Exploring the hyperpolarisation of EGTA-based ligands using SABRE

Tickner, Ben. J.; Borozdina, Yulia; Duckett, Simon B.; Angelovski, Goran

doi:10.1039/d0dt03839c

Cited by 4 publications

(4 citation statements)

References 57 publications

(125 reference statements)

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“…Ir–NHC catalysts are typically highly soluble in organic solvents and therefore polarisation transfer reactions are typically performed in methanol- d 4 (ref. 29 , 38 , 146 , 157 and 158 ) or even dichloromethane- d 2 , 37,38 chloroform- d 159 or ethanol- d 6 . 146 The efficiency of SABRE catalysis in other solvents can be improved by alteration of the auxiliary NHC ligand.…”

Section: Reversible Reactions With Para-h 2 and Po...mentioning

confidence: 99%

“…A more effective way to create stable SABRE catalysts in cases where [Ir(H) 2 (NHC)(substrate) 3 ]Cl is not formed due to sterically large, or weakly-ligating, substrates is the use of coligand-supported catalysts. 158,166 For example, coordination of pyridine-derived substrates with functionality in the ortho position that hinders iridium ligation can be facilitated by a coligand. 150, 166 To demonstrate, 1 H NMR signal enhancements up to 1442 AE 84fold were recorded for 2,5-lutidine using catalysts of the form [IrCl(H) 2 (NHC)(sulfoxide)(substrate)].…”

Section: Coligand-supported Sabre Catalysts To Hyperpolarise Sterical...mentioning

confidence: 99%

“…For bulky substrates, formation of [Ir(H) 2 (IMes)(substrate) 3 ]Cl may be prevented by steric effects. 118,150,158 The use of catalysts with sterically smaller auxiliary ligands, such as phosphines, 150 asymmetric carbenes, 164 or bidentate carbenes 165 can be used to form SABRE catalysts with bulkier substrate ligands. A more effective way to create stable SABRE catalysts in cases where [Ir(H) 2 (NHC)(substrate) 3 ]Cl is not formed due to sterically large, or weakly-ligating, substrates is the use of coligand-supported catalysts.…”

Section: Reversible Reactions With Para-h2 and Polarisation Transfer ...mentioning

confidence: 99%

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Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications

Tickner

Живонитко

2022

Chem. Sci.

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Section: Reversible Reactions With Para-h 2 and Po...mentioning

confidence: 99%

Section: Coligand-supported Sabre Catalysts To Hyperpolarise Sterical...mentioning

confidence: 99%

Section: Reversible Reactions With Para-h2 and Polarisation Transfer ...mentioning

confidence: 99%

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Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications

Tickner

Живонитко

2022

Chem. Sci.

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“…Co-substrates, often named co-ligands, have also proved useful for the hyperpolarization of weakly coordinating analytes. Examples are the enhancements of the hyperpolarization of acetonitrile in methanol with Ir-IMes, with or without an additional PCy 3 ligand, by pyridine, 26 of amines by acetonitrile or mtz, 27 of o -NH 2 -substituted pyridines and pyrimidines by acetonitrile or allylamine, 15 and of pyruvate 28 and ketoisocaproate 29 by dimethyl sulfoxide.…”

Section: Analysis Of Dilute Solutions With Sabre/nhphipmentioning

confidence: 99%

Analysis of Complex Mixtures by Chemosensing NMR Using para-Hydrogen-Induced Hyperpolarization

Fraser¹,

Rutjes²,

Feiters³

et al. 2022

Acc. Chem. Res.

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Conspectus Nuclear magnetic resonance (NMR) is a powerful technique for chemical analysis. The use of NMR to investigate dilute analytes in complex systems is, however, hampered by its relatively low sensitivity. An additional obstacle is represented by the NMR signal overlap. Because solutes in a complex mixture are usually not isotopically labeled, NMR studies are often limited to 1 H measurements, which, because of the modest dispersion of the 1 H resonances (typically ∼10 ppm), can result in challenging signal crowding. The low NMR sensitivity issue can be alleviated by nuclear spin hyperpolarization (i.e., transiently increasing the differences in nuclear spin populations), which determines large NMR signal enhancements. This has been demonstrated for hyperpolarization methods such as dynamic nuclear polarization, spin-exchange optical pumping and para -hydrogen-induced polarization (PHIP). In particular, PHIP has grown into a fast, efficient, and versatile technique since the recent discovery of non-hydrogenative routes to achieve nuclear spin hyperpolarization. For instance, signal amplification by reversible exchange (SABRE) can generate proton as well as heteronuclear spin hyperpolarization in a few seconds in compounds that are able to transiently bind to an iridium catalyst in the presence of para -hydrogen in solution. The hyperpolarization transfer catalyst acts as a chemosensor in the sense that it is selective for analytes that can coordinate to the metal center, such as nitrogen-containing aromatic heterocycles, sulfur heteroaromatic compounds, nitriles, Schiff bases, diaziridines, carboxylic acids, and amines. We have demonstrated that the signal enhancement achieved by SABRE allows rapid NMR detection and quantification of a mixture of substrates down to low-micromolar concentration. Furthermore, in the transient complex, the spin configuration of p -H 2 can be easily converted to spin hyperpolarization to produce up to 1000-fold enhanced NMR hydride signals. Because the hydrides’ chemical shifts are highly sensitive to the structure of the analyte associating with the iridium complex, they can be employed as hyperpolarized “probes” to signal the presence of specific compounds in the mixture. This indirect detection of the analytes in solution provides important benefits in the case of complex systems, as hydrides resonate in a region of the 1 H spectrum (at ca. −20 ppm) that is generally signal-free. The enhanced sensitivity provided by non-hydrogenative PHIP (nhPHIP), together with the absence of interference from the complex matrix (usually resonating between 0 and 10 ppm), set the detection limit for this NMR chemosensor down to sub-μM concentrations, approximately 3 orders of magnitude lower than for conventional NMR. This nhPHIP approach represents, therefore, a powerful tool for NMR analysis of dilut...

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Hyperpolarised benchtop NMR spectroscopy for analytical applications

Silva Terra,

Taylor,

Halse

2024

Progress in Nuclear Magnetic Resonance Spectroscopy

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Exploring the hyperpolarisation of EGTA-based ligands using SABRE

Abstract: We prepared a series of EGTA-derived metal-ion chelators and explored their suitability for hyperpolarisation with parahydrogen using the SABRE technique.

Cited by 4 publications

References 57 publications

Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications

Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications

Analysis of Complex Mixtures by Chemosensing NMR Using para-Hydrogen-Induced Hyperpolarization

Hyperpolarised benchtop NMR spectroscopy for analytical applications

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