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Miyokawa K, Kurashige Y. Zero-Field Splitting Tensor of the Triplet Excited States of Aromatic Molecules: A Valence Full-π Complete Active Space Self-Consistent Field Study. J Phys Chem A 2024. [PMID: 38501814 DOI: 10.1021/acs.jpca.4c00466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
A method to predict the D tensor in the molecular frame with multiconfigurational wave functions in large active space was proposed, and the spin properties of the lowest triplets of aromatic molecules were examined with full-π active space; such calculations were challenging because the size of active space grows exponentially with the number of π electrons. In this method, the exponential growth of complexity is resolved by the density matrix renormalization group (DMRG) algorithm. From the D tensor, we can directly determine the direction of the magnetic axes and the ZFS parameters, D- and E-values, of the phenomenological spin Hamiltonian with their signs, which are not usually obtained in ESR experiments. The method using the DMRG-CASSCF wave function can give correct results even when the sign of D- and E-values is sensitive to the accuracy of the prediction of the D tensor and existing methods fail to predict the correct magnetic axes.
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Affiliation(s)
- Katsuki Miyokawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yuki Kurashige
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
- CREST, JST, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
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Sakamoto K, Hamachi T, Miyokawa K, Tateishi K, Uesaka T, Kurashige Y, Yanai N. Polarizing agents beyond pentacene for efficient triplet dynamic nuclear polarization in glass matrices. Proc Natl Acad Sci U S A 2023; 120:e2307926120. [PMID: 37871226 PMCID: PMC10622900 DOI: 10.1073/pnas.2307926120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 09/08/2023] [Indexed: 10/25/2023] Open
Abstract
Triplet dynamic nuclear polarization (triplet-DNP) is a technique that can obtain high nuclear polarization under moderate conditions. However, in order to obtain practically useful polarization, large single crystals doped with a polarizing agent must be strictly oriented with respect to the magnetic field to sharpen the electron spin resonance (ESR) spectra, which is a fatal problem that prevents its application to truly useful biomolecular targets. Instead of this conventional physical approach of controlling crystal orientation, here, we propose a chemical approach, i.e., molecular design of polarizing agents; pentacene molecules, the most typical triplet-DNP polarizing agent, are modified so as to make the triplet electron distribution wider and more isotropic without loss of the triplet polarization. The thiophene-modified pentacene exhibits a sharper and stronger ESR spectrum than the parent pentacene, and state-of-the-art quantum chemical calculations revealed that the direction of the spin polarization is altered by the modification with thiophene moieties and the size of D and E parameters are reduced from parent pentacene due to the partial delocalization of spin densities on the thiophene moieties. The triplet-DNP with the new polarizing agent successfully exceeds the previous highest 1H polarization of glassy materials by a factor of 5. This demonstrates the feasibility of a polarizing agent that can surpass pentacene, the best polarizing agent for more than 30 y since triplet-DNP was first reported, in the unoriented state. This work provides a pathway toward practically useful high nuclear polarization of various biomolecules by triplet-DNP.
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Affiliation(s)
- Keita Sakamoto
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka819-0395, Japan
| | - Tomoyuki Hamachi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka819-0395, Japan
| | - Katsuki Miyokawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto606-8502, Japan
| | - Kenichiro Tateishi
- Cluster for Pioneering Research, RIKEN, RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama351-0198, Japan
| | - Tomohiro Uesaka
- Cluster for Pioneering Research, RIKEN, RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama351-0198, Japan
| | - Yuki Kurashige
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto606-8502, Japan
- Japan Science and Technology Agency-Fusion Oriented REsearch for disruptive Science and Technology, Kawaguchi, Saitama332-0012, Japan
| | - Nobuhiro Yanai
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka819-0395, Japan
- Japan Science and Technology Agency-Fusion Oriented REsearch for disruptive Science and Technology, Kawaguchi, Saitama332-0012, Japan
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Yabuki R, Nishimura K, Hamachi T, Matsumoto N, Yanai N. Generation and Transfer of Triplet Electron Spin Polarization at the Solid-Liquid Interface. J Phys Chem Lett 2023; 14:4754-4759. [PMID: 37184433 DOI: 10.1021/acs.jpclett.3c00627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The photoexcited triplet state of dyes can generate highly polarized electron spins for sensing and dynamic nuclear polarization. However, while triplets exhibit long spin-lattice relaxation times (T1) on the microsecond scale in solids, the polarization quickly relaxes on the nanosecond scale in solution due to the rotational motion of chromophores. Here, we report that the immobilization of dye molecules on a solid surface allows molecular contact with a liquid while maintaining high polarization and long T1 as in a solid. By adsorbing anionic porphyrins on cationic mesoporous silica gel, porphyrin triplets exhibit high polarization and long T1 at the solid-liquid interface of silica and toluene. Furthermore, porphyrin triplets on the solid surface can exchange spin polarization with TEMPO radicals in solution. This simple and versatile method using the solid-liquid interface will open the door for utilizing the photoinduced triplet spin polarization in solution, which has been mainly limited to the solid-state.
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Affiliation(s)
- Reiya Yabuki
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Koki Nishimura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Tomoyuki Hamachi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Naoto Matsumoto
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Nobuhiro Yanai
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
- FOREST, JST, Honcho 4-1-8, Kawaguchi, Saitama 332-0012, Japan
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Nishimura K, Yabuki R, Hamachi T, Kimizuka N, Tateishi K, Uesaka T, Yanai N. Dynamic Electron Polarization Lasting More Than 10 μs by Hybridizing Porphyrin and TEMPO with Flexible Linkers. J Phys Chem B 2023; 127:1219-1228. [PMID: 36717096 DOI: 10.1021/acs.jpcb.2c07936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Dynamic electron polarization (DEP), induced by quenching of photoexcited species by stable radicals, can hyperpolarize electron spins in solution at room temperature. Recently, development of technologies based on electron spin polarization such as dynamic nuclear polarization (DNP) has been progressing, where it is important to design molecules that achieve long-lasting DEP in addition to high DEP. Hybridization by linking dyes and radicals is a promising approach for efficient DEP, but strong interactions between neighboring dyes and radicals often result in the rapid decay of DEP. In this study, we introduce a flexible linker into the hybrid system of porphyrin and TEMPO to achieve both efficient DEP and long-lasting DEP. The structural flexibility of the linker switches the interaction between the radical and the triplet, which promotes the DEP process by bringing the radical and the triplet into close proximity, while avoiding abrupt relaxation due to strong interactions. As a result, the new hybridized system exhibits a larger DEP than the unlinked system, while at the same time achieving a DEP lasting more than 10 μs.
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Affiliation(s)
- Koki Nishimura
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka819-0395, Japan
| | - Reiya Yabuki
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka819-0395, Japan
| | - Tomoyuki Hamachi
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka819-0395, Japan
| | - Nobuo Kimizuka
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka819-0395, Japan
| | - Kenichiro Tateishi
- Cluster for Pioneering Research, RIKEN, RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama351-0198, Japan
| | - Tomohiro Uesaka
- Cluster for Pioneering Research, RIKEN, RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama351-0198, Japan
| | - Nobuhiro Yanai
- Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka819-0395, Japan
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Sannikova NE, Zhdanova KA, Spitsyna AS, Bragina NA, Fedin MV, Krumkacheva OA. Study of Cationic Porphyrins and Their Metal Complexes by ESR Techniques. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s1070328422010031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Fujiwara S, Matsumoto N, Nishimura K, Kimizuka N, Tateishi K, Uesaka T, Yanai N. Triplet Dynamic Nuclear Polarization of Guest Molecules through Induced Fit in a Flexible Metal–Organic Framework**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Saiya Fujiwara
- Department of Applied Chemistry Graduate School of Engineering Center for Molecular Systems (CMS) Kyushu University 744 Moto-oka Nishi-ku, Fukuoka 819-0395 Japan
| | - Naoto Matsumoto
- Department of Applied Chemistry Graduate School of Engineering Center for Molecular Systems (CMS) Kyushu University 744 Moto-oka Nishi-ku, Fukuoka 819-0395 Japan
| | - Koki Nishimura
- Department of Applied Chemistry Graduate School of Engineering Center for Molecular Systems (CMS) Kyushu University 744 Moto-oka Nishi-ku, Fukuoka 819-0395 Japan
| | - Nobuo Kimizuka
- Department of Applied Chemistry Graduate School of Engineering Center for Molecular Systems (CMS) Kyushu University 744 Moto-oka Nishi-ku, Fukuoka 819-0395 Japan
| | - Kenichiro Tateishi
- Cluster for Pioneering Research RIKEN RIKEN Nishina Center for Accelerator-Based Science Wako, Saitama 351-0198 Japan
| | - Tomohiro Uesaka
- Cluster for Pioneering Research RIKEN RIKEN Nishina Center for Accelerator-Based Science Wako, Saitama 351-0198 Japan
| | - Nobuhiro Yanai
- Department of Applied Chemistry Graduate School of Engineering Center for Molecular Systems (CMS) Kyushu University 744 Moto-oka Nishi-ku, Fukuoka 819-0395 Japan
- PRESTO JST Honcho 4-1-8 Kawaguchi, Saitama 332-0012 Japan
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Fujiwara S, Matsumoto N, Nishimura K, Kimizuka N, Tateishi K, Uesaka T, Yanai N. Triplet Dynamic Nuclear Polarization of Guest Molecules through Induced Fit in a Flexible Metal-Organic Framework. Angew Chem Int Ed Engl 2021; 61:e202115792. [PMID: 34935275 DOI: 10.1002/anie.202115792] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Indexed: 11/12/2022]
Abstract
Dynamic nuclear polarization utilizing photoexcited triplet electrons (triplet-DNP) has great potential for room-temperature hyperpolarization of nuclear spins. However, the polarization transfer to molecules of interest remains a challenge due to the fast spin relaxation and weak interaction with target molecules at room temperature in conventional host materials. Here, we demonstrate the first example of DNP of guest molecules in a porous material at around room temperature by utilizing the induced-fit-type structural transformation of a crystalline yet flexible metal-organic framework (MOF). In contrast to the usual hosts, 1 H spin-lattice relaxation time becomes longer by accommodating a pharmaceutical model target 5-fluorouracil as the flexible MOF changes its structure upon guest accommodation to maximize the host-guest interactions. Combined with triplet-DNP and cross-polarization (CP), this system realizes an enhanced 19 F-NMR signal of guest target molecules.
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Affiliation(s)
- Saiya Fujiwara
- Kyushu University: Kyushu Daigaku, Department of Applied Chemistry, JAPAN
| | - Naoto Matsumoto
- Kyushu University: Kyushu Daigaku, Department of Applied Chemistry, JAPAN
| | - Koki Nishimura
- Kyushu University: Kyushu Daigaku, Department of Applied Chemistry, JAPAN
| | - Nobuo Kimizuka
- Kyushu University: Kyushu Daigaku, Department of Applied Chemistry, JAPAN
| | | | - Tomohiro Uesaka
- RIKEN: Rikagaku Kenkyujo, Cluster for Pioneering Research, JAPAN
| | - Nobuhiro Yanai
- Kyushu University, Department of Chemistry and Biochemistry, 744 Moto-oka, Nishi-ku, 819-0395, Fukuoka, JAPAN
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