Single-Photon-Induced Electron Spin Polarization of Two Exchange-Coupled Stable Radicals.
J Am Chem Soc
; 144(46): 21005-21009, 2022 Nov 23.
Article
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| MEDLINE
| ID: mdl-36373855
Transient electron paramagnetic resonance spectroscopy has been used to probe photoinduced electron spin polarization of a stable exchange-coupled organic biradical in a Pt(II) complex comprising 4,4'-di-tert-butyl-2,2'-bipyridine (bpy) and 3,6-bis(ethynyl-para-phenyl-nitronyl nitroxide)-o-catecholate (CAT(o-C≡C-Ph-NN)2). Photoexcitation results in four unpaired spins in excited states of this complex, with spins being localized on each of the two radicals, CATâ¢+ and bpyâ¢-. The four spins are all exchange-coupled in these excited states, and an off-diagonal matrix element in the CATâ¢+-NN exchange allows for exchange-enhanced intersystem crossing to the 3T1a state, which possesses (bpyâ¢-)Pt(CATâ¢+) chromophoric triplet character. Fast mixing between this 3T1a state and thermally accessible excited LL'CT state(s) followed by fast relaxation provides spin polarization of the exchange-coupled NN radicals in the 3S0 ground state of the complex. Our results demonstrate that well-defined quantum states of a ground-state biradical can be initialized with single-photon excitation and have the potential for further spin manipulation directed toward quantum information science applications.
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MEDLINE
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En
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J Am Chem Soc
Año:
2022
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Article
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Estados Unidos