scholarly journals How many more polymorphs of ROY remain undiscovered?

2022 ◽  
Author(s):  
Gregory J. O. Beran ◽  
Isaac John Sugden ◽  
Chandler Greenwell ◽  
David Bowskill ◽  
Constantinos C. Pantelides ◽  
...  
Keyword(s):  
Organic Crystal ◽  
Crystal Forms ◽  
Current Record

With 12 crystal forms, 5-methyl-2-[(2-nitrophenyl) amino]-3-thiophenecabonitrile (a.k.a. ROY) holds the current record for the largest number of fully characterized organic crystal polymorphs. Four of these polymorphs were discovered or characterized since 2019,...

The low-resolution 3D-structure of porin, a channel-forming protein in E. coliouter membranes

1983 ◽  
Vol 41 ◽  
pp. 440-441
Author(s):  
A. Engel ◽  
D.L. Dorset ◽  
A. Massalski ◽  
J.P. Rosenbusch
Keyword(s):  
Crystal Packing ◽  
3D Structure ◽  
Gram Negative Bacteria ◽  
Protein Ratio ◽  
Crystal Forms ◽  
Large Molecules ◽  
Functional Studies ◽  
Voltage Dependent ◽  
Planar Membranes ◽  
Hexagonal Arrays

Porins represent a group of channel forming proteins that facilitate diffusion of small solutes across the outer membrane of Gram-negative bacteria, while excluding large molecules (>650 Da). Planar membranes reconstituted from purified matrix porin (OmpF protein) trimers and phospholipids have allowed quantitative functional studies of the voltage-dependent channels and revealed concerted activation of triplets. Under the same reconstitution conditions but using high protein concentrations porin aggregated to 2D lattices suitable for electron microscopy and image processing. Depending on the lipid-to- protein ratio three different crystal packing arrangements were observed: a large (a = 93 Å) and a small (a = 79 Å) hexagonal and a rectangular (a = 79 Å b = 139 Å) form with p3 symmetry for the hexagonal arrays. In all crystal forms distinct stain filled triplet indentations could be seen and were found to be morphologically identical within a resolution of (22 Å). It is tempting to correlate stain triplets with triple channels, but the proof of this hypothesis requires an analysis of the structure in 3 dimensions.

Progress in Organic Crystal Transistors for High-Performance Organic Electronics

2008 ◽  
Author(s):  
Jun Takeya ◽  
Takafumi Uemura ◽  
M. Uno ◽  
Masakazu Yamagishi ◽  
Yukihiro Tominari
Keyword(s):  
Organic Electronics ◽  
High Performance ◽  
Organic Crystal

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

scholarly journals Monitoring protein precipitates by in-house X-ray powder diffraction

2013 ◽  
Vol 28 (S2) ◽  
pp. S458-S469 ◽  
Author(s):  
Kenny Ståhl ◽  
Christian G. Frankær ◽  
Jakob Petersen ◽  
Pernille Harris
Keyword(s):  
Powder Diffraction ◽  
Protein Crystal ◽  
Data Sets ◽  
Crystal Forms ◽  
X Ray ◽  
Cell Parameters ◽  
X Ray Scattering ◽  
Source Organism ◽  
Peak Asymmetry ◽  
Overlapping Peaks

Powder diffraction from protein powders using in-house diffractometers is an effective tool for identification and monitoring of protein crystal forms and artifacts. As an alternative to conventional powder diffractometers a single crystal diffractometer equipped with an X-ray micro-source can be used to collect powder patterns from 1 µl samples. Using a small-angle X-ray scattering (SAXS) camera it is possible to collect data within minutes. A streamlined program has been developed for the calculation of powder patterns from pdb-coordinates, and includes correction for bulk-solvent. A number of such calculated powder patterns from insulin and lysozyme have been included in the powder diffraction database and successfully used for search-match identification. However, the fit could be much improved if peak asymmetry and multiple bulk-solvent corrections were included. When including a large number of protein data sets in the database some problems can be foreseen due to the large number of overlapping peaks in the low-angle region, and small differences in unit cell parameters between pdb-data and powder data. It is suggested that protein entries are supplied with more searchable keywords as protein name, protein type, molecular weight, source organism etc. in order to limit possible hits.

A Multidirectional Superelastic Organic Crystal by Versatile Ferroelastical Manipulation

2020 ◽  
Vol 59 (11) ◽  
pp. 4340-4343 ◽  
Author(s):  
Toshiyuki Sasaki ◽  
Shunichi Sakamoto ◽  
Yuichi Takasaki ◽  
Satoshi Takamizawa
Keyword(s):  
Organic Crystal

A plastically bendable and polar organic crystal

CrystEngComm ◽  
2021 ◽  
Author(s):  
Sotaro Kusumoto ◽  
Akira Sugimoto ◽  
Daisuke Kosumi ◽  
Yang Kim ◽  
Yoshihiro Sekine ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Polar Space ◽  
Organic Crystal ◽  
Space Group ◽  
High Dielectric

In this communication, an organic crystal of the polar space group Pc that is capable of plastically bending in response to external mechanical stress is reported, and its high dielectric...

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

Vibrational spectroscopic and Hirshfeld surface analysis of carvedilol crystal forms

2018 ◽  
Vol 553 (1-2) ◽  
pp. 261-271 ◽  
Author(s):  
Livia D. Prado ◽  
Alexandre B.X. Santos ◽  
Helvécio V.A. Rocha ◽  
Glaucio B. Ferreira ◽  
Jackson A.L.C. Resende
Keyword(s):  
Surface Analysis ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Crystal Forms
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