Abstract: This work reports the 23000- and 9200-fold enhancement of the 15N nuclear spin polarization of cis and trans isomers of azobenzene, correspondingly, as compared to the thermal NMR signals at 9.4 T by exploiting signal amplification by reversible exchange (SABRE) and parahydrogen molecules at 400 nT simultaneously with light irradiation. Only cis-azobenzene gains substantial hyperpolarization of its 15N spins directly from parahydrogen in SABRE through coherent polarization transfer. Consequently cis-trans photoisomerization at ultralow magnetic field preserves the SABRE-derived nuclear hyperpolarization of cis-azobenzene resulting in hyperpolarization of trans-azobenzene as well, despite its direct coordination with the SABRE Ir-complex being sterically hindered. Moreover, the proposed approach, which we called photo-SABRE, allows to hyperpolarize the long-lived spin order of trans-isomer 15N spins with a lifetime of about 25 minutes, which greatly exceeds their relaxation times at high (10 seconds) and low (200 seconds) magnetic field. Since this spin order in 15N2-trans-azobenzene is collectively formed by nuclei of different kinds, it can be detected by both 15N or 1H NMR spectroscopy.

Cite: Kiryutin A.S. , Kozinenko V.P. , Yurkovskaya A.V.
Photo‐SABRE: Nuclear Spin Hyperpolarization of cis‐trans Photoswitchable Molecules by Parahydrogen**
ChemPhotoChem. 2024. V.8. N1. e202300151 . DOI: 10.1002/cptc.202300151 WOS РИНЦ OpenAlex

Dates:

Submitted:	Jul 14, 2023
Accepted:	Oct 11, 2023
Published online:	Oct 11, 2023

Identifiers:

Web of science:	WOS:001123483900001
Elibrary:	64183251
OpenAlex:	W4387575727

Citing:

DB	Citing
OpenAlex	12
Web of science	11

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