)-based zwitterionic ionic liquids (ZILs) that exhibit LCST phase transitions in water and its further structure fine-tuning to afford N-pentafluoroethylsulfonimide...

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