近日，中国科学院化学研究所臧亚萍团队报道了碳纳米环的对称性破坏实现室温三元单分子开关。这一研究成果于2025年10月29日发表在《德国应用化学》杂志上。

单分子电子学为超密集信息处理提供了化学编码途径，但由于热展宽和电子平均，室温操作通常仅限于二元电导状态。

研究组展示了使用室温下的机器人三元开关对称工程碳纳米环。通过破坏对称的1,6键将芘单元嵌入[12]环对苯基主链中，破坏了π段的电子等效性，使前沿轨道局部化。在单分子连接点的受控机械伸长下，分子表现出三个良好分辨的电导板，每个板间隔约一个数量级，提供明确的和可重复的读数。第一性原理输运计算揭示了对称破缺引起的轨道局域化使相干隧道路径离散化，从而解释了观测到的平板通道。这些发现确立了分子对称控制作为室温共轭大环中多态电荷输运的通用设计原则，为高密度单分子逻辑结构开辟了一条途径。

附：英文原文

Title: Symmetry-Breaking in Carbon Nanohoops Enables Room-Temperature Ternary Single-Molecule Switching

Author: Kaili Chang, Qing-Song Deng, Kai Song, Jia-Yin Yang, Chengjia Jing, Bingchen Liu, Xuwei Song, Yuan-Zhi Tan, Daoben Zhu, Yaping Zang

Issue&Volume: 2025-10-29

Abstract: Single-molecule electronics offers chemically encoded routes to ultra-dense information processing, yet room-temperature operation is often limited to binary conductance states due to thermal broadening and electronic averaging. Here we demonstrate robust ternary switching at room temperature using symmetry-engineered carbon nanohoops. Embedding a pyrene unit into the [12]cycloparaphenylene backbone via a symmetry-breaking 1,6-linkage disrupts the electronic equivalence of π–segments and localizes frontier orbitals. Under controlled mechanical elongation in single–molecule junctions, the molecule exhibits three well-resolved conductance plateaus, each separated by ～one order of magnitude, affording unambiguous and reproducible readout. First-principles transport calculations reveal that symmetry-breaking–induced orbital localization discretizes coherent tunneling pathways, accounting for the observed plateaus. These findings establish molecular symmetry control as a general design principle for room-temperature multistate charge transport in conjugated macrocycles, opening a pathway to high-density single-molecule logic architectures.

DOI: 10.1002/anie.202519695

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202519695