Hyperpolarisation through reversible interactions with parahydrogen

Lyrelle S. Lloyd; Aziz Asghar; Michael J. Burns; Adrian Charlton; Steven Coombes; Michael J. Cowley; Gordon J. Dear; Simon B. Duckett; Georgi R. Genov; Gary G. R. Green; Louise A. R. Highton; Alexander J. J. Hooper; Majid Khan; Iman G. Khazal; Richard J. Lewis; Ryan E. Mewis; Andrew D. Roberts; Amy J. Ruddlesden

doi:10.1039/c4cy00464g

Hyperpolarisation through reversible interactions with parahydrogen

Lyrelle S. Lloyd^*, Aziz Asghar, Michael J. Burns, Adrian Charlton, Steven Coombes, Michael J. Cowley, Gordon J. Dear, Simon B. Duckett, Georgi R. Genov, Gary G. R. Green, Louise A. R. Highton, Alexander J. J. Hooper, Majid Khan, Iman G. Khazal, Richard J. Lewis, Ryan E. Mewis, Andrew D. Roberts, Amy J. Ruddlesden

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

We describe here how the complexes Ir(COD)(NHC)Cl [NHC = IMes, SIMes, IPr, SIPr, ICy, IMe and ImMe₂NPrⁱ ₂] provide significant insight into the catalytic process that underpins the hyperpolarization method signal amplification by reversible exchange (SABRE). These complexes react with pyridine and H₂to produce [Ir(H)₂(NHC)(py)₃]Cl which undergo ligand exchange on a timescale commensurate with good catalytic activity for the signal amplification by reversible exchange effect. This activity results from hydride ligand magnetic inequivalence and is highly dependent on the NHC. Variable temperature and kinetic studies demonstrate that rates of ligand loss which lie between 0.1 and 0.5 s^-1are ideal for catalysis. A role for the solvent complex [Ir(H)₂(MeOH)(NHC)(py)₂]Cl, which contains chemically inequivalent hydride ligands is revealed in the ligand exchange pathway. By optimisation of the conditions and NHC, a 5500-fold total pyridine signal enhancement is revealed when the NHC is IMes. Both T₁-reduction effects and HD exchange with the solvent are probed and shown to link to catalyst efficiency. The resulting signal enhancements suggest future in vivo MRI measurements under physiological conditions using this catalytic effect will be possible. This journal is

Original language	English
Pages (from-to)	3544-3554
Number of pages	11
Journal	Catalysis Science and Technology
Volume	4
Issue number	10
Early online date	11 Jul 2014
DOIs	https://doi.org/10.1039/c4cy00464g
Publication status	Published - 2 Oct 2014

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10.1039/c4cy00464g

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Lloyd, L. S., Asghar, A., Burns, M. J., Charlton, A., Coombes, S., Cowley, M. J., Dear, G. J., Duckett, S. B., Genov, G. R., Green, G. G. R., Highton, L. A. R., Hooper, A. J. J., Khan, M., Khazal, I. G., Lewis, R. J., Mewis, R. E., Roberts, A. D., & Ruddlesden, A. J. (2014). Hyperpolarisation through reversible interactions with parahydrogen. Catalysis Science and Technology, 4(10), 3544-3554. https://doi.org/10.1039/c4cy00464g

@article{3c076f18b71b44cba4a9a0c0c5acf6b1,

title = "Hyperpolarisation through reversible interactions with parahydrogen",

abstract = "We describe here how the complexes Ir(COD)(NHC)Cl [NHC = IMes, SIMes, IPr, SIPr, ICy, IMe and ImMe2NPri 2] provide significant insight into the catalytic process that underpins the hyperpolarization method signal amplification by reversible exchange (SABRE). These complexes react with pyridine and H2to produce [Ir(H)2(NHC)(py)3]Cl which undergo ligand exchange on a timescale commensurate with good catalytic activity for the signal amplification by reversible exchange effect. This activity results from hydride ligand magnetic inequivalence and is highly dependent on the NHC. Variable temperature and kinetic studies demonstrate that rates of ligand loss which lie between 0.1 and 0.5 s-1are ideal for catalysis. A role for the solvent complex [Ir(H)2(MeOH)(NHC)(py)2]Cl, which contains chemically inequivalent hydride ligands is revealed in the ligand exchange pathway. By optimisation of the conditions and NHC, a 5500-fold total pyridine signal enhancement is revealed when the NHC is IMes. Both T1-reduction effects and HD exchange with the solvent are probed and shown to link to catalyst efficiency. The resulting signal enhancements suggest future in vivo MRI measurements under physiological conditions using this catalytic effect will be possible. This journal is",

author = "Lloyd, {Lyrelle S.} and Aziz Asghar and Burns, {Michael J.} and Adrian Charlton and Steven Coombes and Cowley, {Michael J.} and Dear, {Gordon J.} and Duckett, {Simon B.} and Genov, {Georgi R.} and Green, {Gary G. R.} and Highton, {Louise A. R.} and Hooper, {Alexander J. J.} and Majid Khan and Khazal, {Iman G.} and Lewis, {Richard J.} and Mewis, {Ryan E.} and Roberts, {Andrew D.} and Ruddlesden, {Amy J.}",

year = "2014",

month = oct,

day = "2",

doi = "10.1039/c4cy00464g",

language = "English",

volume = "4",

pages = "3544--3554",

journal = "Catalysis Science and Technology",

issn = "2044-4753",

publisher = "The Royal Society of Chemistry",

number = "10",

}

Lloyd, LS, Asghar, A, Burns, MJ, Charlton, A, Coombes, S, Cowley, MJ, Dear, GJ, Duckett, SB, Genov, GR, Green, GGR, Highton, LAR, Hooper, AJJ, Khan, M, Khazal, IG, Lewis, RJ, Mewis, RE, Roberts, AD & Ruddlesden, AJ 2014, 'Hyperpolarisation through reversible interactions with parahydrogen', Catalysis Science and Technology, vol. 4, no. 10, pp. 3544-3554. https://doi.org/10.1039/c4cy00464g

TY - JOUR

T1 - Hyperpolarisation through reversible interactions with parahydrogen

AU - Lloyd, Lyrelle S.

AU - Asghar, Aziz

AU - Burns, Michael J.

AU - Charlton, Adrian

AU - Coombes, Steven

AU - Cowley, Michael J.

AU - Dear, Gordon J.

AU - Duckett, Simon B.

AU - Genov, Georgi R.

AU - Green, Gary G. R.

AU - Highton, Louise A. R.

AU - Hooper, Alexander J. J.

AU - Khan, Majid

AU - Khazal, Iman G.

AU - Lewis, Richard J.

AU - Mewis, Ryan E.

AU - Roberts, Andrew D.

AU - Ruddlesden, Amy J.

PY - 2014/10/2

Y1 - 2014/10/2

N2 - We describe here how the complexes Ir(COD)(NHC)Cl [NHC = IMes, SIMes, IPr, SIPr, ICy, IMe and ImMe2NPri 2] provide significant insight into the catalytic process that underpins the hyperpolarization method signal amplification by reversible exchange (SABRE). These complexes react with pyridine and H2to produce [Ir(H)2(NHC)(py)3]Cl which undergo ligand exchange on a timescale commensurate with good catalytic activity for the signal amplification by reversible exchange effect. This activity results from hydride ligand magnetic inequivalence and is highly dependent on the NHC. Variable temperature and kinetic studies demonstrate that rates of ligand loss which lie between 0.1 and 0.5 s-1are ideal for catalysis. A role for the solvent complex [Ir(H)2(MeOH)(NHC)(py)2]Cl, which contains chemically inequivalent hydride ligands is revealed in the ligand exchange pathway. By optimisation of the conditions and NHC, a 5500-fold total pyridine signal enhancement is revealed when the NHC is IMes. Both T1-reduction effects and HD exchange with the solvent are probed and shown to link to catalyst efficiency. The resulting signal enhancements suggest future in vivo MRI measurements under physiological conditions using this catalytic effect will be possible. This journal is

AB - We describe here how the complexes Ir(COD)(NHC)Cl [NHC = IMes, SIMes, IPr, SIPr, ICy, IMe and ImMe2NPri 2] provide significant insight into the catalytic process that underpins the hyperpolarization method signal amplification by reversible exchange (SABRE). These complexes react with pyridine and H2to produce [Ir(H)2(NHC)(py)3]Cl which undergo ligand exchange on a timescale commensurate with good catalytic activity for the signal amplification by reversible exchange effect. This activity results from hydride ligand magnetic inequivalence and is highly dependent on the NHC. Variable temperature and kinetic studies demonstrate that rates of ligand loss which lie between 0.1 and 0.5 s-1are ideal for catalysis. A role for the solvent complex [Ir(H)2(MeOH)(NHC)(py)2]Cl, which contains chemically inequivalent hydride ligands is revealed in the ligand exchange pathway. By optimisation of the conditions and NHC, a 5500-fold total pyridine signal enhancement is revealed when the NHC is IMes. Both T1-reduction effects and HD exchange with the solvent are probed and shown to link to catalyst efficiency. The resulting signal enhancements suggest future in vivo MRI measurements under physiological conditions using this catalytic effect will be possible. This journal is

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U2 - 10.1039/c4cy00464g

DO - 10.1039/c4cy00464g

M3 - Article

AN - SCOPUS:84907153403

SN - 2044-4753

VL - 4

SP - 3544

EP - 3554

JO - Catalysis Science and Technology

JF - Catalysis Science and Technology

IS - 10

ER -

Hyperpolarisation through reversible interactions with parahydrogen

Abstract

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Hyperpolarisation using SABRE as a new tool for imaging

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Signal Amplification in MR achieved through novel

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Hyperpolarisation through reversible interactions with parahydrogen

Abstract

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Hyperpolarisation using SABRE as a new tool for imaging

Signal Amplification in NMR and MRI using hyperpolarised compounds

Signal Amplification in MR achieved through novel

Cite this