Direct and Indirect Hyperpolarisation of Amines using Parahydrogen

TY - JOUR

T1 - Direct and Indirect Hyperpolarisation of Amines using Parahydrogen

AU - Iali, Wissam

AU - Rayner, Peter John

AU - Alshehri, Adel Mohammed M

AU - Holmes, J

AU - Ruddlesden, Amy Jane

AU - Duckett, Simon

N1 - This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details

PY - 2018/4/21

Y1 - 2018/4/21

N2 - Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are two widely used techniques for the study of molecules and materials. Hyperpolarisation methods, such as Signal Amplification By Reversible Exchange (SABRE), turn typically weak magnetic resonance responses into strong signals. In this article we detail how it is possible to hyperpolarise the 1H, 13C and 15N nuclei of a range of amines. This involved showing how primary amines form stable but labile complexes of the type [Ir(H)2(IMes)(amine)3]Cl that allow parahydrogen to relay its latent polarisation into the amine. By optimising the temperature and parahydrogen pressure a 1000-fold per proton NH signal gain for deuterated benzylamine is achieved at 9.4 T. Additionally, we show that sterically hindered and electron poor amines that bind poorly to iridium can be hyperpolarised by either employing a co-ligand for complex stabilisation, or harnessing the fact that it is possible to exchange hyperpolarised protons between amines in a mixture, through the recently reported SABRE-RELAY method. These chemical refinements have significant potential to extend the classes of agent that can be hyperpolarised by readily accessible parahydrogen.

AB - Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) are two widely used techniques for the study of molecules and materials. Hyperpolarisation methods, such as Signal Amplification By Reversible Exchange (SABRE), turn typically weak magnetic resonance responses into strong signals. In this article we detail how it is possible to hyperpolarise the 1H, 13C and 15N nuclei of a range of amines. This involved showing how primary amines form stable but labile complexes of the type [Ir(H)2(IMes)(amine)3]Cl that allow parahydrogen to relay its latent polarisation into the amine. By optimising the temperature and parahydrogen pressure a 1000-fold per proton NH signal gain for deuterated benzylamine is achieved at 9.4 T. Additionally, we show that sterically hindered and electron poor amines that bind poorly to iridium can be hyperpolarised by either employing a co-ligand for complex stabilisation, or harnessing the fact that it is possible to exchange hyperpolarised protons between amines in a mixture, through the recently reported SABRE-RELAY method. These chemical refinements have significant potential to extend the classes of agent that can be hyperpolarised by readily accessible parahydrogen.

UR - http://www.scopus.com/inward/record.url?scp=85045729772&partnerID=8YFLogxK

U2 - 10.1039/C8SC00526E

DO - 10.1039/C8SC00526E

M3 - Article

SN - 2041-6520

VL - 9

SP - 3677

EP - 3684

JO - Chemical Science

JF - Chemical Science

IS - 15

M1 - C8SC00526E

ER -