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Spin-Polarized Radicals with Extremely Long Spin–Lattice Relaxation Time at Room Temperature in a Metal–Organic Framework

2023; American Chemical Society; Volume: 145; Issue: 50 Linguagem: Inglês

10.1021/jacs.3c09563

1943-2984

Kana Orihashi, Akio Yamauchi, Saiya Fujiwara, Mizue Asada, Toshikazu Nakamura, Joseph Ka‐Ho Hui, Nobuo Kimizuka, Kenichiro Tateishi, Т. Уесака, Nobuhiro Yanai,

Organic and Molecular Conductors Research

The generation of spin polarization is key in quantum information science and dynamic nuclear polarization. Polarized electron spins with long spin–lattice relaxation times (T1) at room temperature are important for these applications but have been difficult to achieve. We report the realization of spin-polarized radicals with extremely long T1 at room temperature in a metal–organic framework (MOF) in which azaacene chromophores are densely integrated. Persistent radicals are generated in the MOF by charge separation after photoexcitation. Spin polarization of a triplet generated by photoexcitation is successfully transferred to the persistent radicals. Pulse electron spin resonance measurements reveal that the T1 of the polarized radical in the MOF is as long as 214 μs with a relatively long spin–spin relaxation time T2 of the radicals of up to 0.98 μs at room temperature. The achievement of extremely long spin polarization in MOFs with nanopores accessible to guest molecules will be an important cornerstone for future highly sensitive quantum sensing and efficient dynamic nuclear polarization.