TY - JOUR

T1 - 15N SABRE Hyperpolarization of Metronidazole at Natural Isotope Abundance

AU - Kiryutin, Alexey S.

AU - Yurkovskaya, Alexandra V.

AU - Ivanov, Konstantin L.

N1 - Funding Information: This work has been supported by the Russian Science Foundation (grant No. 20‐62‐47038). We acknowledge the Russian Ministry of Science and Higher Education for giving access to NMR facilities. Publisher Copyright: © 2021 Wiley-VCH GmbH Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/7/16

Y1 - 2021/7/16

N2 - Signal Amplification By Reversible Exchange (SABRE) is gaining increased attention as a tool to enhance weak Nuclear Magnetic Resonance (NMR) signals. In SABRE, spin order is transferred from parahydrogen (H2 in its nuclear singlet spin state) to a substrate molecule in a transient Ir-based complex. In recent years, SABRE polarization of biologically active substrates has been demonstrated, notably of metronidazole – an antibiotic and antiprotozoal drug. In this work, we study 15N SABRE polarization of metronidazole at natural isotope abundance. We are able to demonstrate significant 15N polarization reaching 15 %, which corresponds to a signal enhancement of 46,000 at 9.4 T for the nitrogen atom with lone electron pair. Additionally, the other two N-atoms can be polarized, although less efficiently. We present a detailed study of the field dependence of polarization and explain the maxima in the field dependence using the concept of coherent polarization transfer at level anti-crossings in the SABRE complex. A study of spin relaxation phenomena presented here enables optimization of the magnetic field for efficient storage of non-thermal polarization.

AB - Signal Amplification By Reversible Exchange (SABRE) is gaining increased attention as a tool to enhance weak Nuclear Magnetic Resonance (NMR) signals. In SABRE, spin order is transferred from parahydrogen (H2 in its nuclear singlet spin state) to a substrate molecule in a transient Ir-based complex. In recent years, SABRE polarization of biologically active substrates has been demonstrated, notably of metronidazole – an antibiotic and antiprotozoal drug. In this work, we study 15N SABRE polarization of metronidazole at natural isotope abundance. We are able to demonstrate significant 15N polarization reaching 15 %, which corresponds to a signal enhancement of 46,000 at 9.4 T for the nitrogen atom with lone electron pair. Additionally, the other two N-atoms can be polarized, although less efficiently. We present a detailed study of the field dependence of polarization and explain the maxima in the field dependence using the concept of coherent polarization transfer at level anti-crossings in the SABRE complex. A study of spin relaxation phenomena presented here enables optimization of the magnetic field for efficient storage of non-thermal polarization.

KW - metronidazole

KW - parahydrogen

KW - SABRE method

KW - spin hyperpolarization

UR - http://www.scopus.com/inward/record.url?scp=85107707901&partnerID=8YFLogxK

U2 - 10.1002/cphc.202100315

DO - 10.1002/cphc.202100315

M3 - Article

C2 - 34009704

AN - SCOPUS:85107707901

VL - 22

SP - 1470

EP - 1477

JO - ChemPhysChem

JF - ChemPhysChem

SN - 1439-4235

IS - 14

ER -