# A Switchable Deep Eutectic System Based on Diarylethene

## TL;DR

A new switchable deep eutectic solvent changes color and properties in response to light or electricity, offering potential for tunable industrial applications.

## Contribution

The paper introduces a photo- and electro-responsive deep eutectic system based on diarylethene.

## Key findings

- The system changes color from yellowish to pinkish-red under UV light due to photoisomerization.
- Visible light or oxidative electrolysis can revert the color change and alter hydrogen bonding strength.
- The solvent's thermal and electrical properties are externally controllable via stimuli.

## Abstract

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.