A Switchable Deep Eutectic System Based on Diarylethene.

Deep eutectic solvents (DESs) have emerged as promising alternative solvents for a wide range of applications, such as extraction and separation processes. To broaden their functionality, the development of responsive DESs (RDESs) has attracted particular interest due to their ability to abruptly change their properties in response to external stimuli. Herein, we aim to prepare a new RDES comprising a photo- and electrochromic dicarboxylic diarylethene derivative (DTE) and quadrol (Q). The prepared system exhibits a color change from yellowish to pinkish-red under UV irradiation due to the photoisomerization of DTE, which can be reverted by visible light or oxidative electrolysis. Interestingly, this process also alters the strength of the hydrogen bonds between DTE and Q, leading to an externally controlled change in the thermal and electrical properties of the eutectic mixture. Therefore, these results demonstrate the capacity to photo- and electromodulate the behavior of DESs by incorporating stimuli-responsive units, thereby opening new perspectives toward the design of solvents with tunable properties for a variety of industrial and materials science applications.