A Quenchofluorometric Investigation Reveals New Insights into Lithium Salt-Based Deep Eutectic Solvents

Area of Science:

• Electrochemistry
• Physical Chemistry
• Materials Science

Background:

• Deep eutectic solvents (DESs) are gaining attention for electrochemical applications.
• Lithium salt-based DESs are particularly promising due to their unique properties.
• Understanding their solvation behavior is crucial for optimizing their use.

Purpose of the Study:

• To investigate the solvation characteristics of lithium salt-based DESs.
• To explore the influence of H-bond donor and composition on DES properties.
• To compare the behavior of lithium DESs with other solvent systems.

Main Methods:

• Utilizing fluorescence spectroscopy with pyrene as a probe.
• Employing nitromethane for fluorescence quenching studies.
• Analyzing temperature-dependent fluorescence data (288-348 K).

Main Results:

• Cybotactic region dipolarity varies among LiTf2N-based DESs, with urea showing the highest.
• Increasing acetamide content decreases the dipolarity of LiTf2N/acetamide DES.
• LiTf2N DESs exhibit lower dipolarity than choline chloride DESs and ionic liquids.
• Fluorescence quenching data reveal anomalous solute-solvent interactions, distinct from other media.

Conclusions:

• Lithium bis(trifluoromethylsulfonyl)imide (LiTf2N)-based DESs possess distinct solvation characteristics.
• These DESs display unique interactions with solutes, differing from conventional solvents and ionic liquids.
• The findings suggest potential for novel applications leveraging these anomalous interactions.