scholarly journals Water in cellulose: evidence and identification of immobile and mobile adsorbed phases by 2H MAS NMR

2017 ◽  
Vol 19 (6) ◽  
pp. 4360-4369 ◽  
Author(s):  
E. L. Lindh ◽  
C. Terenzi ◽  
L. Salmén ◽  
I. Furó
Keyword(s):  
Physical Chemistry ◽  
Mas Nmr ◽  
Water Molecules ◽  
Natural Polymers

The organization of water molecules adsorbed onto cellulose and the supramolecular hydrated structure of microfibril aggregates represents, still today, one of the open and complex questions in the physical chemistry of natural polymers.

Aluminiumphosphate mit nichtzentrosymmetrischen Schicht- und Raumnetzstrukturen aus topologisch verwandten Motiven: 2. KAl2(PO4)2(OH)·2H2O/Aluminum Phosphates with Non-Centrosymmetric Layer- and Framework-Structures of Topologically Related Motifs: 2. KAl2(PO4)2(OH)·2H2O

1997 ◽  
Vol 52 (12) ◽  
pp. 1447-1455 ◽  
Author(s):  
Stefan Dick ◽  
Gisbert Großmann ◽  
Gisela Ohms ◽  
Manfred Müller
Keyword(s):  
Nmr Spectra ◽  
Three Dimensional ◽  
Potassium Phosphate ◽  
Mas Nmr ◽  
Water Molecules ◽  
Phosphate Solution ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Aluminum Phosphates ◽  
Phosphate Groups

Abstract KAl2(PO4)2(OH)·2H2O was obtained by the reaction of gibbsite with a potassium-phosphate solution of pH = 5.5 at 373 K. A single crystal X-ray structure analysis showed that it is an ordered, F-free K-analog of the microporous compound AIPO4-CI2 . Crystal data: orthorhombic space group P212121, a = 920.5(1), b = 970.7(2), c = 982.8(2) pm, Z = 4. The structure consists of dimeric units of AIO6 octahedra and AIO5 trigonal bipyramids, bridged by an OH and two bidentate phosphate groups. The dimers are linked by phosphate to form corrugated layers which are topologically related to the layers in KAl2(PO4)2(OH)·4H2O and minyulite. The layers are connected by Al-O-P and hydrogen bonds to a three dimensional framework structure with K ions in channel-like cavities. A neutron powder scattering experiment with KAl2(PO4)2(OD)·2D2O showed that the bridging OD group and only one D of each water molecule are involved in hydrogen bonding.31P MAS NMR spectra show two isotropic lines at δiso = -6.9 and -18,7 ppm of the intensity ratio 1:1 and confirm the presence of two crystallographically independent P atoms in the unit cell. In the 1H MAS NMR spectra the water molecules and the bridging OH group show signals at 5.9 and 1.1 ppm, respectively.

51V and 133Cs MAS NMR Investigation of Crystalline Trivanadate and Hexavanadate Phases.

2006 ◽  
Vol 984 ◽  
Author(s):  
Olivier Durupthy ◽  
Jocelyne Maquet ◽  
Nathalie Steunou ◽  
Christian Bonhomme ◽  
Jacques Livage
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Local Environment ◽  
Vanadium Oxides ◽  
Mas Nmr ◽  
Water Molecules ◽  
Cesium Ions ◽  
Nmr Characterization ◽  
Interlamellar Space

AbstractA complete solid state NMR characterization of the vanadium oxides Cs[V3O8] and Cs2[V6O16].0.7H2O is proposed. We used 51V and 133Cs MAS NMR to investigate the local environment of cesium and vanadium nuclei and 2D 1H- 133Cs CP MAS HETCOR experiments to explore the connectivities between cesium ions and water molecules in the interlamellar space.

Effect of Adsorbed Water Molecules on the Surface Acidity of Niobium and Tantalum Oxides Studied by MAS NMR

2021 ◽  
Author(s):  
Xin Chen ◽  
Daofeng Huang ◽  
Lulu He ◽  
Li Zhang ◽  
Yuanhang Ren ◽  
...  
Keyword(s):  
Surface Acidity ◽  
Adsorbed Water ◽  
Mas Nmr ◽  
Water Molecules
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