TY - JOUR

T1 - Theoretical description of hyperpolarization formation in the SABRE-relay method

AU - Knecht, Stephan

AU - Barskiy, Danila A.

AU - Buntkowsky, Gerd

AU - Ivanov, Konstantin L.

N1 - Funding Information: K.L.I. acknowledges support from the Russian Science Foundation (Project No. 19-43-04116), and G.B. acknowledges financial support from the Deutsche Forschungsgemeinschaft under Contract No. Bu-911-29-1. Publisher Copyright: © 2020 Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/10/28

Y1 - 2020/10/28

N2 - SABRE (Signal Amplification By Reversible Exchange) has become a widely used method for hyper-polarizing nuclear spins, thereby enhancing their Nuclear Magnetic Resonance (NMR) signals by orders of magnitude. In SABRE experiments, the non-equilibrium spin order is transferred from parahydrogen to a substrate in a transient organometallic complex. The applicability of SABRE is expanded by the methodology of SABRE-relay in which polarization can be relayed to a second substrate either by direct chemical exchange of hyperpolarized nuclei or by polarization transfer between two substrates in a second organometallic complex. To understand the mechanism of the polarization transfer and study the transfer efficiency, we propose a theoretical approach to SABRE-relay, which can treat both spin dynamics and chemical kinetics as well as the interplay between them. The approach is based on a set of equations for the spin density matrices of the spin systems involved (i.e., SABRE substrates and complexes), which can be solved numerically. Using this method, we perform a detailed study of polarization formation and analyze in detail the dependence of the attainable polarization level on various chemical kinetic and spin dynamic parameters. We foresee the applications of the present approach for optimizing SABRE-relay experiments with the ultimate goal of achieving maximal NMR signal enhancements for substrates of interest.

AB - SABRE (Signal Amplification By Reversible Exchange) has become a widely used method for hyper-polarizing nuclear spins, thereby enhancing their Nuclear Magnetic Resonance (NMR) signals by orders of magnitude. In SABRE experiments, the non-equilibrium spin order is transferred from parahydrogen to a substrate in a transient organometallic complex. The applicability of SABRE is expanded by the methodology of SABRE-relay in which polarization can be relayed to a second substrate either by direct chemical exchange of hyperpolarized nuclei or by polarization transfer between two substrates in a second organometallic complex. To understand the mechanism of the polarization transfer and study the transfer efficiency, we propose a theoretical approach to SABRE-relay, which can treat both spin dynamics and chemical kinetics as well as the interplay between them. The approach is based on a set of equations for the spin density matrices of the spin systems involved (i.e., SABRE substrates and complexes), which can be solved numerically. Using this method, we perform a detailed study of polarization formation and analyze in detail the dependence of the attainable polarization level on various chemical kinetic and spin dynamic parameters. We foresee the applications of the present approach for optimizing SABRE-relay experiments with the ultimate goal of achieving maximal NMR signal enhancements for substrates of interest.

KW - HYDROGEN INDUCED POLARIZATION

KW - DISSOCIATION REACTION STAGES

KW - INTEGRAL ENCOUNTER THEORY

KW - REVERSIBLE EXCHANGE

KW - N-15 HYPERPOLARIZATION

KW - HIGH-FIELD

KW - SPIN HYPERPOLARIZATION

KW - SIGNAL AMPLIFICATION

KW - MULTISTAGE REACTIONS

KW - NMR

UR - http://www.scopus.com/inward/record.url?scp=85094808323&partnerID=8YFLogxK

U2 - 10.1063/5.0023308

DO - 10.1063/5.0023308

M3 - Article

C2 - 33138423

AN - SCOPUS:85094808323

VL - 153

SP - 164106

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 16

M1 - 164106

ER -