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A Chiral CdS Magic-Size Cluster with Enantiomerically-Biased Crystallization
Cheng Xu1, Zhenyi Zhang2, Zheng Zhou1
1Interdisciplinary Materials Research Center, School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
Journal of the American Chemical Society
|May 15, 2025
Summary
Chiral cadmium sulfide magic-size clusters (MSCs) were synthesized via cation exchange. These chiral MSCs self-assemble into chiral superstructures, exhibiting circular dichroism due to their unique atomic structure.
Area of Science:
- Materials Science
- Nanotechnology
- Crystallography
Background:
- Binary semiconductor nanocrystals typically exhibit achiral atomic lattices.
- Metastable, transient species in early formation stages, particularly magic-size clusters (MSCs), can possess chirality.
- These chiral species can self-assemble into higher-order chiral superstructures.
Purpose of the Study:
- To demonstrate the presence of chirality in semiconductor nanocrystals during their formation.
- To synthesize and characterize chiral cadmium sulfide MSCs.
- To investigate the self-assembly of chiral MSCs into chiral superstructures.
Main Methods:
- Cation exchange process at room temperature.
- Single-crystal X-ray crystallography for atomic structure determination.
- Chiroptical response measurements.
Main Results:
- A symmetrical copper sulfide cluster was converted into enantiomeric cadmium sulfide MSCs, (+)/(-)-[Cd28S17].
- The [Cd28S17] MSCs possess a novel antisupertetrahedron configuration.
- The MSCs crystallized in an enantiomerically biased manner, not as a racemic mixture.
- Distinctly opposite chiroptical responses were observed, indicating genuine circular dichroism activity.
Conclusions:
- Chirality can emerge in binary semiconductor nanocrystals during formation, specifically in the MSC regime.
- The synthesized chiral CdS MSCs self-assemble into chiral superstructures with observable chiroptical properties.
- The observed circular dichroism is directly linked to the unique chiral atomic structure of the CdS MSCs.
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