Isomerism reflects the ubiquitous nature that molecules with the same molecular formula show different structures. The interconversion between conformational isomers of flexible molecules is quite fast owing to the low barriers of around 10 kcal mol⁻¹, leading to average signal contributed by all the possible isomers characterized by ensemble methods. On this account, identifying the conformational isomers of flexible molecules at room temperature has a substantial challenge. Here, we develop a single-molecule approach to identify the conformational isomers of cyclohexane at room temperature through the single-molecule electrical characterization. By noise analysis and feature extraction of the conductance of single-molecule junctions, we quantificationally identified two chair isomers of cyclohexane at room temperature, while such identification is only feasible at low temperatures by ensemble characterization. The strategy to apply the single-molecule approach to identify conformational isomers paves the avenue to investigate the isomerization of flexible molecules beyond the ensemble methods.

异构反映了具有相同分子式的分子显示不同结构的普遍性。由于约10 kcal mol ^-1的低势垒，柔性分子的构象异构体之间的相互转化非常快，导致以集合方法为特征的所有可能异构体贡献的平均信号。因此，在室温下鉴定柔性分子的构象异构体具有很大的挑战。在这里，我们开发了一种单分子方法，通过单分子电特征鉴定室温下环己烷的构象异构体。通过噪声分析和单分子连接电导的特征提取，我们定量地鉴定了室温下环己烷的两个椅子异构体，而这种鉴定仅在低温下通过整体表征是可行的。