Regulation of quantum spin conversions in a single molecular radical

Caiyao Yang; Zhongxin Chen; Cuiju Yu; Jiawen Cao; Guojun Ke; Weiya Zhu; Weixuan Liang; Jiaxing Huang; Wanqing Cai; Chinmoy Saha; Md Abdus Sabuj; Neeraj Rai; Xingxing Li; Jinlong Yang; Yuan Li; Fei Huang; Xuefeng Guo

doi:10.1038/s41565-024-01632-2

Regulation of quantum spin conversions in a single molecular radical

Nat Nanotechnol. 2024 Mar 6. doi: 10.1038/s41565-024-01632-2. Online ahead of print.

Authors

Caiyao Yang^#^{1

2}, Zhongxin Chen^#³, Cuiju Yu^#⁴, Jiawen Cao¹, Guojun Ke³, Weiya Zhu³, Weixuan Liang³, Jiaxing Huang³, Wanqing Cai³, Chinmoy Saha⁵, Md Abdus Sabuj⁵, Neeraj Rai⁵, Xingxing Li⁶, Jinlong Yang⁴, Yuan Li⁷, Fei Huang⁸, Xuefeng Guo^{9

10}

Affiliations

¹ Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Centre, College of Chemistry and Molecular Engineering, Peking University, Beijing, P. R. China.
² School of Materials Science and Engineering, Peking University, Beijing, P. R. China.
³ Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, P. R. China.
⁴ Department of Chemical Physics, University of Science and Technology of China, Hefei, P. R. China.
⁵ Dave C. Swalm School of Chemical Engineering and Centre for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS, USA.
⁶ Department of Chemical Physics, University of Science and Technology of China, Hefei, P. R. China. lixx@ustc.edu.cn.
⁷ Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, P. R. China. celiy@scut.edu.cn.
⁸ Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, P. R. China. msfhuang@scut.edu.cn.
⁹ Beijing National Laboratory for Molecular Sciences, National Biomedical Imaging Centre, College of Chemistry and Molecular Engineering, Peking University, Beijing, P. R. China. guoxf@pku.edu.cn.
¹⁰ Centre of Single-Molecule Sciences, Institute of Modern Optics, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology, College of Electronic Information and Optical Engineering, Nankai University, Tianjin, P. R. China. guoxf@pku.edu.cn.

^# Contributed equally.

PMID: 38448520
DOI: 10.1038/s41565-024-01632-2

Abstract

Free radicals, generally formed through the cleavage of covalent electron-pair bonds, play an important role in diverse fields ranging from synthetic chemistry to spintronics and nonlinear optics. However, the characterization and regulation of the radical state at a single-molecule level face formidable challenges. Here we present the detection and sophisticated tuning of the open-shell character of individual diradicals with a donor-acceptor structure via a sensitive single-molecule electrical approach. The radical is sandwiched between nanogapped graphene electrodes via covalent amide bonds to construct stable graphene-molecule-graphene single-molecule junctions. We measure the electrical conductance as a function of temperature and track the evolution of the closed-shell and open-shell electronic structures in real time, the open-shell triplet state being stabilized with increasing temperature. Furthermore, we tune the spin states by external stimuli, such as electrical and magnetic fields, and extract thermodynamic and kinetic parameters of the transition between closed-shell and open-shell states. Our findings provide insights into the evolution of single-molecule radicals under external stimuli, which may proof instrumental for the development of functional quantum spin-based molecular devices.

Abstract

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