The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy

Lloyd Lumata; Matthew Merritt; Chalermchai Khemtong; S. James Ratnakar; Johan Van Tol; Lu Yu; Likai Song; Zoltan Kovacs

doi:10.1039/c2ra21853d

The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy

Lloyd Lumata, Matthew Merritt, Chalermchai Khemtong, S. James Ratnakar, Johan Van Tol, Lu Yu, Likai Song, Zoltan Kovacs

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

35 Scopus citations

Abstract

The free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for ¹³C, ¹⁵N, ⁸⁹Y, and ¹⁰⁹Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.

Original language	English (US)
Pages (from-to)	12812-12817
Number of pages	6
Journal	RSC Advances
Volume	2
Issue number	33
DOIs	https://doi.org/10.1039/c2ra21853d
State	Published - Dec 21 2012

ASJC Scopus subject areas

Chemistry(all)
Chemical Engineering(all)

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abstract = "The free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for 13C, 15N, 89Y, and 109Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.",

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AU - Lumata, Lloyd

AU - Merritt, Matthew

AU - Khemtong, Chalermchai

AU - Ratnakar, S. James

AU - Van Tol, Johan

AU - Yu, Lu

AU - Song, Likai

AU - Kovacs, Zoltan

PY - 2012/12/21

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N2 - The free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for 13C, 15N, 89Y, and 109Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.

AB - The free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for 13C, 15N, 89Y, and 109Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.

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The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy

Abstract

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