scholarly journals Two- and three-dimensional multinuclear stray-field imaging of rotating samples with magic-angle spinning (STRAFI-MAS): From bio to inorganic materials

2010 ◽  
Vol 32 (2) ◽  
pp. 418-423 ◽  
Author(s):  
Alan Wong ◽  
Dimitris Sakellariou
Keyword(s):  
Three Dimensional ◽  
Magic Angle Spinning ◽  
Inorganic Materials ◽  
Stray Field ◽  
Magic Angle ◽  
Angle Spinning ◽  
Field Imaging ◽  
Stray Field Imaging

Three-Dimensional NMR Spectroscopy of Fluorinated Pharmaceutical Solids under Ultrafast Magic Angle Spinning

2019 ◽  
Vol 91 (9) ◽  
pp. 6217-6224 ◽  
Author(s):  
Xingyu Lu ◽  
Daniel Skomski ◽  
Karen C. Thompson ◽  
Michael J. McNevin ◽  
Wei Xu ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Three Dimensional ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Pharmaceutical Solids ◽  
Angle Spinning

scholarly journals Uptake and Release of Species from Carbohydrate Containing Organogels and Hydrogels

Gels ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 43 ◽  
Author(s):  
Abhishek Pan ◽  
Saswati G. Roy ◽  
Ujjal Haldar ◽  
Rita D. Mahapatra ◽  
Garry R. Harper ◽  
...  
Keyword(s):  
Raft Polymerization ◽  
Three Dimensional ◽  
Magic Angle Spinning ◽  
Bioactive Molecules ◽  
Magic Angle ◽  
Ability To Act ◽  
Reversible Addition ◽  
Methacrylate Monomer ◽  
Angle Spinning ◽  
Cp Mas Nmr

Hydrogels are used for a variety of technical and medical applications capitalizing on their three-dimensional (3D) cross-linked polymeric structures and ability to act as a reservoir for encapsulated species (potentially encapsulating or releasing them in response to environmental stimuli). In this study, carbohydrate-based organogels were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of a β-D-glucose pentaacetate containing methacrylate monomer (Ac-glu-HEMA) in the presence of a di-vinyl cross-linker; these organogels could be converted to hydrogels by treatment with sodium methoxide (NaOMe). These materials were studied using solid state 13C cross-polarization/magic-angle spinning (CP/MAS) NMR, Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FE-SEM). The swelling of the gels in both organic solvents and water were studied, as was their ability to absorb model bioactive molecules (the cationic dyes methylene blue (MB) and rhodamine B (RhB)) and absorb/release silver nitrate, demonstrating such gels have potential for environmental and biomedical applications.

Interfaces Involving Biomolecules and Inorganic Materials: a Solid State NMR Approach

2007 ◽  
Vol 1008 ◽  
Author(s):  
Christian Bonhomme ◽  
Geoffrey Hartmeyer ◽  
Florence Babonneau ◽  
Michel Wong Chi Man ◽  
Guilhem Arrachart ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Chemical Nature ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Inorganic Materials ◽  
Double Quantum ◽  
Magic Angle ◽  
Angle Spinning ◽  
Very High

AbstractMaterials based on ureidopyrimidinone (UPY) dimers and Adenine (A) / Thymine (T) derivatives were synthesized and characterized by advanced solid state NMR (Nuclear Magnetic Resonance) techniques. Silylated UPY molecules were used as model compounds, leading to structured organic-inorganic materials after hydrolysis and condensation processes (sol-gel reactions). High resolution 1H solid state NMR has been extensively used for the in-depth description of the H-bond networks, including very fast MAS (Magic Angle Spinning) experiments at very high field and DQ (double quantum) recoupling experiments. The chemical nature of the organic-inorganic interface has been illuminated by such techniques. In, particular, it has been demonstrated that H-bond networks were preserved during sol-gel reactions and were comparable to those observed in the UPY crystalline precursors.

Ab initio powder structure determination and thermal behavior of a new lead(II) phenylphosphonate, Pb(O3PC6H5)

1996 ◽  
Vol 52 (6) ◽  
pp. 982-988 ◽  
Author(s):  
A. Cabeza ◽  
M. A. G. Aranda ◽  
M. Martinez-Lara ◽  
S. Bruque ◽  
J. Sanz
Keyword(s):  
Thermal Behavior ◽  
Three Dimensional ◽  
Direct Methods ◽  
Magic Angle Spinning ◽  
Dimensional Structure ◽  
Magic Angle ◽  
Nmr Studies ◽  
Final Agreement ◽  
Angle Spinning ◽  
Difference Fourier

The crystal structure of Pb(O3PC6H5) has been solved from X-ray powder diffraction data. Crystal data: triclinic, a = 13.6907 (5), b = 9.3327 (4), c = 7.0432 Å, α = 106.188 (3), β = 94.927, γ = 96.977°, V = 851.04 (8) Å3, space group P{\bar 1} and Z = 4. Initial positional parameters for Pb atoms were obtained from direct methods using 556 structure factors in the 2θ range 9–63°. All remaining non-H atoms were located from successive difference-Fourier maps. The final agreement factors were R wp = 0.055, Rp = 0.042 and RF = 0.017. There are 22 atoms in the asymmetric part of the unit cell and 66 positional parameters have been refined with the help of soft constraints. The lead coordination environment is irregular due to a marked inert pair effect. The three-dimensional structure of this organic inorganic compound is layered with inorganic layers built up from CPO3 tetrahedra and PbO6 units. 31P MAS and CP-MAS (cross-polarization magic angle spinning) NMR studies have been carried out to confirm the triclinic symmetry with two independent structural units. In optimum conditions two 31P resonance signals are observed, indicating that there are two crystallographically independent P atoms with closely similar environments. The thermal behavior of this material has been studied and the thermal decomposition products identified.

Geopolymers for the Immobilization of Radioactive Waste

2004 ◽  
Vol 824 ◽  
Author(s):  
D S Perera ◽  
M G Blackford ◽  
E R Vance ◽  
J V Hanna ◽  
K S Finnie ◽  
...  
Keyword(s):  
Fly Ash ◽  
Three Dimensional ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Transmission Electron ◽  
Alkali Solutions ◽  
Infra Red ◽  
Angle Spinning

AbstractGeopolymers are made by adding aluminosilicates to concentrated alkali solutions for dissolution and subsequent polymerization to form a solid. They are amorphous to semicrystalline three dimensional aluminosilicate networks. Although they have been used in several applications their widespread use is restricted due to lack of long term durability studies and detailed scientific understanding. Three important tools for the study of geopolymers are transmission electron microscopy (TEM), solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and infra red (IR) spectroscopy.Cs and Sr are two of the most difficult radionuclides to immobilize and are therefore suitable elements to study in assessing geopolymers as matrices for immobilization of radioactive wastes. In this study Cs or Sr was added to geopolymer samples prepared using fly ash precursors. A commercial metakaolinite geopolymer was studied for comparison.The geopolymers were mainly amorphous as shown by TEM, whether they were made from fly ash or metakaolinite. In the fly ash geopolymer, Cs preferentially inhabited the amorphous phase over the minor crystalline phases, whereas Sr was shared in both. The MAS NMR showed that Cs is held mostly in the geopolymer structure for both fly ash and metakaolinite geopolymers. The IR spectra showed a slight shift in antisymmetric Si-O-Al stretch band to a lower wavenumber for the fly ash geopolymer, which implies that more Al is incorporated in this geopolymer structure than in the metakaolinite geopolymer.

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