Syntheses, Crystal Structures, and the Phase Transformation of Octacyanometallate-Based LnIII-WV Bimetallic Assemblies with Two-Dimensional Corrugated Layers

2010 ◽  
Vol 2010 (23) ◽  
pp. 3610-3614 ◽  
Author(s):  
Ai-Hua Yuan ◽  
Peter D. Southon ◽  
David J. Price ◽  
Cameron J. Kepert ◽  
Hu Zhou ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Crystal Structures ◽  
Two Dimensional

scholarly journals Symmetry of diffraction patterns of two-dimensional crystal structures

2021 ◽  
pp. 113336
Author(s):  
Tatiana Latychevskaia ◽  
Recep Zan ◽  
Sergey Morozov ◽  
Kostya S. Novoselov
Keyword(s):  
Crystal Structures ◽  
Two Dimensional ◽  
Diffraction Patterns ◽  
Dimensional Crystal

Two-Dimensional Transient Heat Transfer Model for High-Temperature Laser-Scanning Confocal Microscopy

2021 ◽  
Author(s):  
Dasith Liyanage ◽  
Suk-Chun Moon ◽  
Ajith S. Jayasekare ◽  
Abheek Basu ◽  
Madeleine Du Toit ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
High Temperature ◽  
Laser Scanning ◽  
Laser Scanning Confocal Microscopy ◽  
Transfer Model ◽  
Two Dimensional ◽  
Scanning Confocal Microscopy ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract High-temperature laser-scanning confocal microscopy (HT-LSCM) has proven to be an excellent experimental technique through in-situ observations of high temperature phase transformation to study kinetics and morphology using thin disk steel specimens. A 1.0 kW halogen lamp, within the elliptical cavity of the HT-LSCM furnace radiates heat and imposes a non-linear temperature profile across the radius of the steel sample. This local temperature profile when exposed at the solid/liquid interface determines the kinetics of solidification and phase transformation morphology. A two-dimensional numerical heat transfer model for both isothermal and transient conditions is developed for a concentrically solidifying sample. The model can accommodate solid/liquid interface velocity as an input parameter under concentric solidification with cooling rates up to 100 K/min. The model is validated against a commercial finite element analysis software package, Strand7, and optimized with experimental data obtained under near-to equilibrium conditions. The validated model can then be used to define the temperature landscape under transient heat transfer conditions.

Dimorphic ThNi2P2 with BaCu2S2 and CaBe2Ge2 Type Structure

1994 ◽  
Vol 49 (8) ◽  
pp. 1074-1080 ◽  
Author(s):  
Jörg H. Albering ◽  
Wolfgang Jeitschko
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Crystal Structures ◽  
Type Structure ◽  
Variable Parameters ◽  
Higher Symmetry ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
High Temperature Form

Two modifications of ThNi2P2 were prepared in a tin flux at 850 °C (α-ThNi2P2) and 1000 °C (β-ThNi2P2). The crystal structures of both modifications were refined from single­crystal X-ray data. α-ThNi2P2 (BaCu2S2 type structure): Pnma. a = 819.69(5), b = 394.28(3), c = 981.54(7) pm. R = 0.028 for 32 variables and 654 structure factors: β-ThNi2P2 (CaBe2Ge2 type structure): P4/nmm, a = 408.5(1), c = 908.0(3) pm, R = 0.033 for 15 variable parameters and 261 F values. Although the two structures are closely related, they can be transformed into each other only by a reconstructive phase transformation. The differences and similari­ties of the two structures are discussed. The high temperature form has higher symmetry, a smaller number of variable positional parameters, and a tendency for higher coordination numbers.

scholarly journals Pt2Tl Building Blocks for Two-Dimensional Extended Solids: Synthesis, Crystal Structures, and Luminescence

2017 ◽  
Vol 17 (8) ◽  
pp. 4336-4346 ◽  
Author(s):  
Sara Fuertes ◽  
Andrés J. Chueca ◽  
Antonio Martín ◽  
Violeta Sicilia
Keyword(s):  
Crystal Structures ◽  
Building Blocks ◽  
Two Dimensional ◽  
Extended Solids

scholarly journals Crystal structures of 4-chloropyridine-2-carbonitrile and 6-chloropyridine-2-carbonitrile exhibit different intermolecular π-stacking, C—H...Nnitrileand C—H...Npyridineinteractions

2015 ◽  
Vol 71 (7) ◽  
pp. 852-856 ◽  
Author(s):  
Matthew J. Montgomery ◽  
Thomas J. O'Connor ◽  
Joseph M. Tanski
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Pyridine Ring ◽  
Nitrile Group ◽  
Two Dimensional ◽  
One Dimensional ◽  
Face To Face ◽  
Π Stacking

The two title compounds are isomers of C6H3ClN2containing a pyridine ring, a nitrile group, and a chloro substituent. The molecules of each compound pack together in the solid state with offset face-to-face π-stacking, and intermolecular C—H...Nnitrileand C—H...Npyridineinteractions. 4-Chloropyridine-2-carbonitrile, (I), exhibits pairwise centrosymmetric head-to-head C—H...Nnitrileand C—H...Npyridineinteractions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The intermolecular packing of the isomeric 6-chloropyridine-2-carbonitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C—H...Nnitrileand C—H...Npyridineinteractions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between molecules with alternating orientations of the chloro and nitrile substituents.

Isomorphous rare-earth bis[bis(2,6-diisopropylphenyl)phosphate] complexes and their self-assembly into two-dimensional frameworks by intramolecular hydrogen bonds

2017 ◽  
Vol 73 (10) ◽  
pp. 820-827 ◽  
Author(s):  
Mikhail E. Minyaev ◽  
Ilya E. Nifant'ev ◽  
Alexander N. Tavtorkin ◽  
Sof'ya A. Korchagina ◽  
Shadana Sh. Zeynalova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Self Assembly ◽  
Pentagonal Bipyramid ◽  
Crystallographic Axis ◽  
Nitrate Anion ◽  
Two Dimensional ◽  
Space Group ◽  
Intramolecular Hydrogen

The crystal structures of rare-earth diaryl- or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]chloridotetrakis(methanol-κO)neodymium methanol disolvate, [Nd(C24H34O4P)Cl(CH4O)4]·2CH3OH, (1), and of the lutetium, [Lu(C24H34O4P)Cl(CH4O)4]·2CH3OH, (2), and yttrium, [Y(C24H34O4P)Cl(CH4O)4]·2CH3OH, (3), analogues have been obtained by reactions between lithium bis(2,6-diisopropylphenyl)phosphate and LnCl3(H2O)6 (in a 2:1 ratio) in methanol. Compounds (1)–(3) crystallize in the C2/c space group. Their crystal structures are isomorphous. The molecule possesses C 2 symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6-diisopropylphenyl)phosphate ligands all display a κ1 O-monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O2P(O-2,6-iPr2C6H3)2}2Cl(CH3OH)4] molecular unit exhibits two intramolecular O—H...O hydrogen bonds, forming six-membered rings, and two intramolecular O—H...Cl interactions, forming four-membered rings. Intermolecular O—H...O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two-dimensional hydrogen-bond network. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]tetrakis(methanol-κO)(nitrato-κ2 O,O′)neodymium methanol disolvate, [Nd(C24H34O4P)(NO3)(CH4O)4]·2CH3OH, (4), have been obtained in an analogous manner from NdCl3(H2O)6. Compound (4) also crystalizes in the C2/c space group. Its crystal structure is similar to those of (1)–(3). The κ2 O,O′-bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CNNd = 8). Unlike (1)–(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO3 − ligand. The structure of (4) displays intra- and intermolecular O—H...O hydrogen bonds similar to those in (1)–(3). Compounds (1)–(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare-earth complexes.

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network

2021 ◽  
Vol 77 (2) ◽  
pp. 211-218
Author(s):  
Ivica Cvrtila ◽  
Vladimir Stilinović
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
The Other ◽  
Two Dimensional ◽  
Structural Motifs ◽  
Supramolecular Isomerism ◽  
Other Hand ◽  
Π Stacking ◽  
Hydrogen Bonded

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2− and [H3Fe(CN)6]− anions. The layers are further connected by hydrogen bonds, as well as through π–π stacking of phenazine moieties. Aside from the identical 2D hydrogen-bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen-bonded trimers and hexamers within the hydrogen-bonded networks, which leads to different packing of the hydrogen-bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry-independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge-assisted hydrogen bonding or π-stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism.

scholarly journals Database of Two-Dimensional Hybrid Perovskite Materials: Open-Access Collection of Crystal Structures, Band Gaps, and Atomic Partial Charges Predicted by Machine Learning

2020 ◽  
Vol 32 (17) ◽  
pp. 7383-7388 ◽  
Author(s):  
Ekaterina I. Marchenko ◽  
Sergey A. Fateev ◽  
Andrey A. Petrov ◽  
Vadim V. Korolev ◽  
Artem Mitrofanov ◽  
...  
Keyword(s):  
Machine Learning ◽  
Open Access ◽  
Crystal Structures ◽  
Band Gaps ◽  
Two Dimensional ◽  
Perovskite Materials ◽  
Hybrid Perovskite ◽  
Partial Charges

scholarly journals Phase transformation in two-dimensional covalent organic frameworks under compressive loading

2018 ◽  
Vol 20 (46) ◽  
pp. 29462-29471 ◽  
Author(s):  
Jin Zhang
Keyword(s):  
Phase Transformation ◽  
Material Properties ◽  
Compressive Loading ◽  
Two Dimensional ◽  
Covalent Organic Frameworks

We report a novel phase transformation in 2D COFs under compression, which greatly alters the material properties of 2D COFs.

Sign in / Sign up

Export Citation Format

Share Document