DNP-supported solid-state NMR studies of 13C,15N,29Si-enriched biosilica of Cyclotella cryptica and Thalassiosira pseudonana

AbstractSolid-state NMR spectroscopy represents a powerful method for the investigation of diatom biosilica but detailed studies regarding its chemical composition and structural organization can be prohibited by insufficient spectroscopic sensitivity. Here, we used two-dimensional (2D) Dynamic Nuclear Polarization (DNP)-supported solid-state NMR experiments to obtain information about the molecular composition and supramolecular organization of proteins and carbohydrates in 13C,15N,29Si-labeled biosilica of C. cryptica. As a reference, we conducted DNP experiments on isotope-labeled biosilica of T. pseudonana. DNP-enhancement factors for different NMR signals, and thus, for different organic compounds, provide information about the supramolecular architecture of the biosilica. In addition, DNP-supported heteronuclear nitrogen-carbon correlation experiments allowed us to prove the presence of different structural elements of long chain polyamines (LCPAs) and revealed the occurrence of amine-nitrogen moieties exhibiting a correlation with carbonyl carbons that may indicate cross-linking of LCPAs to proteins as previously seen in studies on proteins extracted from other diatoms.

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DNP-Supported Solid-State NMR Studies of 13C,15N,29Si-Enriched Biosilica of Cyclotella Cryptica and Thalassiosira Pseudonana

10.21203/rs.3.rs-44217/v1 ◽

2020 ◽

Author(s):

Helena Ehren ◽

Felicitas Kolbe ◽

Alesandra Lucini Paioni ◽

Eike Brunner ◽

Marc Baldus

Keyword(s):

Solid State ◽

Solid State Nmr ◽

Nuclear Polarization ◽

Thalassiosira Pseudonana ◽

Supramolecular Organization ◽

Powerful Method ◽

Nmr Studies ◽

Amine Nitrogen ◽

Nmr Signals ◽

Cyclotella Cryptica

Abstract Solid-state NMR spectroscopy represents a powerful method for the investigation of diatom biosilica but detailed studies regarding its chemical composition and structural organization can be prohibited by insufficient spectroscopic sensitivity. Here, we used two-dimensional (2D) Dynamic Nuclear Polarization (DNP)-supported solid-state NMR experiments to obtain information about the molecular composition and supramolecular organization of proteins and carbohydrates in13C,15N,29Si-labeled biosilica of C. cryptica. As a reference, we conducted DNP experiments on isotope-labeled biosilica of T. pseudonana. DNP-enhancement factors for different NMR signals, and thus, for different organic compounds, provide information about the supramolecular architecture of the biosilica. In addition, DNP-supported heteronuclear nitrogen-carbon correlation experiments allowed us to prove the presence of different LCPAs (long chain polyamines) and revealed the occurrence of amine-nitrogen moieties exhibiting a correlation with carbonyl carbons that may indicate cross-linking of LCPAs to proteins as previously seen in studies on proteins extracted from other diatoms.

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Effect of aluminum and sodium on the sorption of water and methanol in microporous MFI-type zeolites and mesoporous SBA-15 materials

Adsorption ◽

10.1007/s10450-020-00275-8 ◽

2020 ◽

Cited By ~ 1

Author(s):

Zheng Li ◽

Carolin Rieg ◽

Ann-Katrin Beurer ◽

Michael Benz ◽

Johannes Bender ◽

...

Keyword(s):

Solid State ◽

Solid State Nmr ◽

Acid Sites ◽

Mas Nmr ◽

Nmr Studies ◽

Oh Groups ◽

Adsorption Sites ◽

Low Field ◽

Strong Adsorption ◽

Nmr Signals

Abstract The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66–74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44–60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15.

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The Atomic-Level Structure of Cementitious Calcium Aluminate Silicate Hydrate Determined by NMR

CHIMIA International Journal for Chemistry ◽

10.2533/chimia.2021.272 ◽

2021 ◽

Vol 75 (4) ◽

pp. 272-275

Author(s):

Pinelopi Moutzouri ◽

Lyndon Emsley

Keyword(s):

Solid State ◽

Calcium Aluminate ◽

First Principles ◽

Solid State Nmr ◽

Nuclear Polarization ◽

Level Structure ◽

Atomic Level ◽

Two Dimensional ◽

First Principles Calculations ◽

Nmr Signals

We review our recent paper which resolves the long-standing dilemma of the location and nature of the six-fold coordinated aluminum in calcium aluminate silicate hydrate (C-A-S-H) samples. First principles calculations predict that at high Ca:Si and H2O ratios, aluminum is incorporated into the bridging sites of the linear silicate chains and that the stable coordination number is six. We confirm this hypothesis experimentally by one- and two-dimensional dynamic nuclear polarization enhanced 27 Al and 29 Si solid-state NMR experiments in which we correlate the distinctive six-fold coordinated aluminum NMR signal at 5 ppm to 29 Si NMR signals from silicates in C-A-S-H.

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