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Free-Standing Halogen-Bonded Nanosheets Formed by Ultrasonic Liquid Exfoliation
Prioti Choudhury Purba1, Elisa Marelli2, Thomas M Roseveare1
1School of Mathematical and Physical Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|October 29, 2025
Summary
Researchers have created novel free-standing nanosheets using halogen bonding, a type of supramolecular interaction, challenging previous requirements for 2D material exfoliation. These stable, layered materials demonstrate a new class of functional nanomaterials.
Area of Science:
- Materials Science
- Supramolecular Chemistry
- Nanotechnology
Background:
- Layered materials typically require strong in-layer interactions for exfoliation into nanosheets.
- Conventional understanding necessitates robust bonding for creating 2D materials.
Purpose of the Study:
- To report the first formation of free-standing nanosheets stabilized by halogen bonding interactions.
- To investigate the exfoliation and stability of these novel supramolecularly-bonded nanosheets.
Main Methods:
- Synthesis of layered co-crystals using iodo- or bromo-functionalized halogen bond donors and pyridyl acceptors.
- Exfoliation via sonication in polar organic solvents and water.
- Characterization using atomic force microscopy (AFM) and powder X-ray diffraction (PXRD).
Main Results:
- Successful formation of micron-sized nanosheets with near-monolayer thickness.
- Stable aqueous suspensions of iodo-nanosheets exhibiting Tyndall scattering.
- PXRD confirmed a structure with one-dimensional halogen-bonded chains and π-π stacking.
- Iodo-nanosheets demonstrated high stability in acidic/alkaline conditions and thermal stress.
Conclusions:
- Halogen bonding alone can stabilize free-standing nanosheets, challenging established exfoliation criteria.
- The stability difference between iodo- and bromo-analogues suggests stronger halogen bonds enhance material robustness.
- Halogen-bonded nanosheets represent a new class of 2D materials with significant potential.
