1
|
Tickner BJ, Zhivonitko VV. Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications. Chem Sci 2022; 13:4670-4696. [PMID: 35655870 PMCID: PMC9067625 DOI: 10.1039/d2sc00737a] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 03/21/2022] [Indexed: 12/18/2022] Open
Abstract
Parahydrogen-induced polarisation (PHIP) is a nuclear spin hyperpolarisation technique employed to enhance NMR signals for a wide range of molecules. This is achieved by exploiting the chemical reactions of parahydrogen (para-H2), the spin-0 isomer of H2. These reactions break the molecular symmetry of para-H2 in a way that can produce dramatically enhanced NMR signals for reaction products, and are usually catalysed by a transition metal complex. In this review, we discuss recent advances in novel homogeneous catalysts that can produce hyperpolarised products upon reaction with para-H2. We also discuss hyperpolarisation attained in reversible reactions (termed signal amplification by reversible exchange, SABRE) and focus on catalyst developments in recent years that have allowed hyperpolarisation of a wider range of target molecules. In particular, recent examples of novel ruthenium catalysts for trans and geminal hydrogenation, metal-free catalysts, iridium sulfoxide-containing SABRE systems, and cobalt complexes for PHIP and SABRE are reviewed. Advances in this catalysis have expanded the types of molecules amenable to hyperpolarisation using PHIP and SABRE, and their applications in NMR reaction monitoring, mechanistic elucidation, biomedical imaging, and many other areas, are increasing.
Collapse
Affiliation(s)
- Ben J Tickner
- NMR Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 Oulu 90014 Finland
- Department of Chemical and Biological Physics, Faculty of Chemistry, Weizmann Institute of Science Rehovot 7610001 Israel
| | - Vladimir V Zhivonitko
- NMR Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 Oulu 90014 Finland
| |
Collapse
|
2
|
Lin K, TomHon P, Lehmkuhl S, Laasner R, Theis T, Blum V. Density Functional Theory Study of Reaction Equilibria in Signal Amplification by Reversible Exchange. Chemphyschem 2021; 22:1947-1957. [PMID: 34549869 DOI: 10.1002/cphc.202100204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 05/19/2021] [Indexed: 11/07/2022]
Abstract
An in-depth theoretical analysis of key chemical equilibria in Signal Amplification by Reversible Exchange (SABRE) is provided, employing density functional theory calculations to characterize the likely reaction network. For all reactions in the network, the potential energy surface is probed to identify minimum energy pathways. Energy barriers and transition states are calculated, and harmonic transition state theory is applied to calculate exchange rates that approximate experimental values. The reaction network energy surface can be modulated by chemical potentials that account for the dependence on concentration, temperature, and partial pressure of molecular constituents (hydrogen, methanol, pyridine) supplied to the experiment under equilibrium conditions. We show that, under typical experimental conditions, the Gibbs free energies of the two key states involved in pyridine-hydrogen exchange at the common Ir-IMes catalyst system in methanol are essentially the same, i. e., nearly optimal for SABRE. We also show that a methanol-containing intermediate is plausible as a transient species in the process.
Collapse
Affiliation(s)
- Kailai Lin
- Department of Chemistry, Duke University, Durham, NC 27708, USA
| | - Patrick TomHon
- Department of Chemistry, North Carolina State University, Raleigh, NC 27606, USA
| | - Sören Lehmkuhl
- Department of Chemistry, North Carolina State University, Raleigh, NC 27606, USA
| | - Raul Laasner
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| | - Thomas Theis
- Department of Chemistry, North Carolina State University, Raleigh, NC 27606, USA.,Joint Department of Biomedical Engineering, UNC, Chapel Hill, and NC State University, Raleigh, NC 27606, USA.,Department of Physics, North Carolina State University, Raleigh, NC 27606, USA
| | - Volker Blum
- Department of Chemistry, Duke University, Durham, NC 27708, USA.,Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
| |
Collapse
|
3
|
Vaneeckhaute E, De Ridder S, Tyburn JM, Kempf JG, Taulelle F, Martens JA, Breynaert E. Long-Term Generation of Longitudinal Spin Order Controlled by Ammonia Ligation Enables Rapid SABRE Hyperpolarized 2D NMR. Chemphyschem 2021; 22:1170-1177. [PMID: 33851495 DOI: 10.1002/cphc.202100079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/29/2021] [Indexed: 01/19/2023]
Abstract
Symmetry breaking of parahydrogen using iridium catalysts converts singlet spin order into observable hyperpolarization. In this contribution, iridium catalysts are designed to exhibit asymmetry in their hydrides, regulated by in situ generation of deuterated ammonia governed by ammonium buffers. The concentrations of ammonia (N) and pyridine (P) provide a handle to generate a variety of stereo-chemically asymmetric N-heterocyclic carbene iridium complexes, ligating either [3xP], [2xP;N], [P;2xN] or [3xN] in an octahedral SABRE type configuration. The non-equivalent hydride positions, in correspondence with the ammonium buffer solutions, enables to extend singlet-triplet or S ⟩ → T 0 ⟩ mixing at high magnetic field and experimentally induce prolonged generation of non-equilibrium longitudinal two-spin order. This long-lasting magnetization can be exploited in hyperpolarized 2D-OPSY-COSY experiments providing direct structural information on the catalyst using a single contact with parahydrogen. Separately, field cycling revealed hyperpolarization properties in low-field conditions. Controlling catalyst stereochemistry by introducing small and deuterated ligands, such as deuterated ammonia, simplifies the spin-system. This is shown to unify experimental and theoretically derived field-sweep experiments for four-spin systems.
Collapse
Affiliation(s)
- Ewoud Vaneeckhaute
- COK-kat, Centre for Surface Chemistry and Catalysis-Characterisation and Application Team, KU Leuven, Celestijnenlaan 200F, box 2461, B-3001, Leuven, Belgium.,NMRCoRe, NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F, box 2461, 3001, Leuven, Belgium
| | - Sophie De Ridder
- COK-kat, Centre for Surface Chemistry and Catalysis-Characterisation and Application Team, KU Leuven, Celestijnenlaan 200F, box 2461, B-3001, Leuven, Belgium
| | - Jean-Max Tyburn
- Bruker Biospin, 34 rue de l'Industrie BP 10002, 67166, Wissembourg Cedex, France
| | - James G Kempf
- Bruker Biospin, 15 Fortune Dr., Billerica, 01821, Massachusetts, United States
| | - Francis Taulelle
- COK-kat, Centre for Surface Chemistry and Catalysis-Characterisation and Application Team, KU Leuven, Celestijnenlaan 200F, box 2461, B-3001, Leuven, Belgium.,NMRCoRe, NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F, box 2461, 3001, Leuven, Belgium
| | - Johan A Martens
- COK-kat, Centre for Surface Chemistry and Catalysis-Characterisation and Application Team, KU Leuven, Celestijnenlaan 200F, box 2461, B-3001, Leuven, Belgium.,NMRCoRe, NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F, box 2461, 3001, Leuven, Belgium
| | - Eric Breynaert
- COK-kat, Centre for Surface Chemistry and Catalysis-Characterisation and Application Team, KU Leuven, Celestijnenlaan 200F, box 2461, B-3001, Leuven, Belgium.,NMRCoRe, NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F, box 2461, 3001, Leuven, Belgium
| |
Collapse
|
4
|
Mandal R, Pham P, Hilty C. Nuclear Spin Hyperpolarization of NH 2 - and CH 3 -Substituted Pyridine and Pyrimidine Moieties by SABRE. Chemphyschem 2020; 21:2166-2172. [PMID: 32783276 DOI: 10.1002/cphc.202000483] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/23/2020] [Indexed: 01/06/2023]
Abstract
Hyperpolarization of N-heterocycles with signal amplification by reversible exchange (SABRE) induces NMR sensitivity gains for biological molecules. Substitutions with functional groups, in particular in the ortho-position of the heterocycle, however, result in low polarization using a typical Ir catalyst with a bis-mesityl N-heterocyclic carbene ligand for SABRE, presumably due to steric hindrance. With the addition of allylamine or acetonitrile as coligands to the precatalyst chloro(1,5-cyclooctadiene)[4,5-dimethyl-1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] iridium, the 1 H signal enhancement increased in several substrates with ortho NH2 substitutions. For example, for a proton in 2,4-diaminopyrimidine, the enhancement factors increased from -7±1 to -210±20 with allylamine or to -160±10 with acetonitrile. CH3 substituted molecules yielded maximum signal enhancements of -25±7 with acetonitrile addition, which is considerably less than the corresponding NH2 substituted molecules, despite exhibiting similar steric size. With the more electron-donating NH2 substitution resulting in greater enhancement, it is concluded that steric hindrance is not the only dominant factor in determining the polarizability of the CH3 substituted compounds. The addition of allylamine increased the signal enhancement for the 290 Da trimethoprim, a molecule with a 2,4-diaminopyrimidine moiety serving as an antibacterial agent, to -70.
Collapse
Affiliation(s)
- Ratnamala Mandal
- Department of Chemistry, Texas A&M University, College Station, TX, 77843-3255, USA
| | - Pierce Pham
- Department of Chemistry, Texas A&M University, College Station, TX, 77843-3255, USA
| | - Christian Hilty
- Department of Chemistry, Texas A&M University, College Station, TX, 77843-3255, USA
| |
Collapse
|