scholarly journals Properties and interactions – melting point of tribromobenzene isomers

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Maciej Bujak ◽  
Marcin Podsiadło ◽  
Andrzej Katrusiak
Keyword(s):  
Melting Point ◽  
Single Crystals ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Close Packing ◽  
Molecular Symmetry ◽  
X Ray Diffraction ◽  
Molecular Surfaces ◽  
X Ray ◽  
The Relationship

Single crystals of isomeric 1,2,3-tribromobenzene (123TBB), 1,2,4-tribromobenzene (124TBB) and 1,3,5-tribromobenzene (135TBB) have been grown from different solvents and their structures determined by X-ray diffraction at 100, 200 and 270 K. The melting-point differences of ca 40 K between 135TBB, 123TBB and 124TBB have been correlated with the molecular symmetry and packing preferences in the crystal, as well as with the main types of intermolecular halogen interactions, i.e. Br...Br, Br...C (Br...π) and Br...H. The relationship between symmetry and melting point in Carnelley's rule has been extended to the accessibility of terminal atoms for the formation of intermolecular interactions, their occurrences and distribution, and the close packing. The electrostatic potential mapped on molecular surfaces demonstrates that in more symmetric molecules the more evenly distributed substituents are more accessible and form more optimum intermolecular interactions.

Topological characterization of electron density, electrostatic potential and intermolecular interactions of 2-nitroimidazole: an experimental and theoretical study

2016 ◽  
Vol 72 (5) ◽  
pp. 775-786 ◽  
Author(s):  
Chinnasamy Kalaiarasi ◽  
Mysore S Pavan ◽  
Poomani Kumaradhas
Keyword(s):  
Electron Density ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Theoretical Calculations ◽  
Topological Analysis ◽  
X Ray Diffraction ◽  
Topological Characterization ◽  
Data Set ◽  
X Ray ◽  
Charge Concentration

An experimental charge density distribution of 2-nitroimidazole was determined from high-resolution X-ray diffraction and the Hansen–Coppens multipole model. The 2-nitroimidazole compound was crystallized and a high-angle X-ray diffraction intensity data set has been collected at low temperature (110 K). The structure was solved and further, an aspherical multipole model refinement was performed up to octapole level; the results were used to determine the structure, bond topological and electrostatic properties of the molecule. In the crystal, the molecule exhibits a planar structure and forms weak and strong intermolecular hydrogen-bonding interactions with the neighbouring molecules. The Hirshfeld surface of the molecule was plotted, which explores different types of intermolecular interactions and their strength. The topological analysis of electron density at the bond critical points (b.c.p.) of the molecule was performed, from that the electron density ρbcp(r) and the Laplacian of electron density ∇2ρbcp(r) at the b.c.p.s of the molecule have been determined; these parameters show the charge concentration/depletion of the nitroimidazole bonds in the crystal. The electrostatic parameters like atomic charges and the dipole moment of the molecule were calculated. The electrostatic potential surface of the molecule has been plotted, and it displays a large electronegative region around the nitro group. All the experimental results were compared with the corresponding theoretical calculations performed usingCRYSTAL09.

scholarly journals The Growth and Deformation of Ice Crystals

1954 ◽  
Vol 2 (16) ◽  
pp. 397-403 ◽  
Author(s):  
J. W. Glen ◽  
M. F. Perutz
Keyword(s):  
Melting Point ◽  
Single Crystals ◽  
Basal Plane ◽  
Growth Direction ◽  
Ice Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Original Length ◽  
Break Up

AbstractX-ray diffraction photographs were taken of ice dendrites grown from water and from the vapour. In both cases [1120] was found to be the growth direction.A method of growing cylindrical single crystals of any desired orientation has been devised. Some of these crystals were extended to several times their original length. Slip took place exclusively on the basal plane. Experiments designed to locate the glide direction gave inconclusive results and suggested that, in general, crystals near the melting point can glide in any direction.Before deformation, ice crystals gave fairly sharp X-ray diffraction spots on Laue photographs. After deformation the spots are drawn out into streaks which later break up into rows of small spots. This indicates that bending of the crystals is followed by the formation of small crystallites of slightly differing orientations. Analogous effects are observed in metals.

Kyzylkumite, Ti2V3+O5(OH): new structure type, modularity and revised formula

2013 ◽  
Vol 77 (1) ◽  
pp. 33-44 ◽  
Author(s):  
T. Armbruster ◽  
B. Lazic ◽  
L. Z. Reznitsky ◽  
E. V. Sklyarov
Keyword(s):  
Structure Type ◽  
Close Packing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Atom Position ◽  
Diffraction Patterns ◽  
Modular Structures ◽  
The Relationship ◽  
Atom Position ◽  
South Baikal

AbstractThe crystal structure of kyzylkumite, ideally Ti2V3+O5 (OH), from the Sludyanka complex in South Baikal, Russia was solved and refined (including the hydrogen atom position) to an agreement index, R1, of 2.34% using X-ray diffraction data collected on a twinned crystal. Kyzylkumite crystallizes in space group P21/c, with a = 8.4787(1), b = 4.5624(1), c = 10.0330(1) Å , β = 93.174(1)º, V = 387.51(1) Å3 and Z = 4. Tivanite, TiV3+O3OH, and kyzylkumite have modular structures based on hexagonal close packing of oxygen, which are made up of rutile [TiO2] and montroseite [V3+O(OH)] slices. In tivanite the rutile:montroseite ratio is 1:1, in kyzylkumite the ratio is 2:1. The montroseite module may be replaced by the isotypic paramontroseite V4+O2 module, which produces a phase with the formula Ti2V4+O6. In the metamorphic rocks of the Sludyanka complex, vanadium can be present as V4+ and V3+ within the same mineral (e.g.in batisivite, schreyerite and berdesinskiite). Kyzylkumite has a flexible composition with respect to the M4+/M3+ ratio. The relationship between kyzylkumite and a closely related Be-bearing kyzylkumite-like mineral with an orthorhombic norbergite-type structure from Byrud mine, Norway is discussed. Both minerals have similar X-ray powder diffraction patterns.

Effect of crucible design on crystalline perfection and the enhanced optical properties of benzimidazole single crystals grown by the vertical Bridgman technique

2013 ◽  
Vol 46 (1) ◽  
pp. 276-278 ◽  
Author(s):  
B. Riscob ◽  
N. Vijayan ◽  
Mohd Shakir ◽  
M. A. Wahab ◽  
G. Bhagavannarayana
Keyword(s):  
Optical Properties ◽  
Melting Point ◽  
High Resolution ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
Bridgman Technique ◽  
X Ray ◽  
Vertical Bridgman ◽  
Double Wall

Good quality benzimidazole (BMZ) single crystals were successfully grown by the vertical Bridgman technique (VBT). The unavoidable thermal-induced structural grain boundaries formed in the normal VBT growth of these crystals with low melting point were controlled by using a double-wall ampoule. The grown single crystals were subjected to high-resolution X-ray diffraction to assess their crystallinity. The enhancement of optical properties due to the improvement in crystalline perfection is also reported.

scholarly journals Multi-Component Crystals of 2,2′-Bipyridine with Aliphatic Dicarboxylic Acids: Melting Point-Structure Relations

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1151
Author(s):  
Vhukhudo Nethanani ◽  
Eustina Batisai
Keyword(s):  
Melting Point ◽  
Dicarboxylic Acids ◽  
Conformation Analysis ◽  
Solvent Evaporation Method ◽  
X Ray Diffraction ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Aliphatic Dicarboxylic Acids ◽  
The Relationship

The aim of the study was to investigate the relationship between the melting point and the supramolecular structure of three multi-component crystals of aliphatic dicarboxylic acids with 2,2′-bipyridine and to investigate the conformations of 2,2′-bipyridine in published multi-component crystals. The crystals were prepared using the solvent evaporation method and were characterized using single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). The crystal structures were further analyzed using CrystalExplorer, and the results were correlated with the melting points. The results of the conformation analysis of the reported multi-component crystals of 2,2′-bipyridine are also presented.

Electric properties of KTiOPO4and NaTiOPO4from temperature-dependent X-ray diffraction

1999 ◽  
Vol 32 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S. Dahaoui ◽  
N. K. Hansen ◽  
J. Protas ◽  
H.-G. Krane ◽  
K. Fischer ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Single Crystals ◽  
Electrostatic Potential ◽  
Pyroelectric Coefficient ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
A Value

Single crystals of KTiOPO4(KTP) and NaTiOPO4(NaTP) show pronounced pyroelectric behaviour. In order to determine the origin of this property on an atomic scale, X-ray diffraction measurements have been carried out at several temperatures between 100 and 600 K. Modelling of the electron density and the evolution of the structure as a function of temperature has enabled the determination of values for the spontaneous polarization of the compounds and the pyroelectric coefficient of KTP, principally due to the alkaline-ion displacements with a value of 2.0 nC cm−2 K−1. Structure modifications, compared with NaTiOPO4, and the calculation of the electrostatic potential explain the anisotropic behaviour of ionic conductivity of KTP single crystals.

Multipole Analysis of the Electron Density in Topaz Using X-ray Diffraction Data

1998 ◽  
Vol 54 (6) ◽  
pp. 774-781 ◽  
Author(s):  
Yu. V. Ivanov ◽  
E. L. Belokoneva ◽  
J. Protas ◽  
N. K. Hansen ◽  
V. G. Tsirelson
Keyword(s):  
Electron Density ◽  
Critical Points ◽  
Diffraction Data ◽  
Closed Shell ◽  
Close Packing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Topological Features ◽  
Type Interaction ◽  
The Relationship

The static deformation electron density, Laplacian of the electron density and critical points in the electron density were analyzed in topaz Al2[SiO4]F2, using high-precision X-ray diffraction data. The electron deformation density, positive values of the Laplacian at (3,−1) bond critical points and the net atomic charges indicate a closed-shell-type interaction in the polyhedra. Anion valence-shell charge depletions are revealed. Maxima in the Laplacian of the electron density are displaced towards the close-packed plane owing to the mutual repulsion of the anion valence shells. The relationship between the topological features of the electron density and the close-packing concept is discussed. Shifts of the critical points from the internuclear vectors reflect the strain in the structure.

Effect of trytophan as dopant on potassium acid phthalate single crystals

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Visible Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Evaporation Technique ◽  
Absorption Studies ◽  
Evaporation Technique ◽  
Potassium Acid Phthalate ◽  
Acid Phthalate

Optically transparent single crystals of potassium acid phthalate (KAP, 0.5 g) 0.05 g and 0.1 g (1 and 2 mol %) trytophan were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X- ray diffraction analysis confirmed the changes in the lattice parameters of the doped crystals. The presence of functional groups in the crystal lattice has been determined qualitatively by FTIR analysis. Optical absorption studies revealed that the doped crystals possess very low absorption in the entire visible region. The dielectric constant has been studied as a function of frequency for the doped crystals. The thermal stability was evaluated by TG-DSC analysis.

scholarly journals Some Novel Cobalt Diphenylphosphine Complexes: Synthesis, Characterization, and Behavior in the Polymerization of 1,3-Butadiene

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4067
Author(s):  
Giovanni Ricci ◽  
Giuseppe Leone ◽  
Giorgia Zanchin ◽  
Benedetta Palucci ◽  
Alessandra Forni ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Behavior

Some novel cobalt diphenylphosphine complexes were synthesized by reacting cobalt(II) chloride with (2-methoxyethyl)diphenylphosphine, (2-methoxyphenyl)diphenylphosphine, and 2-(1,1-dimethylpropyl)-6-(diphenylphosphino)pyridine. Single crystals suitable for X-ray diffraction studies were obtained for the first two complexes, and their crystal structure was determined. The novel compounds were then used in association with methylaluminoxane (MAO) for the polymerization of 1,3-butadiene, and their behavior was compared with that exhibited in the polymerization of the same monomer by the systems CoCl2(PnPrPh2)2/MAO and CoCl2(PPh3)2/MAO. Some significant differences were observed depending on the MAO/Co ratio used, and a plausible interpretation for such a different behavior is proposed.

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