scholarly journals anti-1-(Benzylamino)glyoxime. Corrigendum

2022 ◽  
Vol 78 (1) ◽  
pp. 97-97
Author(s):  
Yavuz Köysal ◽  
Şamil Işık ◽  
Nursabah Sarıkavaklı ◽  
Fatih Eyduran
Keyword(s):  
Acta Cryst

In the paper by Köysal et al. [Acta Cryst. (2004), E60, o515–o516], there was an error in the name of the last author.

Crystal-growth kinetics of protein single crystals along capillary tubes in the gel-acupuncture technique

1999 ◽  
Vol 55 (2) ◽  
pp. 577-580 ◽  
Author(s):  
Abel Moreno ◽  
Manuel Soriano-García
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Capillary Tube ◽  
Crystal Growth Rate ◽  
Equilibrium Studies ◽  
Acta Cryst ◽  
Average Growth ◽  
X Ray Crystallography ◽  
Growing Cell ◽  
Kinetics Of

In attempts to obtain protein crystals of a sufficient size for structural studies, lack of knowledge of the physicochemical properties of protein solutions and of their crystal-growth behaviour lead to a bottleneck for drug design as well as for X-ray crystallography. Most formal investigations on crystal-growth phenomena have been focused on equilibrium studies, where the protein is soluble, and on the kinetics of crystal growth, which is related to both nucleation and crystal-growth phenomena. The aim of this work is to measure the crystal-growth rate along a capillary tube used as a growing cell. These experiments were carried out using the gel-acupuncture technique [García-Ruiz et al. (1993). Mater. Res. Bull. 28, 541–546; García-Ruiz & Moreno (1994). Acta Cryst. D50, 484–490; García-Ruiz & Moreno (1997). J. Cryst. Growth, 178, 393–401]. Crystal-growth investigations took place using lysozyme and thaumatin I as standard proteins. The maximum average growth rate obtained in the lower part of the capillary tube was about 35 Å s−1 and the minimum average growing rate in the upper part of the capillary tube was about 8 Å s−1. The crystal-growth rate as a function of the supersaturation was experimentally estimated at a constant height along the capillary tube.

Bis[4-amino-N-(pyrimidin-2-yl)benzenesulfonamido]diamminecopper(II): aqua or ammine ligands?

2013 ◽  
Vol 69 (11) ◽  
pp. 1221-1224 ◽  
Author(s):  
Fangfang Pan ◽  
Irmgard Kalf ◽  
Ulli Englert
Keyword(s):  
High Resolution ◽  
Equatorial Plane ◽  
Title Compound ◽  
Aqua Ligand ◽  
Acta Cryst ◽  
The Relationship

Diffraction results obtained at 100 and 291 K, the former at high resolution, are reported for the title compound, [Cu(C10H9N4O2S)2(NH3)2] or [Cu(sulfa)2(NH3)2] [Hsulfa is 4-amino-N-(pyrimidin-2-yl)benzenesulfonamide]. The CuIIcation is coordinated by two N-atom donors from a bidentate sulfa ligand, by two ammonia molecules in the equatorial plane and by a monohapto (η1) sulfadiazine at the apex of a distorted square pyramid. The present interpretation and two earlier reports [Brown, Cook & Sengier (1987).Acta Cryst.C43, 2332–2334; Tommasino, Renaud, Luneau & Pilet (2011).Polyhedron,30, 1663–1670] disagree about the nature and geometry of the ligands. The relationship between the present result and the former is discussed, and evidence is provided that the latter erroneously assigned an ammine as an aqua ligand.

scholarly journals Crystal structure of a new monoclinic polymorph ofN-(4-methylphenyl)-3-nitropyridin-2-amine

2014 ◽  
Vol 70 (8) ◽  
pp. 58-61
Author(s):  
Aina Mardia Akhmad Aznan ◽  
Zanariah Abdullah ◽  
Vannajan Sanghiran Lee ◽  
Edward R. T. Tiekink
Keyword(s):  
Three Dimensional ◽  
Basis Set ◽  
Dihedral Angles ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Common Features ◽  
Compound C ◽  
B3lyp Level ◽  
The Common ◽  
Independent Molecules

The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, withZ′ = 4) of the previously reported monoclinic (P21/c, withZ′ = 2) form [Akhmad Aznanet al.(2010).Acta Cryst.E66, o2400]. Four independent molecules comprise the asymmetric unit, which have the common features of asyndisposition of the pyridine N atom and the toluene ring, and an intramolecular amine–nitro N—H...O hydrogen bond. The differences between molecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6–311 g+(d,p) basis set] has the same features except that the entire molecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C—H...O, C—H...π, nitro-N—O...π and π–π interactions [inter-centroid distances = 3.649 (2)–3.916 (2) Å].

scholarly journals Crystal structure of bis(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ2N2,N3]cobalt(II)

2015 ◽  
Vol 71 (5) ◽  
pp. 452-454 ◽  
Author(s):  
Abdelhakim Laachir ◽  
Fouad Bentiss ◽  
Salaheddine Guesmi ◽  
Mohamed Saadi ◽  
Lahcen El Ammari
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Title Complex ◽  
Octahedral Coordination ◽  
Maximum Deviation ◽  
Coordination Geometry ◽  
Acta Cryst ◽  
Π Interactions ◽  
The Mean

In the mononuclear title complex, [Co(N3)2(C12H8N4S)2], the cobalt(II) atom is located on an inversion centre and displays an axially weakly compressed octahedral coordination geometry. The equatorial positions are occupied by the N atoms of two 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole ligands, whereas the axial positions are occupied by N atoms of the azide anions. The thiadiazole and pyridine rings linked to the metal are almost coplanar, with a maximum deviation from the mean plane of 0.0273 (16) Å. The cohesion of the crystal is ensured by weak C—H...N hydrogen bonds and by π–π interactions between pyridine rings [intercentroid distance = 3.6356 (11) Å], forming a layered arrangement parallel to (001). The structure of the title compound is isotypic with that of the analogous nickel(II) complex [Laachiret al.(2013).Acta Cryst.E69, m351–m352].

Program construction for macromolecule atomic model refinement based on the fast Fourier transform and fast differentiation algorithms; erratum

1986 ◽  
Vol 42 (1) ◽  
pp. 57-57
Author(s):  
V. Yu. Lunin ◽  
A. G. Urzhumstev
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Atomic Model ◽  
Model Refinement ◽  
Acta Cryst ◽  
Program Construction

In Lunin & Urzhumtsev [Acta Cryst. (1985), A41, 327-333] references to Lifshitz (Agarwal, 1981) on pages 327 and 329 should be amended to Lifchitz (Agarwal, 1981).

New Measure of Distortion for Coordination Polyhedra

1998 ◽  
Vol 54 (6) ◽  
pp. 766-773 ◽  
Author(s):  
E. Makovicky ◽  
T. Balić-Žunić
Keyword(s):  
Phase Transformation ◽  
Coordination Sphere ◽  
Central Atom ◽  
Global Measure ◽  
Acta Cryst ◽  
Coordination Polyhedra ◽  
The Real

A new global measure of distortion for coordination polyhedra is proposed, based on a comparison of the ratios Vs (circumscribed sphere)/Vp (polyhedron) calculated, respectively, for the real and ideal polyhedra of the same number of coordinated atoms which have the same circumscribed sphere. This formula can be simplified to υ (%) = 100[Vi (ideal) − Vr (real)]/Vi , where Vi and Vr are the volumes of the above-defined polyhedra. The global distortion can be combined with other polyhedral characteristics, e.g. with the eccentricity of the central atom in the polyhedron or with the degree of sphericity of the coordination sphere [Balić Zõunić & Makovicky (1996). Acta Cryst. B52, 78–81].Vs /Vp ratios are given for a number of ideal polyhedra, including several types of trigonal coordination prisms, with the aim of facilitating the distortion calculations. The application examples included in the paper are: complex sulfides based on PbS and SnS archetypes, coordination polyhedra of large cations in feldspars, a phase transformation in a monoclinic amphibole and the subdivision of structures isopointal to ilmenite.

scholarly journals Lattice constants and thermal expansion of H2O and D2O Ice Ih between 10 and 265 K. Addendum

2012 ◽  
Vol 68 (1) ◽  
pp. 91-91 ◽  
Author(s):  
K. Röttger ◽  
A. Endriss ◽  
Jörg Ihringer ◽  
S. Doyle ◽  
W. F. Kuhs
Keyword(s):  
Thermal Expansion ◽  
Unit Cell ◽  
Acta Cryst ◽  
Lattice Constants ◽  
Temperature Range ◽  
Polynomial Fit ◽  
Polynomial Expression ◽  
Cell Data ◽  
Cell Volumes ◽  
Volume Cell

In a previous paper we reported the lattice constants and thermal expansion of normal and deuterated ice Ih [Röttger et al. (1994). Acta Cryst. B50, 644–648]. Synchrotron X-ray powder diffraction data were used to obtain the lattice constants and unit-cell volumes of H2O and D2O ice Ih in the temperature range 15–265 K. A polynomial expression was given for the unit-cell volumes. It turns out that the coefficients quoted have an insufficient number of digits to faithfully reproduce the volume cell data. Here we provide a table with more significant digits. Moreover, we also provide the coefficients of a polynomial fit to the previously published a and c lattice constants of normal and deuterated ice Ih for the same temperature range.

A Comparison of Two Algorithms for Electron-Density Map Improvement by Introduction of Atomicity: Skeletonization, and Map Sorting Followed by Refinement

1998 ◽  
Vol 54 (1) ◽  
pp. 81-85 ◽  
Author(s):  
F. M. D. Vellieux
Keyword(s):  
Electron Density ◽  
Initial Density ◽  
Acta Cryst ◽  
Density Maps ◽  
Resolution Electron ◽  
Crystallographic Symmetry ◽  
Density Map ◽  
Ornithine Transcarbamoylase ◽  
Electron Density Map ◽  
Pseudo Atom

A comparison has been made of two methods for electron-density map improvement by the introduction of atomicity, namely the iterative skeletonization procedure of the CCP4 program DM [Cowtan & Main (1993). Acta Cryst. D49, 148–157] and the pseudo-atom introduction followed by the refinement protocol in the program suite DEMON/ANGEL [Vellieux, Hunt, Roy & Read (1995). J. Appl. Cryst. 28, 347–351]. Tests carried out using the 3.0 Å resolution electron density resulting from iterative 12-fold non-crystallographic symmetry averaging and solvent flattening for the Pseudomonas aeruginosa ornithine transcarbamoylase [Villeret, Tricot, Stalon & Dideberg (1995). Proc. Natl Acad. Sci. USA, 92, 10762–10766] indicate that pseudo-atom introduction followed by refinement performs much better than iterative skeletonization: with the former method, a phase improvement of 15.3° is obtained with respect to the initial density modification phases. With iterative skeletonization a phase degradation of 0.4° is obtained. Consequently, the electron-density maps obtained using pseudo-atom phases or pseudo-atom phases combined with density-modification phases are much easier to interpret. These tests also show that for ornithine transcarbamoylase, where 12-fold non-crystallographic symmetry is present in the P1 crystals, G-function coupling leads to the simultaneous decrease of the conventional R factor and of the free R factor, a phenomenon which is not observed when non-crystallographic symmetry is absent from the crystal. The method is far less effective in such a case, and the results obtained suggest that the map sorting followed by refinement stage should be by-passed to obtain interpretable electron-density distributions.

scholarly journals Crystal structure of 2,4-dinitrophenyl 4-methylbenzenesulfonate: a new polymorph

2015 ◽  
Vol 71 (9) ◽  
pp. 1085-1088 ◽  
Author(s):  
Tyler A. Cooley ◽  
Sean Riley ◽  
Shannon M. Biros ◽  
Richard J. Staples ◽  
Felix N. Ngassa
Keyword(s):  
Crystal Structure ◽  
Nucleophilic Substitution ◽  
Torsion Angle ◽  
Title Compound ◽  
Substitution Reaction ◽  
Sulfonate Group ◽  
Acta Cryst ◽  
Crystal Stability ◽  
Compound C ◽  
Centroid Distance

The title compound, C13H10N2O7S, was synthesizedviaa nucleophilic substitution reaction between 2,4-dinitrophenol andp-toluenesulfonyl chloride. This crystal structure is a polymorph of CSD entry WUVYUH [Vembuet al.(2003).Acta Cryst, E59, o378–380]. The aromatic substituents on the sulfonate group are orientedgaucheto one another with a C—O—S—C torsion angle of −62.0 (3)°. The supramolecular features that contribute to the crystal stability are offset π–π [centroid–centroid distance = 3.729 (2) Å] and multiple C—H...O interactions.

scholarly journals About systematic errors in charge-density studies

2014 ◽  
Vol 70 (3) ◽  
pp. 248-256 ◽  
Author(s):  
Julian Henn ◽  
Kathrin Meindl
Keyword(s):  
Charge Density ◽  
Gaussian Distribution ◽  
Gaussian Model ◽  
Systematic Errors ◽  
Parameter Estimates ◽  
Published Data ◽  
Artificial Data ◽  
Acta Cryst ◽  
Zero Values ◽  
Data Yield

The formerly introduced theoreticalRvalues [Henn & Schönleber (2013).Acta Cryst.A69, 549–558] are used to develop a relative indicator of systematic errors in model refinements,Rmeta, and applied to published charge-density data. The counter ofRmetagives an absolute measure of systematic errors in percentage points. The residuals (Io−Ic)/σ(Io) of published data are examined. It is found that most published models correspond to residual distributions that are not consistent with the assumption of a Gaussian distribution. The consistency with a Gaussian distribution, however, is important, as the model parameter estimates and their standard uncertainties from a least-squares procedure are valid only under this assumption. The effect of correlations introduced by the structure model is briefly discussed with the help of artificial data and discarded as a source of serious correlations in the examined example. Intensity and significance cutoffs applied in the refinement procedure are found to be mechanisms preventing residual distributions from becoming Gaussian. Model refinements against artificial data yield zero or close-to-zero values forRmetawhen the data are not truncated and small negative values in the case of application of a moderate cutoffIo> 0. It is well known from the literature that the application of cutoff values leads to model bias [Hirshfeld & Rabinovich (1973).Acta Cryst.A29, 510–513].

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