Solid-state bromination of poly(1,6-di-N-carbazolyl-2,4-hexadiyne): a cross polarization-magic angle spinning NMR study

1987 ◽  
Vol 109 (3) ◽  
pp. 761-768 ◽  
Author(s):  
Hellmut Eckert ◽  
James P. Yesinowski ◽  
Daniel J. Sandman ◽  
Christopher S. Velazquez
Keyword(s):  
Solid State ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
Nmr Study ◽  
Angle Spinning

Solid-state 17O NMR Study of Small Biological Compounds

2007 ◽  
Vol 62 (11) ◽  
pp. 1422-1432 ◽  
Author(s):  
Kazuhiko Yamada ◽  
Tadashi Shimizu ◽  
Yoshida Mitsuru ◽  
Miwako Asanuma ◽  
Masataka Tansho ◽  
...  
Keyword(s):  
Solid State ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Multiple Quantum ◽  
Peptide Analysis ◽  
17O Nmr ◽  
Nmr Study ◽  
Biological Compounds ◽  
Nmr Tensors ◽  
Angle Spinning

We present a systematic experimental and theoretical investigation of the oxygen chemical shielding and electric-field-gradient tensors in polycrystalline amino acids and a peptide. Analysis of the 17O magic-angle-spinning (MAS), multiple-quantum MAS, and stationary nuclear magnetic resonance (NMR) spectra yield the magnitudes and the relative orientations between the two NMR tensors. The obtained 17O NMR parameters are sensitive to the hydrogen bond environments. We also demonstrate that solid-state 17O NMR is potentially useful for studying the secondary structures of peptides and proteins.

scholarly journals New Condensation Polymer Precursors Containing Consecutive Silicon Atoms—Decaisopropoxycyclopentasilane and Dodecaethoxyneopentasilane—And Their Sol–Gel Polymerization

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 841
Author(s):  
Sung Jin Park ◽  
Myong Euy Lee ◽  
Hyeon Mo Cho ◽  
Sangdeok Shim
Keyword(s):  
Solid State ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Cross Polarization ◽  
Reaction Conditions ◽  
Polymer Precursors ◽  
Sol Gel Process ◽  
Angle Spinning ◽  
Magnetic Resonances

The sol–gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon–organic composites. The development of new sol–gel precursors is very important for obtaining new types of sol–gel products. New condensation polymer precursors containing consecutive silicon atoms—decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)—were synthesized for the preparation of polysilane–polysiloxane material. The CPS and NPS xerogels were prepared by the sol–gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N2 physisorption measurements (Brunauer–Emmett–Teller; BET and Brunauer-Joyner-Halenda; BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol–gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane–polysiloxane.

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