Emergent complexity of quantum rotation tunneling
Yilin Guo, Chen Yang, Xinmiao Xie, Yanwei Li, K. N. Houk, Xuefeng Guo
Abstract
Conformational isomerism determines the performance of materials and the activity of biomolecules. However, a complete dynamic study of conformational isomerization is still a formidable challenge at the single-molecule level. In this work, we present real-time in situ electrical monitoring of the full rotation dynamics of a single aromatic chain covalently embedded in graphene electrodes with single-event resolution. We reveal that the dynamic process of phenyl ring rotations at low temperature is dominated by quantum rotation tunneling rather than the quasi-free rotation process. The emergent complexity of different intramolecular rotations in a single aromatic molecule is demonstrated, including the alternating unidirectional rotation with multi-, single-, and half-circle delays driven by inelastic electron tunneling, which has not been previously adequately considered at the macroscopic level. This work builds a bridge between macroscopic and microscopic worlds and improves our understanding of structure-activity relationships, potentially bringing different functions to ordinary materials.