3,4:9,10-Perylenetetracarboxylic dianhydride (PTCDA) by electron crystallography

1999 ◽  
Vol 55 (1) ◽  
pp. 123-130 ◽  
Author(s):  
Tetsuya Ogawa ◽  
Kiyoshi Kuwamoto ◽  
Seiji Isoda ◽  
Takashi Kobayashi ◽  
Norbert Karl
Keyword(s):  
Crystal Structure Data ◽  
Molecular Axis ◽  
Imaging Plate ◽  
Lattice Plane ◽  
X Ray Diffraction ◽  
Electron Crystallography ◽  
Molecular Plane ◽  
X Ray ◽  
Benzene Rings ◽  
Packing Scheme

The crystal structures of the α and β modifications of PTCDA were analyzed as projected structures along the a axes by electron crystallography using an imaging plate. The results for the α modification agree well with the sheet-and-stack structure obtained by X-ray diffraction by M. L. Kaplan et al. (private communication, full set of crystal structure data). Projected onto the (102) plane, which is parallel to the molecular sheets, the long molecular axis makes an angle of 42° with the b axis and the hexagonal benzene rings appear slightly elongated, indicating a slight inclination of the molecular plane from the (102) lattice plane. For the β modification, it was concluded that the molecules are aligned in a herringbone packing scheme on the (102) plane similar to that of the α modification, but with a slightly different angle of the long molecular axis with the b axis (38°).

scholarly journals Relation between photochromic properties and molecular structures in salicylideneaniline crystals

2012 ◽  
Vol 68 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Kohei Johmoto ◽  
Takashi Ishida ◽  
Akiko Sekine ◽  
Hidehiro Uekusa ◽  
Yuji Ohashi
Keyword(s):  
Dihedral Angle ◽  
Steric Hindrance ◽  
Molecular Structures ◽  
Dihedral Angles ◽  
Clear Correlation ◽  
X Ray Diffraction ◽  
Photochromic Properties ◽  
X Ray ◽  
Benzene Rings ◽  
The Relationship

The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

scholarly journals Lattice-plane bending angle modulation of Mg-doped GaN homoepitaxial layer observed by X-ray diffraction topography

CrystEngComm ◽  
2019 ◽  
Vol 21 (14) ◽  
pp. 2281-2285
Author(s):  
Jaemyung Kim ◽  
Okkyun Seo ◽  
Chulho Song ◽  
Satoshi Hiroi ◽  
Yanna Chen ◽  
...  
Keyword(s):  
Lattice Plane ◽  
X Ray Diffraction ◽  
Bending Angle ◽  
X Ray ◽  
Angle Modulation ◽  
Plane Bending ◽  
Homoepitaxial Layers ◽  
Mg Doped

We have studied the lattice-plane modulation of Mg-doped GaN homoepitaxial layers by X-ray diffraction topography.

The location of p-dichlorobenzene in a single crystal of zeolite H-ZSM-5 at high sorbate loading

1996 ◽  
Vol 52 (1) ◽  
pp. 140-144 ◽  
Author(s):  
H. van Koningsveld ◽  
J. C. Jansen ◽  
H. van Bekkum
Keyword(s):  
Single Crystal ◽  
Cross Sections ◽  
Unit Cell ◽  
Molecular Axis ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Elliptical Cross ◽  
X Ray ◽  
Structural Aspects

The crystal structure of a high-loaded complex of H-ZSM-5 with eight molecules of p-dichlorobenzene per unit cell has been solved by single-crystal X-ray diffraction. The orthorhombic space group P212121 with a = 20.102 (6), b = 19.797 (9), c = 13.436 (3) Å and V = 5347 (3) Å3 has four Si23.92Al0.08O48.2C6H4Cl2 units per unit cell. Dx = 2.164 Mg m−3, λ(MoKα) = 0.71073 Å and μ(Mo Kα) = 0.876 mm−1. The final R(wR) = 0.046 (0.039), w = 1/σ 2(F), for 6090 observed reflections with I > 1.0σ(I) measured at 293 K. The straight channel parallel to [010] is slightly corrugated. The elliptical cross sections have limiting apertures of 6.0 × 4.9 Å (r oxygen = 1.35 Å). The sinusoidal channel parallel to [100] is elliptical with major and minor axes of 6.1 × 4.8 Å, respectively. One of the two independent p-dichlorobenzene molecule lies at the intersection of the straight and sinusoidal channels with its long molecular axis almost parallel to (100) and deviating ~8° from [010]. The second p-dichlorobenzene molecule is in the sinusoidal channel. Its long molecular axis deviates almost 7° from [100] and is practically parallel to (010). The structural aspects are in all details comparable to those in the high-loaded H-ZSM-5/p-xylene complex [van Koningsveld, Tuinstra, van Bekkum & Jansen (1989). Acta Cryst. B45, 423–431] , except for the main interaction forces between the p-dichlorobenzene molecules at the channel intersection.

scholarly journals Si wafers having one- and two-dimensionally curved (111) planes examined by X-ray diffraction

2006 ◽  
Vol 39 (3) ◽  
pp. 443-445 ◽  
Author(s):  
Hiroshi Okuda ◽  
Kazuo Nakajima ◽  
Kozo Fujiwara ◽  
Shojiro Ochiai
Keyword(s):  
Elevated Temperatures ◽  
Peak Position ◽  
Curved Surface ◽  
Lattice Plane ◽  
X Ray Diffraction ◽  
Diffraction Scattering ◽  
X Ray ◽  
Si Wafer

Si (111) wafers deformed at elevated temperatures into cylindrical or hemispherical shapes have been examined by X-ray diffraction. Well defined 333 peaks shifted with in-plane distance from the centre of the wafer as determined by ω scans. The shift of the peak position agreed with the curvature of the Si wafer, suggesting that the Si (111) lattice plane can be designed on an arbitrarily curved surface by this method. These crystals have potential for innovative applications in X-ray instrumentation, for both diffraction/scattering and spectroscopy.

Accurate charge densities from powder X-ray diffraction – a new version of the Aarhus vacuum imaging-plate diffractometer

2017 ◽  
Vol 73 (4) ◽  
pp. 521-530 ◽  
Author(s):  
Kasper Tolborg ◽  
Mads R. V. Jørgensen ◽  
Sebastian Christensen ◽  
Hidetaka Kasai ◽  
Jacob Becker ◽  
...  
Keyword(s):  
Electron Density ◽  
High Energy ◽  
Imaging Plate ◽  
High Symmetry ◽  
X Rays ◽  
X Ray Diffraction ◽  
Core Electron ◽  
X Ray ◽  
Peak Broadening ◽  
Structure Factors

In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole–Rietveld procedure and compared withab initiocalculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.

Intergrown New Zeolite Beta Polymorphs with Interconnected 12-Ring Channels Solved by Combining Electron Crystallography and Single-Crystal X-ray Diffraction

2012 ◽  
Vol 24 (19) ◽  
pp. 3701-3706 ◽  
Author(s):  
Zheng-Bao Yu ◽  
Yu Han ◽  
Lan Zhao ◽  
Shiliang Huang ◽  
Qi-Yu Zheng ◽  
...  
Keyword(s):  
Single Crystal ◽  
Zeolite Beta ◽  
X Ray Diffraction ◽  
Electron Crystallography ◽  
X Ray

1,5-Bis(4-chlorophenyl)-3-(4-pyridyl)pentane-1,5-dione

2006 ◽  
Vol 62 (5) ◽  
pp. o1826-o1827
Author(s):  
Xiao-Yang Qiu ◽  
Wei-Sheng Liu ◽  
Hai-Liang Zhu
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Steric Effects ◽  
X Ray Diffraction ◽  
Pyridyl Group ◽  
X Ray ◽  
Compound C ◽  
Benzene Rings

The title compound, C22H17Cl2NO2, has been synthesized and characterized by single-crystal X-ray diffraction. In the crystal structure, the two benzene rings and the pyridyl group lie in a propeller arrangement around the central C atom, thereby minimizing the steric effects between these rings.

The use of an imaging plate as a detecting system in X-ray diffraction of polymers

1995 ◽  
Vol 97 (1-4) ◽  
pp. 265-268 ◽  
Author(s):  
D. Villers ◽  
C. Fougnies ◽  
L. Paternostre ◽  
C. Beumier ◽  
M. Dosière
Keyword(s):  
Imaging Plate ◽  
X Ray Diffraction ◽  
X Ray
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