Brute-force solvent suppression for DNP studies of powders at natural isotopic abundance

Thureau, Pierre; Juramy, Marie; Ziarelli, Fabio; Viel, Stéphane; Mollica, Giulia

doi:10.1016/j.ssnmr.2019.02.002

Cited by 10 publications

(9 citation statements)

References 66 publications

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“…Several PA concentrations were tested, from 10 to 80 mM (Figure 3 and Supporting Information Figure S6) at 9.4 T. Interestingly, the sensitivity is optimal at around 40 mM radical solution for all three PAs. These results correlate with those reported by Thureau et al., [52] where higher PA concentrations were used to suppress the solvent signals and improve the overall sensitivity. Figure 3 reports the returned sensitivity at the optimal recycle delay time

T_{normalo normalp normalt}

(see Supporting Information, DNP build‐up analysis) for the three radicals at 40 mM.…”

Section: Resultssupporting

confidence: 91%

Highly Efficient Polarizing Agents for MAS‐DNP of Proton‐Dense Molecular Solids

et al. 2022

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Efficiently hyperpolarizing proton‐dense molecular solids through dynamic nuclear polarization (DNP) solid‐state NMR is still an unmet challenge. Polarizing agents (PAs) developed so far do not perform well on proton‐rich systems, such as organic microcrystals and biomolecular assemblies. Herein we introduce a new PA, cAsymPol‐POK, and report outstanding hyperpolarization efficiency on 12.76 kDa U‐13C,15N‐labeled LecA protein and pharmaceutical drugs at high magnetic fields (up to 18.8 T) and fast magic angle spinning (MAS) frequencies (up to 40 kHz). The performance of cAsymPol‐POK is rationalized by MAS‐DNP simulations combined with electron paramagnetic resonance (EPR), density functional theory (DFT) and molecular dynamics (MD). This work shows that this new biradical is compatible with challenging biomolecular applications and unlocks the rapid acquisition of 13C–13C and 15N–13C correlations of pharmaceutical drugs at natural isotopic abundance, which are key experiments for structure determination.

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T_{normalo normalp normalt}

(see Supporting Information, DNP build‐up analysis) for the three radicals at 40 mM.…”

Section: Resultssupporting

confidence: 91%

Highly Efficient Polarizing Agents for MAS‐DNP of Proton‐Dense Molecular Solids

et al. 2022

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“…Even when the solvent is partially deuterated, its 1 H and 13 C signals can mask those of the investigated materials. These solvent signals can be suppressed by various methods, including (i) the use of short contact times in CPMAS to selectively transfer the DNP-enhanced 1 H polarization to protonated 13 C nuclei of the investigated materials and not to deuterated 13 C sites of the solvent, (ii) the reintroduction of 13 C-2 H dipolar couplings, (iii) the use of relaxation filters, since for heterogeneous samples, such as a solid particles wetted by a PA solution, the nuclei in the solvent relax faster than those of the investigated material owing to their closer proximity to PA, and (iv) the impregnation of the sample with highly concentrated radical solutions, which results in rapid spin-lattice relaxation in the rotating frame and hence, low efficiency of the CPMAS transfer for the molecules of the frozen solvent [165,166,224]. After the coherent polarization transfer from protons to another isotope, additional pulse schemes have been applied to separate the isotropic and anisotropic interactions or to probe the internuclear connectivities and the proximities.…”

Section: Nmr Methodsmentioning

confidence: 99%

Recent developments in MAS DNP-NMR of materials

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et al. 2019

Solid State Nuclear Magnetic Resonance

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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.

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“…In addition, broad distributions of signals in the 1D surface-enhanced 13 C{ 1 H} DNP-CP-MAS spectra in the range 50–70 ppm from the frozen DNP solvent obscure the identification of 13 C signals associated with the sp 3 carbon sites of the DLC layer and PET polymer substrate. In this respect, solvent suppression methods − could be used to remove the solvent signals, although the weak 13 C signals originating from the DLC layer would likely also be suppressed during such experiments. In addition, partial dissolution of PET or other surface species into chlorinated solvents, such as CHCl 3 and TCE, may account for the additional 13 C signals in the aliphatic region (20–50 ppm) of 1D 13 C{ 1 H} CP-MAS spectra (Figure , Figures S3 and S4).…”

Section: Results and Discussionmentioning

confidence: 99%

Nanoscale Surface Compositions and Structures of Plasma-Modified Poly(ethylene terephthalate) Thin Films

et al. 2021

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Nanoscale compositions and structures of the plasma-treated surfaces of polymers often impart significant consequences on the barrier properties of thin films. Despite their technological importance for packaging and coating applications, a molecular-level understanding of their surface properties has been exceedingly challenging to obtain. This has been due to several factors, including their low external surface areas, nanometer-thin regions of surface modification, subtle differences between their surface versus bulk compositions, and the absence of long-range structural order. Nevertheless, recent advancements in solid-state nuclear magnetic resonance (NMR) spectroscopy, in particular using dynamic nuclear polarization (DNP) enhancement, in combination with X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy analyses provide detailed insights on the compositions of thin surface layers of plasma-modified poly(ethylene terephthalate) (PET) thin films. Analyses of 2D 13C{1H} DNP heteronuclear correlation (HETCOR) NMR spectra of plasma-modified PET films enabled signals from sp 3 carbon species associated with thin (30–80 nm) diamond-like carbon (DLC) surface layers to be detected and identified, along with their interactions at embedded DLC-PET interfaces. Complementary XPS spectra provide insights into different surface and subsurface elemental compositions of the plasma-modified PET films, which are corroborated by FT-IR analyses. Subsurface compositions and structures, in particular carbon:oxygen atomic ratios and intermixing of the DLC surface layers and PET regions, are shown to depend on plasma-enhanced chemical vapor deposition conditions, leading to different gas barrier properties of surface-modified PET films.

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Brute-force solvent suppression for DNP studies of powders at natural isotopic abundance

Cited by 10 publications

References 66 publications

Highly Efficient Polarizing Agents for MAS‐DNP of Proton‐Dense Molecular Solids

Highly Efficient Polarizing Agents for MAS‐DNP of Proton‐Dense Molecular Solids

Recent developments in MAS DNP-NMR of materials

Nanoscale Surface Compositions and Structures of Plasma-Modified Poly(ethylene terephthalate) Thin Films

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