Comparative study on confinement effects of graphene and graphene oxide on structure and dynamics of water

RSC Advances ◽  
2015 ◽  
Vol 5 (49) ◽  
pp. 39330-39341 ◽  
Author(s):  
Meymanat Zokaie ◽  
Masumeh Foroutan
Keyword(s):  
Hydrogen Bond ◽  
Graphene Oxide ◽  
Comparative Study ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Confinement Effects ◽  
Structure And Dynamics

A snapshot of the formation of hydrogen bond between water molecules and the hydroxyl groups of the graphene oxide. Red, blue, and green colors correspond to oxygen, hydrogen, and carbon atoms, respectively. Dashed line show the hydrogen bond.

Structures of the complexes of peanut lectin with methyl-β-galactose and N-acetyllactosamine and a comparative study of carbohydrate binding in Gal/GalNAc-specific legume lectins

1999 ◽  
Vol 55 (8) ◽  
pp. 1375-1382 ◽  
Author(s):  
R. Ravishankar ◽  
K. Suguna ◽  
A. Surolia ◽  
M. Vijayan
Keyword(s):  
Comparative Study ◽  
Water Molecules ◽  
Carbohydrate Binding ◽  
Hydroxyl Groups ◽  
Peanut Lectin ◽  
Structural Explanation ◽  
Sugar Ring ◽  
Ordered Water ◽  
The Comparative Study

The crystal structures of complexes of peanut lectin with methyl-β-galactose and N-acetyllactosamine have been determined at 2.8 and 2.7 Å, respectively. These, and the complexes involving lactose and the T-antigenic disaccharide reported previously, permit a detailed characterization of peanut-lectin–carbohydrate association and the role of water molecules therein. The water molecules in the combining site are substantially conserved in the four complexes. The role of interacting sugar hydroxyl groups, when absent, are often mimicked by ordered water molecules not only at the primary combining site, but also at the site of the second sugar ring. The similarity of peanut-lectin–sugar interactions with those in other galactose/N-acetylgalactosamine-specific lectins also extend to a substantial degree to water bridges. The comparative study provides a structural explanation for the exclusive specificity of peanut lectin for galactose at the monosaccharide level, compared with that of the other lectins for galactose as well as N-acetylgalactosamine. The complexes also provide a qualitative structural rationale for differences in the strengths of binding of peanut lectin to different sugars.

QM/MM Simulations of Organic Phosphorus Adsorption at the Diaspore-Water Interface

2019 ◽  
Author(s):  
Prasanth Babu Ganta ◽  
Oliver Kühn ◽  
Ashour Ahmed
Keyword(s):  
Interaction Energy ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Water Interface ◽  
Mineral Surfaces ◽  
Soil Mineral ◽  
Phosphorus Adsorption ◽  
Covalent Bonds ◽  
Binding Mechanisms

The phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. Related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphate onto Fe-oxide surfaces. But a molecular-level understanding for the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentate for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

High proton conductivity in a nickel(ii) complex and its hybrid membrane

2019 ◽  
Vol 48 (6) ◽  
pp. 2190-2196 ◽  
Author(s):  
Shuai-Liang Yang ◽  
Yue-Ying Yuan ◽  
Fei Ren ◽  
Chen-Xi Zhang ◽  
Qing-Lun Wang
Keyword(s):  
Hydrogen Bond ◽  
Proton Conductivity ◽  
Hybrid Membrane ◽  
Water Molecules ◽  
Hybrid Membranes ◽  
High Proton Conductivity ◽  
High Proton ◽  
Hydrogen Bond Networks

A novel 2D nickel(ii) complex (1) has been successfully synthesized using a 2,2′-bipyridyl, polycarboxylsulfonate ligand H4SBTC and Ni2+ ions. Owing to the presence of abundant water molecules, hydrogen bond networks and other protons, 1 and its hybrid membranes demonstrate high proton conductivity.

scholarly journals Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Grain Boundaries ◽  
Functional Groups ◽  
Oxygen Content ◽  
Tensile Fracture ◽  
Hydroxyl Groups ◽  
Molecular Configuration ◽  
Spatial Design ◽  
Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

Confinement effects on the structure and dynamics of polymer systems from the mesoscale to the nanoscale

2005 ◽  
Vol 43 (13) ◽  
pp. 1571-1590 ◽  
Author(s):  
M. D. Barnes ◽  
A. Mehta ◽  
P. Kumar ◽  
B. G. Sumpter ◽  
D. W. Noid
Keyword(s):  
Confinement Effects ◽  
Polymer Systems ◽  
Structure And Dynamics

Dynamics and metastable surface structure of double atomic layer of water molecules and ions at the interface between KBr(c) and water

2004 ◽  
Vol 76 (1) ◽  
pp. 115-122 ◽  
Author(s):  
K. Ichikawa ◽  
S. Sato ◽  
N. Shimomura
Keyword(s):  
Surface Structure ◽  
Vertical Motion ◽  
Atomic Layer ◽  
Water Molecules ◽  
Potassium Ions ◽  
Force Microscopy ◽  
Structure And Dynamics ◽  
Atomic Force ◽  
Bromide Ions

The metastable surface structure and dynamics of water molecules, cations, and anions at the interface between KBr(001) and water have been demonstrated from the images in situ observed in atomic resolution using atomic force microscopy. The vertical motion of potassium ions, which means their own transfer from the equilibrium sites to the upper height right on the underlying bromide ions, has been observed at the interface. They are used to be located in some steady state stabilized by their interaction with water molecules in the double atomic layer at the interface. The observed water molecules bridge two bromide ions by hydrogen bond; the water molecules are sandwiched by the potassium ions and vice versa.

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