One- and Two-Dimensional 15N Exchange CP/MAS NMR Studies of the Structure and Electronic Properties of the Intermolecular N—H⋯N Hydrogen Bond in Imidazole Crystal

2001 ◽  
Vol 20 (3-4) ◽  
pp. 145-155 ◽  
Author(s):  
T. Ueda ◽  
H. Masui ◽  
N. Nakamura
Keyword(s):  
Hydrogen Bond ◽  
Electronic Properties ◽  
Mas Nmr ◽  
Two Dimensional ◽  
Nmr Studies ◽  
Cp Mas Nmr

NMR studies of 1-phenylazo-3-substituted-2-naphthols in solution and in the solid state

1990 ◽  
Vol 55 (1) ◽  
pp. 193-201 ◽  
Author(s):  
Antonín Lyčka ◽  
Miroslav Nečas ◽  
Josef Jirman ◽  
Jaroslav Straka ◽  
Bohdan Schneider
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Nmr Spectra ◽  
Equilibrium Mixture ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
Cp Mas Nmr ◽  
Hydrazone Form

The 1H and 15Nα-enriched 1-phenylazo-3-X-2-naphthols, where X = COOH (I), X = COOCH3 (II), and X = CONHC6H5 (III), have been measured in various solvents. The values of 1J(15Nα, H) and σ(15N) indicate that in CDCl3, C6D6, CCl4, and CD3NO2 solutions the compounds I and III exist practically completely in their hydrazone forms. The hydrazone form is stabilized by the hydrogen bond of COOH or CONH protons to the C(2)=O group. The compound II represents an equilibrium mixture of azo and hydrazone forms, since it cannot form a similar hydrogen bond. Moreover, the 15N NMR spectra of compounds I-III have been measured in solid state by the CP/MAS technique. The results indicate the existence of two conformers differing by the conformation of COOCH3 group in compound II, which is supported by the 13C CP/MAS NMR spectrum of compound II.

High-Field1H MAS and15N CP-MAS NMR Studies of Alanine Tripeptides and Oligomers:  Distinction of Antiparallel and Parallel β-Sheet Structures and Two Crystallographically Independent Molecules

2007 ◽  
Vol 111 (30) ◽  
pp. 9172-9178 ◽  
Author(s):  
Yu Suzuki ◽  
Michi Okonogi ◽  
Kazuo Yamauchi ◽  
Hiromichi Kurosu ◽  
Masataka Tansho ◽  
...  
Keyword(s):  
Mas Nmr ◽  
Nmr Studies ◽  
Independent Molecules ◽  
Cp Mas Nmr ◽  
Β Sheet

13C solid state CP/MAS NMR studies of EDTA complexes

1987 ◽  
Vol 129 (2) ◽  
pp. L23-L25 ◽  
Author(s):  
Silvio Aime ◽  
Roberto Gobetto ◽  
Rita Nano ◽  
Enrica Santucci
Keyword(s):  
Solid State ◽  
Mas Nmr ◽  
Nmr Studies ◽  
Edta Complexes ◽  
Cp Mas Nmr

XRD, FTIR and 13C CP/MAS NMR Studies of Composite Comprising Poly(vinyl acetate)-Silylated Si-MCM-41

2011 ◽  
Vol 364 ◽  
pp. 159-163
Author(s):  
Izza Taib Nurul ◽  
Salasiah Endud ◽  
M. Nasir Katun
Keyword(s):  
Carbonyl Group ◽  
Vinyl Acetate ◽  
Silica Matrix ◽  
Mas Nmr ◽  
Polymer Chains ◽  
Confined Space ◽  
Nmr Studies ◽  
Solution Intercalation ◽  
Cp Mas Nmr ◽  
Mcm 41

A composite structure based on silylated MCM-41 and Poly (vinyl acetate) (PVAc) was synthesized via solution intercalation. Poly (vinyl acetate)-silylated Si-MCM-41 composite were characterized by XRD, FTIR spectroscopy and13C CP/MAS NMR in order to determine the compatibility between PVAc and the silicate host. XRD study reveals that the framework of silylated Si-MCM-41 was not altered upon incorporation of PVAc. FTIR study showed that characteristic peak assigned to carbonyl group in PVAc was observed around 1741.6 cm-1for all the composites indicating the presence of PVAc in the silylated Si-MCM-41.13C CP/MAS NMR showed the increase of line width of the peak assigned to C=O carbonyl group indicating the increase in randomness of polymer chains in confined space. The shifting of the C=O carbonyl groups is a sign of the change in chemical environment of the carbonyl owing to the interaction of PVAc with the silica matrix of silylated Si-MCM-41.

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