Deactivation of catalysts in simultaneous reversible and irreversible parahydrogen NMR signal enhancement, and the role of co-ligands in the stabilization of the reversible method

Mames, Adam; Jopa, Sylwia; Pietrzak, Mariusz; Ratajczyk, Tomasz

doi:10.1039/d2ra02872g

“…The same situation could be observed in acetone-d 6 , i.e., PNL disappeared, but signals from coordinated cyclooctadiene were still visible. We did not observe PNL in the case when [44][45][46] ) involved in the activation of IrÀ IMes (R=Mes) and IrÀ IMesBn (R=Bn), L=Py or DMSO. The hydrogenation process of COD operates during the formation of the SABRE active complex (C5).…”

Section: Methodscontrasting

confidence: 57%

“…The plausible scenario of the activation is presented in Scheme 2. In this process, several consecutive chemical reactions operate, and various transient species (for example, C1−C4 ) are created [44–46] . As a result of the activation, the pre‐catalyst's structure is rearranged step by step into its final form, C5 .…”

Section: Methodsmentioning

confidence: 99%

A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line

Czarnota,

Mames,

Pietrzak

et al. 2024

Angew Chem Int Ed

Self Cite

0

View full text Add to dashboard Cite

The hydrogen molecule, which exists in two spin isomers (ortho‐ and parahydrogen), is a highly studied system due to its fundamental properties and practical applications. Parahydrogen is used for Nuclear Magnetic Resonance signal enhancement, which is hyperpolarization of other molecules, including biorelevant ones. Hyperpolarization can be achieved by using Signal Amplification by Reversible Exchange (SABRE). SABRE can also convert parahydrogen into orthohydrogen, and surprisingly, in some cases, it has been discovered that orthohydrogen’s resonance has the Partially Negative Line (PNL) pattern. Here, an approach for obtaining orthohydrogen with a PNL signal is presented for two catalysts: Ir‐IMes, and Ir‐IMesBn. The type of solvent in which SABRE is conducted is crucial for the observation of PNL. Specifically, a PNL signal can be easily generated in benzene using both catalysts, but it is more intense for Ir‐IMesBn. In acetone, PNL is observed only for Ir‐IMesBn. In methanol, no PNL is detected. The PNL effect is only detectable during the initial steps of pre‐catalyst activation, and disappears as the activation process progresses. We have proposed a working hypothesis that explains our results. The presented data may facilitate the further investigation of PNL and its applications in material science and catalysis.

show abstract

“…In this process, several consecutive chemical reactions operate, and various transient species (for example, C1À C4) are created. [44][45][46] As a result of the activation, the pre-catalyst's structure is rearranged step by step into its final form, C5. Here, we will hypothesize which transient species can be potentially concerned with the occurrence of PNL.…”

Section: Methodsmentioning

confidence: 99%

“…Scheme 2. Hypothetical chemical rearrangements (based on literature data[44][45][46] ) involved in the activation of IrÀ IMes (R=Mes) and IrÀ IMesBn (R=Bn), L=Py or DMSO. The hydrogenation process of COD operates during the formation of the SABRE active complex (C5).…”

mentioning

confidence: 99%

A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line

Czarnota,

Mames,

Pietrzak

et al. 2024

Angewandte Chemie

Self Cite

0

View full text Add to dashboard Cite

The hydrogen molecule, which exists in two spin isomers (ortho‐ and parahydrogen), is a highly studied system due to its fundamental properties and practical applications. Parahydrogen is used for Nuclear Magnetic Resonance signal enhancement, which is hyperpolarization of other molecules, including biorelevant ones. Hyperpolarization can be achieved by using Signal Amplification by Reversible Exchange (SABRE). SABRE can also convert parahydrogen into orthohydrogen, and surprisingly, in some cases, it has been discovered that orthohydrogen’s resonance has the Partially Negative Line (PNL) pattern. Here, an approach for obtaining orthohydrogen with a PNL signal is presented for two catalysts: Ir‐IMes, and Ir‐IMesBn. The type of solvent in which SABRE is conducted is crucial for the observation of PNL. Specifically, a PNL signal can be easily generated in benzene using both catalysts, but it is more intense for Ir‐IMesBn. In acetone, PNL is observed only for Ir‐IMesBn. In methanol, no PNL is detected. The PNL effect is only detectable during the initial steps of pre‐catalyst activation, and disappears as the activation process progresses. We have proposed a working hypothesis that explains our results. The presented data may facilitate the further investigation of PNL and its applications in material science and catalysis.

show abstract

“…The experiments utilized [Ir(COD)(IMes)Cl], a common pre-catalyst in SABRE hyperpolarization studies. 19,20 SABRE experiments were conducted with 15 minutes of activation (see ESI †), followed by pH 2 bubbling for 30-90 seconds at 1-3 atm, precisely controlled with a needle valve and pressure gauge. A low magnetic fields, manipulated through direct current (DC) power supply connected to a solenoid coil (see ESI †), were employed based on level anti-crossing (LACs) theory.…”

mentioning

confidence: 99%

SABRE hyperpolarization of nicotinamide derivatives and their molecular dynamics properties

Luu,

Nguyen,

Manh

et al. 2024

Analyst

1

0

View full text Add to dashboard Cite

show abstract

Deactivation of catalysts in simultaneous reversible and irreversible parahydrogen NMR signal enhancement, and the role of co-ligands in the stabilization of the reversible method

Abstract: Signal Amplification by Reversible Exchange (SABRE) and hydrogeneable Parahydrogen Induced Polarization (hPHIP) can enhance weak NMR signals, and thus increase the range of NMR applications.

Cited by 4 publications

References 48 publications

A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line

A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line

A Straightforward Method for the Generation of Hyperpolarized Orthohydrogen with a Partially Negative Line

SABRE hyperpolarization of nicotinamide derivatives and their molecular dynamics properties

Contact Info

Product

Resources

About