Predicting the DNP-SENS efficiency in reactive heterogeneous catalysts from hydrophilicity

Eva Pump, Anissa Bendjeriou-Sedjerari, Jasmine Viger-Gravel, David Gajan, Baptiste Scotto, Manoja K. Samantaray, Edy Abou-Hamad, Andrei Gurinov, Walid Almaksoud, Zhen Cao, Anne Lesage, Luigi Cavallo, Lyndon Emsley*, Jean Marie Basset

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Identification of surfaces at the molecular level has benefited from progress in dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS). However, the technique is limited when using highly sensitive heterogeneous catalysts due to secondary reaction of surface organometallic fragments (SOMFs) with stable radical polarization agents. Here, we observe that in non-porous silica nanoparticles (NPs) (dparticle = 15 nm) some DNP enhanced NMR or SENS characterizations are possible, depending on the metal-loading of the SOMF and the type of SOMF substituents (methyl, isobutyl, neopentyl). This unexpected observation suggests that aggregation of the nanoparticles occurs in non-polar solvents (such as ortho-dichlorobenzene) leading to (partial) protection of the SOMF inside the interparticle space, thereby preventing reaction with bulky polarization agents. We discover that the DNP SENS efficiency is correlated with the hydrophilicity of the SOMF/support, which depends on the carbon and SOMF concentration. Nitrogen sorption measurements to determine the BET constant (CBET) were performed. This constant allows us to predict the aggregation of silica nanoparticles and consequently the efficiency of DNP SENS. Under optimal conditions, CBET > 60, we found signal enhancement factors of up to 30.

Original languageEnglish (US)
Pages (from-to)4866-4872
Number of pages7
JournalChemical Science
Issue number21
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 The Royal Society of Chemistry.

ASJC Scopus subject areas

  • General Chemistry


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