TY - JOUR

T1 - Efficient conversion of anti-phase spin order of protons into 15N magnetisation using SLIC-SABRE

AU - Knecht, Stephan

AU - Kiryutin, Alexey S.

AU - Yurkovskaya, Alexandra V.

AU - Ivanov, Konstantin L.

PY - 2019/10/2

Y1 - 2019/10/2

N2 - SABRE (Signal Amplification By Reversible Exchange) is a technique for enhancement of NMR (Nuclear Magnetic Resonance) signals, which utilises parahydrogen (pH 2, the H 2 molecule in its nuclear singlet spin state) as a source of non-thermal spin order. In SABRE experiments, pH 2 binds transiently to an organometallic complex with a to-be-polarised substrate; subsequently, spin order transfer takes place and the substrate acquires non-thermal spin polarisation resulting in strong NMR signal enhancement. In this work, we argue that the spin order of H 2 in SABRE experiments performed at high magnetic fields is not necessarily the singlet order but rather anti-phase polarisation, S1zS2z. Although SABRE exploits pH 2, i.e. the starting spin order of H 2 is supposed to be the singlet order, in solution, S−T 0 conversion becomes efficient once pH 2 binds to a complex. Such a variation of the spin order, which becomes S1zS2z, has an important consequence: NMR methods used for transferring SABRE polarisation need to be modified. Here we demonstrate that methods proposed for the initial singlet order may not work for the S1zS2z order; however, a simple modification makes them efficient again.

AB - SABRE (Signal Amplification By Reversible Exchange) is a technique for enhancement of NMR (Nuclear Magnetic Resonance) signals, which utilises parahydrogen (pH 2, the H 2 molecule in its nuclear singlet spin state) as a source of non-thermal spin order. In SABRE experiments, pH 2 binds transiently to an organometallic complex with a to-be-polarised substrate; subsequently, spin order transfer takes place and the substrate acquires non-thermal spin polarisation resulting in strong NMR signal enhancement. In this work, we argue that the spin order of H 2 in SABRE experiments performed at high magnetic fields is not necessarily the singlet order but rather anti-phase polarisation, S1zS2z. Although SABRE exploits pH 2, i.e. the starting spin order of H 2 is supposed to be the singlet order, in solution, S−T 0 conversion becomes efficient once pH 2 binds to a complex. Such a variation of the spin order, which becomes S1zS2z, has an important consequence: NMR methods used for transferring SABRE polarisation need to be modified. Here we demonstrate that methods proposed for the initial singlet order may not work for the S1zS2z order; however, a simple modification makes them efficient again.

KW - parahydrogen

KW - polarisation transfer

KW - SABRE method

KW - Spin hyperpolarisation

KW - spin order

KW - PARA-HYDROGEN

KW - NMR

KW - KINETICS

KW - HYPERPOLARIZATION

KW - MECHANISMS

KW - PARAHYDROGEN

KW - POLARIZATION TRANSFER

UR - http://www.scopus.com/inward/record.url?scp=85053260706&partnerID=8YFLogxK

U2 - 10.1080/00268976.2018.1515999

DO - 10.1080/00268976.2018.1515999

M3 - Article

AN - SCOPUS:85053260706

VL - 117

SP - 2762

EP - 2771

JO - Molecular Physics

JF - Molecular Physics

SN - 0026-8976

IS - 19

ER -