scholarly journals Efficient Exfoliation of Layered Double Hydroxides; Effect of Cationic Ratio, Hydration State, Anions and Their Orientations

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 346 ◽  
Author(s):  
Jayakumar Karthikeyan ◽  
Helmer Fjellvåg ◽  
Silje Bundli ◽  
Anja Olafsen Sjåstad
Keyword(s):  
Layered Double Hydroxides ◽  
Particle Morphology ◽  
Clear Correlation ◽  
Water Molecules ◽  
Nitrate Anion ◽  
Hydration State ◽  
Double Hydroxides ◽  
Charge Balancing ◽  
Nitrate Anions ◽  
Anion Type

The exfoliation ability of nitrate based Mg1−xAlx(OH)2(NO3)x·mH2O layered double hydroxides (Mg-Al LDH) in formamide into single or multilayer nanosheets depends strongly on nitrate anion orientation and layer charge. Our systematic studies used materials that were likely to disclose differences with respect to anion type and their concentrations in the interlayer gallery. We assured to avoid any carbonate incorporation into the galleries for nitrate, chloride, iodide, and sulfate based Mg-Al LDHs. Furthermore, the comparative exfoliation experiments were conducted for fully hydrated samples with as similar particle morphology as possible. The exfoliation of nitrate Mg-Al LDH is far superior to similar clays with carbonate, sulfate, chloride, or iodide as charge balancing anions. Quantitative analysis of exfoliation yield for pre-treated, fully hydrated samples, shows an optimum composition for exfoliation into single nanosheets of around x ≈ 0.25, while double or triple layered sheets are encountered for other x-values. We observe a clear correlation between the expansion of the interlayer gallery due to progressing tilts of nitrate anions and water molecules out of the horizontal interlayer plane, suspension turbidity, and degree of exfoliation. The established correlations extends to nitrate Ni-Al LDH materials. We finally claim that morphology is a dominating parameter, with house-of-card morphology particles exfoliation far less than platelet-like particles. Hence, hydrothermal treatment may be favorable to enhance exfoliation yields.

scholarly journals Bis{2-[(pyridin-2-yl)methylideneamino]benzoato-κ3N,N′,O}chromium(III) nitrate monohydrate

2014 ◽  
Vol 70 (4) ◽  
pp. m136-m136 ◽  
Author(s):  
Elena A. Buvaylo ◽  
Vladimir N. Kokozay ◽  
Olga Yu. Vassilyeva ◽  
Brian W. Skelton
Keyword(s):  
Site Occupancy ◽  
Complex Salt ◽  
Dihedral Angles ◽  
Water Molecules ◽  
Nitrate Anion ◽  
Schiff Base Ligands ◽  
Salt Hydrate ◽  
Solvent Water ◽  
Benzene Rings ◽  
Nitrate Anions

The title complex salt hydrate, [Cr(C13H9N2O2)2]NO3·H2O, comprises discrete cations, nitrate anions and solvent water molecules. The CrIIIatom is octahedrally coordinated by two anionic Schiff base ligands with the O atoms beingcis. The two ligands differ significantly with dihedral angles between the pyridine and benzene rings of 4.8 (2) and 24.9 (2)°. The nitrate anion and solvent water molecule were modelled as being disordered, with the major components having site-occupancy values of 0.856 (14) and 0.727 (16), respectively. The crystal is built of alternating layers of cations and of anions plus water molecules, stacked along thecaxis.

scholarly journals Tetrakis(1,10-phenanthroline)bis(μ-pyridine-2,6-dicarboxylato)(pyridine-2,6-dicarboxylato)dicopper(II)terbium(III) nitrate tetrahydrate

2012 ◽  
Vol 68 (8) ◽  
pp. m1084-m1085
Author(s):  
Wei Zhang
Keyword(s):  
Weak Interactions ◽  
Rotation Axis ◽  
Water Molecules ◽  
Nitrate Anion ◽  
Stacking Interactions ◽  
Asymmetric Unit ◽  
Coordination Environment ◽  
Nitrate Tetrahydrate ◽  
Nitrate Anions ◽  
Phenanthroline Ligands

The asymmetric unit of the title compound, [Cu2Tb(C7H3NO4)3(C12H8N2)4]NO3·4H2O, consists of one-half of theC2-symmetric trinuclear coordination cation, one-half of theC2-symmetric nitrate anion and two water molecules. In the coordination cation, the CuIIatom is coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms from a bridging–chelating carboxylate group of the pyridine-2,6-dicarboxylate anion, completing a distorted N4O2octahedral coordination environment. The TbIIIatom, located on a twofold rotation axis, is nine-coordinated by three tridentate pyridine-2,6-dicarboxylate anions forming an N3O6donor set. The intramolecular Cu...Tb distance of 5.0592 (11) Å indicates weak interactions between the CuIIand TbIIIatoms. The coordination cations, nitrate anions and water molecules are connectedviaO—H...O hydrogen bonds into layers parallel to the (001) plane. Moreover, there are extensive π–π stacking interactions [centroid–centroid distances = 4.332 (7) and 3.878 (5) Å] between the phenanthroline ligands and between phenanthroline and pyridine-2,6-dicarboxylate ligands.

Study on the Photochromism of Ni–Al Layered Double Hydroxides Containing Nitrate Anions

2006 ◽  
Vol 2006 (14) ◽  
pp. 2831-2838 ◽  
Author(s):  
Min Wei ◽  
Xiangyu Xu ◽  
Xinrui Wang ◽  
Feng Li ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Double Hydroxides ◽  
Nitrate Anions

Molecular Dynamics Simulation of Interlayer Structure and Hydration Properties of Glycine Intercalated Layered Double Hydroxides

2011 ◽  
pp. 242-250
Author(s):  
Guo-Xiang Pan ◽  
Feng Cao ◽  
Pei-Song Tang ◽  
Hai-Feng Chen ◽  
Zhe-Ming Ni ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Layered Double Hydroxides ◽  
Interlayer Spacing ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydration Properties ◽  
Interlayer Structure ◽  
Double Hydroxides ◽  
Water Contents

Interlayer structure, hydrogen-bond, hydration and swelling properties of glycine intercalated layered double hydroxides (LDHs-Gly) were investigated with molecular dynamics (MD) methods. The results show that the interlayer spacing dc increases as hydration level increases. The computed hydration energies reach the most negative values at low water contents and change rapidly over the range 1 = NW = 6, and slowly and gradually approach the potential energy for bulk SPC water at NW > 6. But there are no local minima in the energy over the entire hydration range. This result suggests that LDHs-Gly tend to absorb water continuously in water-rich environments and enhance swelling to delaminate the hydroxide layers. The interlayers of LDHs-Gly exhibit complex hydrogen-bond network. With water content increasing, the glycine molecules progressively change their orientation from parallel to the layers to nearly perpendicular. Water molecules firstly form hydrogen-bond with M-OH layers at low water contents. While the hydroxide layers gradually get to saturation state at Nw > 3. And then water molecules continuously fill the interlayer to expand interlayer spacing.

scholarly journals Preparation of Layered Double Hydroxides toward Precisely Designed Hierarchical Organization

2019 ◽  
Vol 3 (3) ◽  
pp. 68 ◽  
Author(s):  
Rattanawadee (Ploy) Wijitwongwan ◽  
Soontaree (Grace) Intasa-ard ◽  
Makoto Ogawa
Keyword(s):  
Layered Double Hydroxides ◽  
Drug Carrier ◽  
Particle Morphology ◽  
Hierarchical Organization ◽  
Synthetic Methods ◽  
Practical Application ◽  
Preparation Methods ◽  
Wide Range ◽  
Varied Composition ◽  
Double Hydroxides

Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities for a wide range of materials’ applications including adsorbent, catalyst and its support, ceramic precursor, and drug carrier. In order to satisfy the requirements for the detailed characterization and the practical application, the preparation of LDHs with varied composition and particle morphology has been examined extensively. The versatility of the preparation methods led LDHs with varied composition and micro/macroscopic morphology, which makes the application of LDHs more realistic. In the present review article, synthetic methods of LDHs are overviewed in order to highlight the present status of the LDHs for practical application.

Influences of Cation Ratio, Anion Type, and Water Content on Polytypism of Layered Double Hydroxides

2018 ◽  
Vol 57 (12) ◽  
pp. 7299-7313 ◽  
Author(s):  
Meng Chen ◽  
Runliang Zhu ◽  
Xiancai Lu ◽  
Jianxi Zhu ◽  
Hongping He
Keyword(s):  
Water Content ◽  
Layered Double Hydroxides ◽  
Double Hydroxides ◽  
Anion Type ◽  
Cation Ratio

Thermal evolution of Mg–Al and Ni–Al layered double hydroxides: the structure of the dehydrated phase

2016 ◽  
Vol 72 (6) ◽  
pp. 651-659 ◽  
Author(s):  
Svetlana Cherepanova ◽  
Natalya Leont'eva ◽  
Vladimir Drozdov ◽  
Vladimir Doronin
Keyword(s):  
Layered Double Hydroxides ◽  
Thermal Evolution ◽  
Water Molecules ◽  
Initial Structure ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Turbostratic Disorder ◽  
Diffraction Patterns ◽  
Double Hydroxides

Simulation of X-ray diffraction patterns on the basis of the models of one-dimensional disordered crystals was used to investigate the structure of the dehydrated phase produced by dehydration of Mg–Al and Ni–Al layered double hydroxides at a temperature of ∼473–498 K. It was found that the removal of water molecules transforms the initial structure, which is a mixture of 3R1and 2H1polytypes, into a structure that comprises preferentially fragments of 3R2and 1Hpolytypes and has some turbostratic disorder.

scholarly journals Hydrotalcites in Construction Materials

2020 ◽  
Vol 10 (22) ◽  
pp. 7989
Author(s):  
Anna-Marie Lauermannová ◽  
Iva Paterová ◽  
Jan Patera ◽  
Kryštof Skrbek ◽  
Ondřej Jankovský ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Radioactive Waste ◽  
Construction Industry ◽  
Layered Double Hydroxides ◽  
Building Materials ◽  
Construction Materials ◽  
Water Molecules ◽  
Wide Range ◽  
Waste Repository ◽  
Double Hydroxides

Hydrotalcites are layered double hydroxides displaying a variety of stoichiometry caused by the different arrangement of the stacking of the layers, ordering of the metal cations, as well as the arrangement of anions and water molecules, in the interlayer galleries. The compounds of the hydrotalcite group show a wide range of the possible applications due to their specific properties, such as their large surface area, ion exchange ability, the insolubility in water and most of the organic sorbents, and others. Affordability, wide possibilities of manufacturing, and presence of sufficient natural deposits make hydrotalcites potentially very useful for the construction industry, as either a building material itself or an additive in mortars, concrete or in polymers composites used in constructions. Similar possible application of such material is in leakage control in a radioactive waste repository. The effect of use of these materials for ion exchange, anti-corrosion protection, radioactive ions containment, and similar purposes in building materials is examined in this review.

scholarly journals Crystal structure of hydroxy scandium nitrate chloride

2019 ◽  
Vol 75 (5) ◽  
pp. 540-542 ◽  
Author(s):  
Jeremiah Sears ◽  
Roger Cramer ◽  
Timothy Boyle
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Coordination Polyhedron ◽  
Three Dimensional ◽  
Outer Sphere ◽  
Water Molecules ◽  
Nitrate Anion ◽  
Inversion Symmetry ◽  
Dimensional Network ◽  
Charge Balancing

Each Sc3+ ion in the title salt, di-μ-hydroxido-bis[triaqua(nitrato-κ2 O,O′)scandium(III)] dichloride, [Sc2(NO3)2(OH)2(H2O)6]Cl2, is coordinated by a nitrate anion, two hydroxide ions and three water molecules to generate a distorted pentagonal–bipyramidal ScO7 coordination polyhedron. The complete {[(NO3)(μ-OH)Sc(H2O)3]2}2+ ion is generated by crystallographic inversion symmetry. The nitrate anion binds in a bidentate fashion whereas the hydroxide ions are bridged between two Sc centers. Two charge-balancing Cl− ions are located in the outer sphere. In the extended structure, O—H...O and O—H...Cl hydrogen bonds connect the components into a three-dimensional network.

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