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 journalArticlepeer-review

35 Scopus citations


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 languageEnglish (US)
Pages (from-to)12812-12817
Number of pages6
JournalRSC Advances
Issue number33
StatePublished - Dec 21 2012

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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