Zhang Di, Zhu Ziqi, Xiao Xiao, Fang Yu-Hui, Xiao Tongtong, Wang Xiaoge, Jiang Shang-Da, Zhao Dahui
Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China.
Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou 510641, China.
J Am Chem Soc. 2024 Aug 7;146(31):21752-21761. doi: 10.1021/jacs.4c05898. Epub 2024 Jul 26.
Organic polyradicals with a high-spin ground state and quantum magnetic properties suitable for spin manipulation are valuable materials for diverse innovative technologies, including quantum devices. However, the typically high reactivity and low stability of conventional polyradicals present a major obstacle to such applications. In this study, a highly stable carbon-centered triradical with a quartet ground state and excellent stability (τ of ∼90 days in air-saturated toluene at room temperature) is achieved, which shows apposite magnetic anisotropy and Zeeman splitting partition with favorable addressability. By virtue of the optimal stability, thorough structural and magnetic characterizations are realized. With X-ray crystallography unambiguously proving the molecular structure, the quartet ground state (Δ = 0.78 kcal/mol) is confirmed by the SQUID measurements, while the cw- and pulsed EPR techniques offer additional supportive evidence for the high-spin nature. Remarkably, owing to the easily attained magnetic anisotropy, selective excitations between different Zeeman splitting levels are successfully demonstrated with in its frozen toluene solution without the requirement for special alignment, which is unprecedented for organic polyradicals. Along with the millisecond spin-lattice relaxation and microsecond coherence time manifested by , this triradical is promising for potential coherent spin manipulation applications as a multienergy-level quantum information carrier.
具有高自旋基态和适用于自旋操控的量子磁特性的有机多自由基，是包括量子器件在内的多种创新技术的宝贵材料。然而，传统多自由基通常具有的高反应性和低稳定性，对这类应用构成了重大障碍。在本研究中，实现了一种具有四重态基态且稳定性极佳（室温下在空气饱和的甲苯中τ约为90天）的高度稳定的碳中心三自由基，它表现出合适的磁各向异性和具有良好可寻址性的塞曼分裂分布。凭借其最佳稳定性，实现了全面的结构和磁性表征。通过X射线晶体学明确证明了分子结构，通过超导量子干涉仪测量确认了四重态基态（Δ = 0.78千卡/摩尔），而连续波和脉冲电子顺磁共振技术为高自旋性质提供了额外的支持证据。值得注意的是，由于易于实现磁各向异性，在其冷冻甲苯溶液中成功展示了不同塞曼分裂能级之间的选择性激发，无需特殊取向，这对于有机多自由基来说是前所未有的。连同该三自由基表现出的毫秒级自旋 - 晶格弛豫和微秒级相干时间，这种三自由基作为多能级量子信息载体，在潜在的相干自旋操控应用方面很有前景。
