scholarly journals Photocrystallography

2007 ◽  
Vol 64 (1) ◽  
pp. 259-271 ◽  
Author(s):  
Jacqueline M. Cole
Keyword(s):  
Structural Changes ◽  
Three Dimensional ◽  
Research Area ◽  
Active Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Future Possibility ◽  
New Research ◽  
Exciting Area

This review describes the development and application of a new crystallographic technique that is starting to enable the three-dimensional structural determination of molecules in their photo-activated states. So called `photocrystallography' has wide applicability, particularly in the currently exciting area of photonics, and a discussion of this applied potential is put into context in this article. Studies are classified into four groups: photo-structural changes that are (i) irreversible; (ii) long-lived but reversible under certain conditions; (iii) transient with photo-active lifetimes of the order of microseconds; (iv) very short lived, existing at the nanosecond or even picosecond level. As photo-structural changes relative to the `ground state' can be subtle, this article necessarily concentrates on small-molecule single-crystal X-ray diffraction given that high atomic resolution is possible. That said, where it is pertinent, references are also made to related major advances in photo-induced macromolecular crystallography. The review concludes with an outlook on this new research area, including the future possibility of studying even more ephemeral, femtosecond-lived, photo-active species.

Structure determination of a partially ordered layered silicate material with an NMR crystallography approach

2017 ◽  
Vol 73 (3) ◽  
pp. 184-190 ◽  
Author(s):  
Darren Henry Brouwer ◽  
Sylvian Cadars ◽  
Kathryn Hotke ◽  
Jared Van Huizen ◽  
Nicholas Van Huizen
Keyword(s):  
Nmr Spectroscopy ◽  
Structure Determination ◽  
Three Dimensional ◽  
Layered Silicate ◽  
Silicate Layer ◽  
Silicate Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Crystallography

Structure determination of layered materials can present challenges for conventional diffraction methods due to the fact that such materials often lack full three-dimensional periodicity since adjacent layers may not stack in an orderly and regular fashion. In such cases, NMR crystallography strategies involving a combination of solid-state NMR spectroscopy, powder X-ray diffraction, and computational chemistry methods can often reveal structural details that cannot be acquired from diffraction alone. We present here the structure determination of a surfactant-templated layered silicate material that lacks full three-dimensional crystallinity using such an NMR crystallography approach. Through a combination of powder X-ray diffraction and advanced 29Si solid-state NMR spectroscopy, it is revealed that the structure of the silicate layer of this layered silicate material templated with cetyltrimethylammonium surfactant cations is isostructural with the silicate layer of a previously reported material referred to as ilerite, octosilicate, or RUB-18. High-field 1H NMR spectroscopy reveals differences between the materials in terms of the ordering of silanol groups on the surfaces of the layers, as well as the contents of the inter-layer space.

Experimental Method of Determination of Structural Correlations in Surface Layers of Oxide Glass

1990 ◽  
Vol 216 ◽  
Author(s):  
Zenon BochyŃski
Keyword(s):  
Structural Changes ◽  
Lattice Models ◽  
Molecular Size ◽  
Oxide Glass ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
The Real ◽  
Inorganic Glasses

ABSTRACTA new method of X-ray diffraction analysis of structural inhomogeneities in the quartz/Si02/n based inorganic glasses is presented. The method enables the determination of structural changes occuring in the real nodal lattice in the regions of 10…20 Å or more as well as substructural changes in the regions 5…15 Å comparable to the molecular size of SiO2…SiO4. In consequence these changes can be correlated with approximate nodal lattice models of different degree of ordering. The applied method provided the possibility of constructing structural models of nodal lattices describing the surface and inner layers of the real glasses, changes in the local inhomogeneities as well as boundaries in water-gel associates.

A determination of structural evolution during the processing of glycol-based, sol-gel derived ceramics through the study of ferrimagnetic interactions

2007 ◽  
Vol 22 (11) ◽  
pp. 3152-3157 ◽  
Author(s):  
Edward J. Donahue ◽  
Michael Ng ◽  
Patrick Li
Keyword(s):  
Thermogravimetric Analysis ◽  
Structural Changes ◽  
Sol Gel ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
Straight Chain ◽  
X Ray ◽  
Decomposition Pathway ◽  
Ferrimagnetic Ordering

This work studies the chemical and structural changes that occur in sols upon heating to form ceramics. Ferrimagnetic Y3Fe5O12 (YIG) was chosen because the geometric and structural constraint of ferrimagnetic interactions allow for a direct measurement of the degree of well-defined structure present within the sol at various stages of development. Glycolate sols of 8% mol total metal were prepared using Y(NO3)3 and Fe(NO3)3 hydrates in stoichiometric ratios. Terminal straight-chain diols were used, ranging from 1,2-ethanediol to 1,6-hexanediol. The temperatures at which mass change occurred during heating were determined by thermogravimetric analysis. Samples were heated to these temperatures and examined by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction, and magnetometry to determine chemical, structural, and magnetic changes. Ferrimagnetic ordering was present after the first heating step. Defined structure, determined by x-ray, occurred in the penultimate step. Analysis of FTIR spectra, in conjunction with the results of thermogravimetric analysis, revealed a predictable decomposition pathway.

scholarly journals Three-dimensional electron diffraction for porous crystalline materials: structural determination and beyond

2021 ◽  
Author(s):  
Zhehao Huang ◽  
Tom Willhammar ◽  
Xiaodong Zou
Keyword(s):  
Electron Diffraction ◽  
Three Dimensional ◽  
Structural Determination ◽  
New Materials ◽  
Dimensional Electron ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Structural Details

Three-dimensional electron diffraction is a powerful tool for accurate structure determination of zeolite, MOF, and COF crystals that are too small for X-ray diffraction. By revealing the structural details, the properties of the materials can be understood, and new materials and applications can be designed.

scholarly journals DETERMINATION OF PIROCARBON MATRIX CHARACTERISTICS IN CARBON/CARBON COMPOSITES

2021 ◽  
Vol 64 (5) ◽  
pp. 44-49
Author(s):  
Maria V. Papkova ◽  
Sergei V. Tashchilov ◽  
Ilya V. Magnitsky ◽  
Alexander E. Dvoretsky
Keyword(s):  
Structural Characteristics ◽  
Three Dimensional ◽  
Carbon Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Extinction Angle ◽  
Parallel Layer ◽  
The Matrix ◽  
Average Size

One of the methods of carbon/carbon composites (C/C composites) production is the deposition of a pyrocarbon (pyC) matrix in a porous preform. The investigation of the pyC matrix characteristics is based on the optical anisotropy with determination of the extinction angle Ae and X-ray diffraction determination of the interplanar spacing d002, crystallite size in the direction of stacking of graphite layers Lc and average size of graphite planes parallel layer in crystallites La. In this study, three previously produced by the thermal gradient method with different parameters specimens of C/C composites were investigated by optical microscopy and X-ray diffraction methods. The studied specimens have a different type of a texture and different structural characteristics of the pyC matrix. Extinction angle Ae for specimen 1, specimen 2 and 3 was 5°, 19° and 41°, respectively. The range of the extinction angle for the pyC matrix is wider than that presented in literature. And according to the classification of pyC the matrix of specimen 1, specimen 2 and 3 is dark laminar pyC, rough laminar pyC and highly textured pyC. For specimen 2 the largest d002 equal to 0.3476 nm was observed. The lowest degree of three-dimensional ordering relative other specimens was for the specimen 2 with rough laminar pyC matrix. The highest degree of three-dimensional ordering was for the specimen 3 with highly textured pyC matrix. However, there is no direct relationship between the textural and structural characteristics of the pyC matrix. Therefore, the study of the pyC matrix should be based on optical and X-ray diffraction methods.

scholarly journals Multilayer 3D Chirality and Its Synthetic Assembly

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Guanzhao Wu ◽  
Yangxue Liu ◽  
Zhen Yang ◽  
Nandakumar Katakam ◽  
Hossein Rouh ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Research Area ◽  
Enantiomeric Purity ◽  
Chiral Hplc ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sandwich Type ◽  
Material Sciences ◽  
New Research ◽  
Parallel Fashion

3D chirality of sandwich type of organic molecules has been discovered. The key element of this chirality is characterized by three layers of structures that are arranged nearly in parallel fashion with one on top and one down from the center plane. Individual enantiomers of these molecules have been fully characterized by spectroscopies with their enantiomeric purity measured by chiral HPLC. The absolute configuration was unambiguously assigned by X-ray diffraction analysis. This is the first multilayer 3D chirality reported and is anticipated to lead to a new research area of asymmetric synthesis and catalysis and to have a broad impact on chemical, medicinal, and material sciences in future.

scholarly journals History of protein crystallography in China

2007 ◽  
Vol 362 (1482) ◽  
pp. 1035-1042 ◽  
Author(s):  
Zihe Rao
Keyword(s):  
Protein Crystallography ◽  
Three Dimensional ◽  
Porcine Insulin ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Subsequent Determination ◽  
History Of

China has a strong background in X-ray crystallography dating back to the 1920s. Protein crystallography research in China was first developed following the successful synthesis of insulin in China in 1966. The subsequent determination of the three-dimensional structure of porcine insulin made China one of the few countries which could determine macromolecular structures by X-ray diffraction methods in the late 1960s and early 1970s. After a slow period during the 1970s and 1980s, protein crystallography in China has reached a new climax with a number of outstanding accomplishments. Here, I review the history and progress of protein crystallography in China and detail some of the recent research highlights, including the crystal structures of two membrane proteins as well as the structural genomics initiative in China.

A fast methodology to determine the characteristics of thousands of grains using three-dimensional X-ray diffraction. I. Overlapping diffraction peaks and parameters of the experimental setup

2012 ◽  
Vol 45 (4) ◽  
pp. 693-704 ◽  
Author(s):  
Hemant Sharma ◽  
Richard M. Huizenga ◽  
S. Erik Offerman
Keyword(s):  
Data Analysis ◽  
Three Dimensional ◽  
Experimental Setup ◽  
Centre Of Mass ◽  
X Ray Diffraction ◽  
X Ray ◽  
Overlapping Peaks ◽  
Diffraction Peaks ◽  
Mass Position

A data-analysis methodology is presented for the characterization of three-dimensional microstructures of polycrystalline materials from data acquired using three-dimensional X-ray diffraction (3DXRD). The method is developed for 3DXRD microscopy using a far-field detector and yields information about the centre-of-mass position, crystallographic orientation, volume and strain state for thousands of grains. This first part deals with pre-processing of the diffraction data for input into the algorithms presented in the second part [Sharma, Huizenga & Offerman (2012).J. Appl. Cryst.45, 705–718] for determination of the grain characteristics. An algorithm is presented for accurate identification of overlapping diffraction peaks from X-ray diffraction images, which has been an issue limiting the accuracy of experiments of this type. The algorithm works in two stages, namely the identification of overlapping peaks using a seeded watershed algorithm, and then the fitting of the peaks with a pseudo-Voigt shape function to yield an accurate centre-of-mass position and integrated intensity for the peaks. Regions consisting of up to six overlapping peaks can be successfully fitted. Two simulations and an experiment are used to verify the results of the algorithms. An example of the processing of diffraction images acquired in a 3DXRD experiment with a sample consisting of more than 1600 grains is shown. Furthermore, a procedure for the determination of the parameters of the experimental setup (global parameters) without the need for a calibration sample is presented and validated using simulations. This is immensely beneficial for simplifying experiments and the subsequent data analysis.

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