TY - JOUR

T1 - Re-polarization of nuclear spins using selective SABRE-INEPT

AU - Knecht, Stephan

AU - Kiryutin, Alexey S.

AU - Yurkovskaya, Alexandra V.

AU - Ivanov, Konstantin L.

N1 - Publisher Copyright: © 2017

PY - 2018/2/1

Y1 - 2018/2/1

N2 - A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH2, the H2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes “re-polarization”, i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε. For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε≈260 for 15N nuclei, whereas SABRE-INEPT with re-polarization yields ε>2000. We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques.

AB - A method is proposed for significant improvement of NMR pulse sequences used in high-field SABRE (Signal Amplification By Reversible Exchange) experiments. SABRE makes use of spin order transfer from parahydrogen (pH2, the H2 molecule in its singlet spin state) to a substrate in a transient organometallic Ir-based complex. The technique proposed here utilizes “re-polarization”, i.e., multiple application of an NMR pulse sequence used for spin order transfer. During re-polarization only the form of the substrate, which is bound to the complex, is excited by selective NMR pulses and the resulting polarization is transferred to the free substrate via chemical exchange. Owing to the fact that (i) only a small fraction of the substrate molecules is in the bound form and (ii) spin relaxation of the free substrate is slow, the re-polarization scheme provides greatly improved NMR signal enhancement, ε. For instance, when pyridine is used as a substrate, single use of the SABRE-INEPT sequence provides ε≈260 for 15N nuclei, whereas SABRE-INEPT with re-polarization yields ε>2000. We anticipate that the proposed method is useful for achieving maximal NMR enhancement with spin hyperpolarization techniques.

KW - Parahydrogen

KW - Polarization transfer

KW - SABRE

KW - Spin hyperpolarization

KW - PARA-HYDROGEN

KW - NMR-SPECTROSCOPY

KW - MAGNETIZATION

KW - HETERONUCLEI

KW - HIGH-FIELD

KW - REVERSIBLE EXCHANGE

KW - ENHANCEMENT

KW - PARAHYDROGEN-INDUCED POLARIZATION

KW - CROSS-POLARIZATION

KW - HYPERPOLARIZATION

UR - http://www.scopus.com/inward/record.url?scp=85038836082&partnerID=8YFLogxK

U2 - 10.1016/j.jmr.2017.12.010

DO - 10.1016/j.jmr.2017.12.010

M3 - Article

C2 - 29274936

AN - SCOPUS:85038836082

VL - 287

SP - 10

EP - 14

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

SN - 1090-7807

ER -