同济大学韩海祥团队近日研究了具有对映体偏置结晶的手性CdS幻数尺寸簇。2025年5月15日出版的《美国化学会志》发表了这项成果。

尽管二元半导体纳米晶体中通常存在对称的非手性原子晶格，但研究组发现，在其早期形成阶段，特别是在幻数尺寸簇（MSC）体系中，手性可以存在于这些亚稳态、瞬态物种中，它们能够进一步自组装成高级手性超结构。通过在室温下操作的阳离子交换过程，结构对称的硫化铜簇已成功转化为一对对映体硫化镉MSC，其化学式为Cd₂₈S₁₇I₂₂（PEt₃）₁₂（缩写为（+）/（-）-[Cd₂₈S₁₇]）。 

通过单晶X射线晶体学确定了这两种MSC的原子结构。据透露，[Cd₂₈S₁₇]MSC具有反超四面体结构，这在已有的CdS结构中从未被观察到。值得注意的是，（+）/（-）-[Cd₂₈S₁₇]MSCs不是结晶成外消旋混合物，而是以对映体偏置的方式自然结晶出来，充分呈现出明显相反的手性反应。这种行为反映了真正的圆二色性活性，这可以直接归因于这种众所周知的量子光子纳米材料的手性原子结构。

附：英文原文

Title: A Chiral CdS Magic-Size Cluster with Enantiomerically-Biased Crystallization

Author: Cheng Xu, Zhenyi Zhang, Zheng Zhou, Haixiang Han

Issue&Volume: May 15, 2025

Abstract: Despite the symmetric, achiral atomic lattices typically found in binary semiconductor nanocrystals, we show that during their early formation stages, especially in the magic-size cluster (MSC)  regime, chirality can be present in these metastable, transient species, which are capable of  further self-assembling into high-level chiral superstructures. Through a cation exchange process operating at room temperature, a structurally symmetrical copper sulfide cluster has been successfully converted into a pair of enantiomeric cadmium sulfide MSCs, formulated as Cd28S17I22(PEt3)12 (abbreviated as (+)/()-[Cd28S17]). The atomic structures of these two MSCs were established by single-crystal X-ray crystallography. It is revealed that the [Cd28S17] MSCs feature an antisupertetrahedron configuration which has never been observed in reported CdS structures. Remarkably, rather than crystallizing into a racemic mixture,  (+)/()-[Cd28S17] MSCs naturally crystallize out in an enantiomerically biased manner, sufficiently rendering distinctly opposite chiroptical responses. This behavior reflects genuine circular dichroism activity, which can be directly attributed to the chiral atomic structure of this well-known quantum photonic nanomaterial.

DOI: 10.1021/jacs.5c02549

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c02549