Optimal sample formulations for DNP SENS: The importance of radical-surface interactions

Perras, Frédéric A.; Wang, Lin-Lin; Manzano, J. Sebastián; Chaudhary, Umesh; Opembe, Naftali N.; Johnson, Duane D.; Slowing, Igor I.; Pruski, Marek

doi:10.1016/j.cocis.2017.11.002

Cited by 44 publications

(55 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, low [PA] is preferred for long polarization transfers [123]. In the case of material impregnation with nitroxide biradicals, the [PA] producing highest sensitivity can range from a few to 30 mmol.L −1 [170]. Most high-field MAS DNP-NMR experiments on materials have been carried out on commercial systems manufactured by the Bruker BioSpin company (see Figure 9) [43,56].…”

Section: Sample Preparationmentioning

confidence: 99%

Recent developments in MAS DNP-NMR of materials

Rankin

Trébosc

Pourpoint

et al. 2019

Solid State Nuclear Magnetic Resonance

133

137

View full text Add to dashboard Cite

Solid-state NMR spectroscopy is a powerful technique for the characterization of the atomic-level structure and dynamics of materials. Nevertheless, the use of this technique is often limited by its lack of sensitivity, which can prevent the observation of surfaces, defects or insensitive isotopes. Dynamic Nuclear Polarization (DNP) has been shown to improve by one to three orders of magnitude the sensitivity of NMR experiments on materials under Magic-Angle Spinning (MAS), at static magnetic field B0 ≥ 5 T, conditions allowing for the acquisition of high-resolution spectra. The field of DNP-NMR spectroscopy of materials has undergone a rapid development in the last ten years, spurred notably by the availability of commercial DNP-NMR systems. We provide here an in-depth overview of MAS DNP-NMR studies of materials at high B0 field. After a historical perspective of DNP of materials, we describe the DNP transfers under MAS, the transport of polarization by spin diffusion and the various contributions to the overall sensitivity of DNP-NMR experiments. We discuss the design of tailored polarizing agents and the sample preparation in the case of materials. We present the DNP-NMR hardware and the influence of key experimental parameters, such as microwave power, magnetic field, temperature and MAS frequency. We give an overview of the isotopes, which have been detected by this technique, and the NMR methods, which have been combined with DNP. Finally, we show how MAS DNP-NMR has been applied to gain new insights into the structure of organic, hybrid and inorganic materials with applications in fields, such as health, energy, catalysis, optoelectronics etc.

show abstract

Section: Sample Preparationmentioning

confidence: 99%

Recent developments in MAS DNP-NMR of materials

Rankin

Trébosc

Pourpoint

et al. 2019

Solid State Nuclear Magnetic Resonance

133

137

View full text Add to dashboard Cite

show abstract

“…However, recording 13 C spectra or even more so correlation spectra in the absence of isotope enrichment with such small sample volume is typically not undertaken and has mostly been recently possible by using Dynamic Nuclear Polarization Surface Enhanced NMR spectroscopy. 8,9,[32][33][34] However, we show here that the development of 1 H detected experiments allows significantly boosting the spectral sensitivity, hence enabling various multidimensional experiments to be performed.…”

mentioning

confidence: 99%

“…8,9,[32][33][34] However, we show here that the development of 1 H detected experiments allows significantly boosting the spectral sensitivity, hence enabling various multidimensional experiments to be performed. In Figure 3A we show a 1 H detected heteronuclear 1 H- 13 C spectra had been acquired in a day with a substantial higher amount of sample. In order to further investigate the structures formed we performed a 1 H-51 V correlation experiment using the same D-HMQC sequence shown in Figure 3B.…”

mentioning

confidence: 99%

Proton-Detected Multidimensional Solid-State NMR Enables Precise Characterization of Vanadium Surface Species at Natural Abundance

Mance

Comas‐Vives

Copéret

2019

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

Heterogeneous catalysts fulfill vital roles in industrial process, however due to the nature of the catalytic surfaces typically containing either a low abundance of active sites and being amorphous in nature leads difficulties when attempting to study the structure of the active sites. In this work we show how making use of fast MAS ssNMR probes allows to efficiently detect well resolved 1 H detected spectra of heterogeneous catalysts. This approach was applied to study the structure of surface species resulting from the grafting of VO(OiPr)3 onto a partially dehydroxylated silica using the surface organometallic chemistry approach. The use of the 1 H sensitivity enabled to detect various hetero-and homo-nuclear correlation spectra in order to study the structure of this system and to resolve the structure of the grafted vanadium complex. More specifically, VO(OiPr)3 grafts through both protonolysis and opening of siloxane bridges to generate a bis-grafted species, in contrast to most other alkoxides.

show abstract

“…As can be seen by comparing the top 2 spectra in Figure 1, TEKPol yielded a 17 O direct DNP enhancement (ε DNP ) of 16, which was 4 times greater than the ε DNP afforded by trityl in water. The greater performance of TEKPol may be caused by its more favorable affinity toward the silica surface, which would lead to a greater association of the radical with the material, 13 the higher magnetic field used in this study (9.4 T) which may have led to a quenching of the cross-effect mechanism in trityl, and/or the application of MAS (previous experiments were Please do not adjust margins Please do not adjust margins performed on static samples 8a ). An AMUPol 14 /H 2 16 O solution provided a similar performance to TEKPol/TCE (see Figure S3), demonstrating that the solvent is not the determining factor.…”

Section: 89mentioning

confidence: 99%