Hyperpolarisation of weakly binding N-heterocycles using Signal Amplification by Reversible Exchange

TY - JOUR

T1 - Hyperpolarisation of weakly binding N-heterocycles using Signal Amplification by Reversible Exchange

AU - Rayner, Peter John

AU - Gillions, Joseph

AU - Hannibal, Valentin

AU - John, Richard Owain

AU - Duckett, Simon B.

N1 - © 2021 The Author(s). Published by the Royal Society of Chemistry.

PY - 2021/4/28

Y1 - 2021/4/28

N2 - Signal Amplification by Reversible Exchange (SABRE) is a catalytic method for improving the detection of molecules by magnetic resonance spectroscopy. It achieves this by simultaneously binding the target substrate (sub) and para-hydrogen to a metal centre. To date, sterically large substrates are relatively inacessable to SABRE due to their weak binding leading to catalyst destabilisation. We overcome this problem here through a simple co-ligand strategy that allows the hyperpolarisation of a range of weakly binding and sterically encumbered N-heterocycles. The resulting 1H NMR signal size is increased by up to 1400 times relative to their more usual Boltzmann controlled levels at 400 MHz. Hence, a significant reduction in scan time is achieved. The SABRE catalyst in these systems takes the form [IrX(H)2(NHC)(sulfoxide)(sub)] where X = Cl, Br or I. These complexes are shown to undergo very rapid ligand exchange and lower temperatures dramatically improves the efficiency of these SABRE catalysts.

AB - Signal Amplification by Reversible Exchange (SABRE) is a catalytic method for improving the detection of molecules by magnetic resonance spectroscopy. It achieves this by simultaneously binding the target substrate (sub) and para-hydrogen to a metal centre. To date, sterically large substrates are relatively inacessable to SABRE due to their weak binding leading to catalyst destabilisation. We overcome this problem here through a simple co-ligand strategy that allows the hyperpolarisation of a range of weakly binding and sterically encumbered N-heterocycles. The resulting 1H NMR signal size is increased by up to 1400 times relative to their more usual Boltzmann controlled levels at 400 MHz. Hence, a significant reduction in scan time is achieved. The SABRE catalyst in these systems takes the form [IrX(H)2(NHC)(sulfoxide)(sub)] where X = Cl, Br or I. These complexes are shown to undergo very rapid ligand exchange and lower temperatures dramatically improves the efficiency of these SABRE catalysts.

U2 - 10.1039/d0sc06907h

DO - 10.1039/d0sc06907h

M3 - Article

SN - 2041-6520

VL - 12

SP - 5910

EP - 5917

JO - Chemical Science

JF - Chemical Science

IS - 16

ER -