Experimental evidence for the role of paramagnetic oxygen concentration on the decay of long-lived nuclear spin order
Experimental evidence for the role of paramagnetic oxygen concentration on the decay of long-lived nuclear spin order
Nuclear singlet lifetimes are often dependent on the quantity of paramagnetic oxygen species present in solution, although the extent to which quenching or removing molecular oxygen has on extending singlet lifetimes is typically an unknown factor. Here we investigate the behaviour of the singlet relaxation time constant as a function of the oxygen concentration in solution. An experimental demonstration is presented for a chemically inequivalent proton pair of the tripeptide alanine-glycine-glycine in solution. We introduce a simple methodology to ensure the solution is saturated with predetermined concentrations of oxygen gas prior to measurements of the singlet lifetime. Singlet lifetimes were measured by using the spin-lock induced crossing pulse sequence. We present a linear relationship between the amount of oxygen dissolved in solution and the singlet relaxation rate constant. Singlet relaxation was found to be ∼2.7 times less sensitive to relaxation induced by paramagnetic oxygen compared with longitudinal relaxation. The relaxation behaviour is described by using a model of correlated fluctuating fields. We additionally examine the extension of singlet lifetimes by doping solutions with the chelating agent sodium ascorbate, which scavenges oxygen radicals in solution.
23418-23424
Erriah, Bryan
91ea7a25-8fc0-4922-898b-65cbd9dad8ce
Elliott, Stuart J.
6cc724de-f75f-4c0f-a00a-e712b4e73b12
2019
Erriah, Bryan
91ea7a25-8fc0-4922-898b-65cbd9dad8ce
Elliott, Stuart J.
6cc724de-f75f-4c0f-a00a-e712b4e73b12
Erriah, Bryan and Elliott, Stuart J.
(2019)
Experimental evidence for the role of paramagnetic oxygen concentration on the decay of long-lived nuclear spin order.
RSC Advances, 9 (40), .
(doi:10.1039/c9ra03748a).
Abstract
Nuclear singlet lifetimes are often dependent on the quantity of paramagnetic oxygen species present in solution, although the extent to which quenching or removing molecular oxygen has on extending singlet lifetimes is typically an unknown factor. Here we investigate the behaviour of the singlet relaxation time constant as a function of the oxygen concentration in solution. An experimental demonstration is presented for a chemically inequivalent proton pair of the tripeptide alanine-glycine-glycine in solution. We introduce a simple methodology to ensure the solution is saturated with predetermined concentrations of oxygen gas prior to measurements of the singlet lifetime. Singlet lifetimes were measured by using the spin-lock induced crossing pulse sequence. We present a linear relationship between the amount of oxygen dissolved in solution and the singlet relaxation rate constant. Singlet relaxation was found to be ∼2.7 times less sensitive to relaxation induced by paramagnetic oxygen compared with longitudinal relaxation. The relaxation behaviour is described by using a model of correlated fluctuating fields. We additionally examine the extension of singlet lifetimes by doping solutions with the chelating agent sodium ascorbate, which scavenges oxygen radicals in solution.
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c9ra03748a
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Accepted/In Press date: 9 July 2019
e-pub ahead of print date: 29 July 2019
Published date: 2019
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Local EPrints ID: 436435
URI: http://eprints.soton.ac.uk/id/eprint/436435
ISSN: 2046-2069
PURE UUID: 768b5510-bf22-4bf8-8bcd-e01428eeab1a
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Date deposited: 10 Dec 2019 17:30
Last modified: 05 Jun 2024 17:59
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Author:
Bryan Erriah
Author:
Stuart J. Elliott
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