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Close-Shell and Biradical Enantiomers for Probing the Chiral-Induced Spin Selectivity Effect
Alexandre Mamontov1, Daniel Goldberg2, Gaël De Leener3
1Laboratoire de Chimie des Polymères, Faculté des Sciences, Université libre de Bruxelles (ULB), Boulevard du Triomphe, CP 206/01, 1050 Brussels, Belgium.
The Journal of Physical Chemistry Letters
|May 12, 2026
Summary
Researchers studied chiral molecules with and without unpaired electrons to understand their effect on chiroptical properties and chiral-induced spin selectivity (CISS). Biradical enantiomers exhibited a magnified CISS effect, offering new insights into spin selectivity in chiral systems.
Area of Science:
- Organic Chemistry
- Physical Chemistry
- Materials Science
Background:
- Chiral molecules exhibit unique interactions with polarized light and spin-polarized electrons.
- The chiral-induced spin selectivity (CISS) effect describes the spin polarization generated by chiral materials.
- Understanding the influence of electronic structure on chiroptical properties and CISS is crucial for developing novel spintronic devices.
Purpose of the Study:
- To investigate the impact of open-shell (biradical) versus close-shell electronic structures on chiroptical properties.
- To quantify the role of unpaired electrons in the chiral-induced spin selectivity (CISS) effect.
- To compare the CISS effect in solution and thin-film states for different electronic structures.
Main Methods:
- Design and synthesis of two pairs of enantiomers with varying electronic structures (close-shell vs. biradical).
- Characterization of enantiomeric purity using techniques ensuring >99% enantiomeric excess.
- Measurement of circular dichroism in solution and thin films.
- Measurement of the chiral-induced anomalous Hall effect.
Main Results:
- Synthesized enantiomers with high purity (>99% enantiomeric excess).
- Observed comparable chiroptical properties between close-shell and biradical enantiomers in solution and films.
- Demonstrated a significantly magnified CISS effect in biradical enantiomers compared to close-shell counterparts in both spectroscopic and electric measurements.
Conclusions:
- The presence of unpaired electrons (open-shell structure) in chiral molecules magnifies the chiral-induced spin selectivity (CISS) effect.
- Electronic structure plays a critical role in modulating chiroptical properties and spin selectivity.
- These findings provide fundamental insights into the interplay between molecular structure, electronic configuration, and spin-dependent phenomena in chiral systems.
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