Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

doi:10.1021/acscatal.5b02039

Cited by 172 publications

(203 citation statements)

References 69 publications

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“…The establishment of the molecular-level relationships between the structural and catalytic properties of Sn-modified materials requires additional dedicated and detailed studies combining advanced characterization [64][65][66] and thorough kinetic and operando studies 67 complemented by computations on realistic chemical models 68,69 accounting for the complexity of Sn-zeolite sugar conversion catalyst systems.…”

Section: View Article Onlinementioning

confidence: 99%

Influence of pore topology on synthesis and reactivity of Sn-modified zeolite catalysts for carbohydrate conversions

Graaff

Tempelman

Pidko

et al. 2017

Catal. Sci. Technol.

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A range of Sn-modified MWW, MFI, MOR and Beta zeolites were prepared by a post-synthetic Sn functionalization method and their catalytic properties for sugar conversions were evaluated. The focus of this work was to understand the effect of micropore dimensions and additional mesoporosity on the Sn incorporation and on the catalytic properties. The post-synthetic approach, which involves aciddealumination of the parent zeolite followed by SnCl 4 grafting, is highly efficient for the selective incorporation of lattice Sn sites in wide-pore Beta and MOR zeolites. The modification of the medium-pore MWW and MFI is impaired by the more difficult dealumination and hence the lower efficiency of the Sn incorporation. Hierarchical structuring of the zeolites allows the increase of the Sn loading in the final zeolites. The catalytic properties were assessed in the isomerization and retro-aldolization reactions of glucose and the conversion of 1,3-dihydroxyacetone to methyl lactate. The catalytic results depend strongly on the structural and topological properties of the catalysts as well as on the reactant. Glucose isomerization carried out at a relatively low temperature is mainly limited by strong adsorption of carbohydrates to the active sites. This explains why zeolite nanostructuring had little effect on the catalyst activity, which instead depends mainly on the zeolite topology and the nature of the reactive Sn centers. The influence of pore size is most pronounced for Sn-MWW and Sn-MFI zeolites which are inactive in glucose-to-fructose isomerization, but perform in the higher-temperature retro-aldolization of carbohydrates with an activity similar to that of Sn-Beta. Because of the limited accessibility of the Sn sites inside the 1D MOR pore system, Sn-MOR catalysts were only moderately active in all probe reactions considered.

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Section: View Article Onlinementioning

confidence: 99%

Influence of pore topology on synthesis and reactivity of Sn-modified zeolite catalysts for carbohydrate conversions

Graaff

Tempelman

Pidko

et al. 2017

Catal. Sci. Technol.

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“…It should be noted that, in addition to the PHIP technique, the low intrinsic sensitivity of NMR spectroscopy in catalysis can be overcome by an emerging technique named dynamic nuclear polarization surface‐enhanced NMR spectroscopy (DNP SENS) . DNP SENS can increase the NMR signal intensity of conventional NMR spectra by one to two orders of magnitude, and has been successfully applied to a wide range of surface systems …”

Section: Single‐site Catalysts In the Context Of Nmr Sensitivity Imprmentioning

confidence: 99%

Single‐Site Heterogeneous Catalysts: From Synthesis to NMR Signal Enhancement

Burueva

Kovtunova

Bukhtiyarov

et al. 2018

Chemistry A European J

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Catalysts with well-defined, single, active centers are of great importance and their utilization allows the gap between homo- and heterogeneous catalysis to be bridged and, importantly, the main selectivity problem of heterogeneous catalysis and the main separation challenge of homogeneous catalysis to be overcome. Moreover, the use of single-site catalysts allows the NMR signal to be significantly enhanced through the pairwise addition of two hydrogen atoms from a parahydrogen molecule to an unsaturated substrate. This review covers the fundamentals of the synthesis of single-site catalysts and shows the new aspects of their applications in both modern catalysis and the field of parahydrogen-based hyperpolarization. The different novel aspects of the formation and utilization of single-site catalysts, along with the possibility of NMR signal enhancement observations are described.

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“…= 0.37%) of 15 N. Therefore higher sensitivity and shorter acquisition time make DNP-enhanced solid-state NMR a very powerful tool to unravel the local structure of widely used N-containing active groups such as amino acids 61 and catalyst ligands like bipyridine or N-heterocyclic carbenes grafted on hybrid solids. 62,63 Having identified the key interactions predicted to be at play in the peptide-functionalized MIL-68-NHPro and MIL-68-NH-Gly-Pro, and in particular the stabilization of the grafted amino acids through interactions with the MOF framework, we compare the 15 N NMR signatures generated from combined DFT/MD computations with those recorded experimentally from 1 H-15 N DNP SENS CPMAS spectra. This allowed us to (i) validate the computational models and (ii) confirm the experimentally assigned chemical shifts of nitrogen species in amino acids-functionalized MOFs.…”

Section: N Chemical Shifts In Peptide Functionalized Mofsmentioning

confidence: 99%

Molecular Level Characterization of the Structure and Interactions in Peptide‐Functionalized Metal–Organic Frameworks

Todorova

Rozanska

Gervais

et al. 2016

Chemistry A European J

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We use DFT, newly parameterized Molecular Dynamics simulations and last generation 15 N DNP surface enhanced solid-state NMR spectroscopy to understand graft-host interactions and effects imposed by the MOF host on peptide conformations in a peptide-functionalized MOF. Focusing on two grafts typified by MIL-68-Proline (-Pro) and MIL-68-Glycine-Proline (-Gly-Pro), we identified the most likely peptide conformations adopted in the functionalized hybrid frameworks. We found that hydrogen bond interactions between the graft and the surface hydroxyl groups of the MOF are key in determining the peptides conformation(s).15 N DNP SENS methodology shows unprecedented signal enhancements when applied to these peptide-functionalized MOFs. The calculated chemical shifts of selected MIL-68-NH-Pro and MIL-68-NH-Gly-Pro conformations are in a good agreement with the experimentally obtained 15 N NMR signals. The study shows that the conformations of peptides when grafted in a MOF host are unlikely to be freely distributed, and conformational selection is directed by strong host-guest interactions.

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Dynamic Nuclear Polarization Solid-State NMR in Heterogeneous Catalysis Research

Cited by 172 publications

References 69 publications

Influence of pore topology on synthesis and reactivity of Sn-modified zeolite catalysts for carbohydrate conversions

Influence of pore topology on synthesis and reactivity of Sn-modified zeolite catalysts for carbohydrate conversions

Single‐Site Heterogeneous Catalysts: From Synthesis to NMR Signal Enhancement

Molecular Level Characterization of the Structure and Interactions in Peptide‐Functionalized Metal–Organic Frameworks

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