Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

Kobayashi, Takeshi; Lafon, Olivier; Thankamony, Aany Sofia Lilly; Slowing, Igor I.; Kandel, Kapil; Carnevale, Diego; Vitzthum, Veronika; Vezin, Hervé; Amoureux, Jean‐Paul; Bodenhausen, Geoffrey; Pruski, Marek

doi:10.1039/c3cp00039g

Cited by 76 publications

(77 citation statements)

References 59 publications

(189 reference statements)

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“…On the other hand, losses due to paramagnetic T 1r relaxation during CP partly cancel sensitivity gains resulting from CP from remote protons relayed by 1 H spin diffusion. 16 The enhancement e scan on/off = 1.7 is modest for 27 Al (Fig. S4b, ESI †).…”

Section: Larmor Frequenciesmentioning

confidence: 98%

“…When compared to standard room-temperature CP-MAS spectra of dry MIL-100(Al), DNP-CP-MAS at 100 K provides a global sensitivity enhancement of e time global = 10. 16 The TOTAPOL molecule is approximately 1.2 nm long and 0.65 nm wide. Hence, it can enter the large cavities of MIL-100(Al) through the hexagonal apertures of 0.88 nm (Fig.…”

Section: Larmor Frequenciesmentioning

confidence: 99%

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Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

et al. 2014

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We show how 27 Al-13 C proximities in the microporous metal-organic framework MIL-100(Al) can be probed using advanced 27 Al-13 C NMR methods boosted by Dynamic Nuclear Polarization.Metal-organic frameworks (MOFs) have attracted increasing attention owing to their high surface area and their wide range of three-dimensional (3D) architectures that exhibit different pore apertures and chemical tunabilities. These hybrid materials represent promising systems for gas storage, catalysis, capture of radioactive compounds, and drug delivery. 1 Amongst them, aluminium-based MOFs, such as MIL-100(Al), 2 present many advantages, including low cost, density and toxicity, remarkable thermal stability and high Lewis acidity that should allow many industrial applications. 3 Rational design of MOFs requires a clear understanding of structure-property relationships and hence calls for characterization methods endowed with atomic resolution. In particular, solid-state NMR is well suited to assess structural models of MOF frameworks, to probe the organization of extra-framework entities, 4 and to analyze atomic-level dynamics. 5,6 However, the poor sensitivity of NMR limits the observation of adsorbed species, defects, etc., particularly when the observed nuclei have low gyromagnetic ratios, low natural abundances or long longitudinal relaxation times (T 1 ). Besides, the observation of 27 Al-13 C proximities by NMR in Al-based MOFs has hitherto been hindered by limitations of common NMR probes, which cannot be tuned simultaneously to nearby 27 Al and 13 C Larmor frequencies. We report here the first observation of 27 Al-13 C proximities in MOFs using advanced NMR methods combined with a frequency splitter. 7,8 We show that Dynamic Nuclear Polarization (DNP) can significantly reduce acquisition times for MIL-100(Al) at 100 K. EPR spectroscopy and DNP enhancements prove that the biradical TOTAPOL 9 enters the MIL-100(Al) cavities within tens of minutes, although its apertures are smaller than 0.88 nm. Besides, DNP-enhanced 27 Al-13 C correlation experiments prove that the MIL-100(Al) framework is not altered by impregnation with a TOTAPOL solution. So far, DNP of MOFs has only been demonstrated for 1D spectra under Magic-Angle Spinning (MAS) using 1

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Section: Larmor Frequenciesmentioning

confidence: 98%

Section: Larmor Frequenciesmentioning

confidence: 99%

Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

et al. 2014

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“…Viewpoint systematic analysis of these contributions for functionalized mesoporous silica material can be found in ref 35. Importantly, Bruker has recently developed commercial DNP SSNMR instruments operated at 9.4, 14.1, and 18.8 T, with the corresponding gyrotron accessories at 263, 395, and 527 GHz, respectively.…”

Section: Acs Catalysismentioning

confidence: 99%

“…One of the major avenues that DNP enables is the study of unreceptive nuclei, such as 15 N, 17 O, 35 Cl, 43 Ca, 89 Y, and 119 Sn. Due to the difficulties in studying these nuclides, which may stem from low natural abundance, low value of γ, broad lineshapes, or any combination of these factors, they are often referred to as "exotic"; although, with DNP, this terminology may soon become obsolete.…”

Section: Dnp Ssnmr Of Challenging Nucleimentioning

confidence: 99%

Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

et al. 2015

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A revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2-3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound. Disciplines Chemistry CommentsReprinted (adapted) with permission from ACS Catalysis 5 (2015): 7055,

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“…The overall enhancements are even higher if one compares (i) the signal amplitudes of Ex-MSN amplified by DNP at 100 K with (ii) the conventional CPMAS spectrum of dry-Ex-MSN without DNP at room temperature under otherwise similar conditions. In a separate study, 39 this comparison was made per scan and for a given overall experimental time, after proper adjustments for the Boltzmann factor, paramagnetic quenching and effects of T 1 ( 1 H) relaxation. In the ensuing discussion, we first consider the enhancements ε on/of f ( 13 C) and ε on/of f ( The similarity between the ε on/of f ratios for 13 C and 29 Si is to be expected, since they both draw their polarization from the 1 H bath, and polarization losses must be due to relaxation during 1 H spin diffusion.…”

Section: Epr Spectra Of Ex-msn and S-msnmentioning

confidence: 99%

Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning ¹³C and ²⁹Si NMR Enhanced by Dynamic Nuclear Polarization

et al. 2013

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We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H-1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements εon/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to εon/off ≈ 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated. Disciplines Chemistry CommentsReprinted (adapted) with permission from Journal of Physical Chemistry C 117 (2013) ABSTRACT: We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13 C and 29 Si nuclei located in mesoporous organic/ inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1 H− 1 H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ε on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to ε on/off ≈ 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

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Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

Cited by 76 publications

References 59 publications

Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning ¹³C and ²⁹Si NMR Enhanced by Dynamic Nuclear Polarization

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Analysis of sensitivity enhancement by dynamic nuclear polarization in solid-state NMR: a case study of functionalized mesoporous materials

Cited by 76 publications

References 59 publications

Probing27Al–13C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Probing27Al–13C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

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Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Probing²⁷Al–¹³C proximities in metal–organic frameworks using dynamic nuclear polarization enhanced NMR spectroscopy

Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning ¹³C and ²⁹Si NMR Enhanced by Dynamic Nuclear Polarization