scholarly journals Crystal structure of posnjakite formed in the first crystal water-cooling line of the ANSTO Melbourne Australian Synchrotron MX1 Double Crystal Monochromator

2020 ◽  
Vol 76 (7) ◽  
pp. 1136-1138
Author(s):  
Stuart Mills ◽  
Jun Aishima ◽  
David Aragao ◽  
Tom Tudor Caradoc-Davies ◽  
Nathan Cowieson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Synchrotron Radiation ◽  
Hydrogen Bonds ◽  
Water Cooling ◽  
Double Crystal ◽  
Crystal Water ◽  
Double Crystal Monochromator ◽  
Jahn Teller ◽  
Additional Hydrogen

Exceptionally large crystals of posnjakite, Cu4SO4(OH)6(H2O), formed during corrosion of a Swagelock(tm) Snubber copper gasket within the MX1 beamline at the ANSTO-Melbourne, Australian Synchrotron. The crystal structure was solved using synchrotron radiation to R 1 = 0.029 and revealed a structure based upon [Cu4(OH)6(H2O)O] sheets, which contain Jahn–Teller-distorted Cu octahedra. The sulfate tetrahedra are bonded to one side of the sheet via corner sharing and linked to successive sheets via extensive hydrogen bonds. The sulfate tetrahedra are split and rotated, which enables additional hydrogen bonds.

scholarly journals Crystal water as the molecular glue for obtaining different co-crystal ratios: the case of gallic acid tris-caffeine hexahydrate

2018 ◽  
Vol 74 (4) ◽  
pp. 559-562
Author(s):  
L. Vella-Zarb ◽  
U. Baisch
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Gallic Acid ◽  
Carbonyl Oxygen ◽  
Crystalline Solid ◽  
Water Molecules ◽  
Crystal Water ◽  
Classical Hydrogen Bond ◽  
Additional Hydrogen

The crystal structure of the hexahydrate co-crystal of gallic acid and caffeine, C7H6O5·3C8H10N4O2·6H2O or GAL3CAF·6H2O, is a remarkable example of the importance of hydrate water acting as structural glue to facilitate the crystallization of two components of different stoichiometries and thus to compensate an imbalance of hydrogen-bond donors and acceptors. The water molecules provide the additional hydrogen bonds required to form a crystalline solid. Whereas the majority of hydrogen bonds forming the intermolecular network between gallic acid and caffeine are formed by crystal water, only one direct classical hydrogen bond between two molecules is formed between the carboxylic oxygen of gallic acid and the carbonyl oxygen of caffeine with d(D...A) = 2.672 (2) Å. All other hydrogen bonds either involve crystal water or utilize protonated carbon atoms as donors.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Amino Group ◽  
Asymmetric Unit ◽  
Partial Methylation ◽  
Space Groups ◽  
Carboxylate Groups ◽  
Anhydrous Compound ◽  
Additional Hydrogen

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

Double-crystal diffraction imaging with a small effective divergence source: application to the magneto-acoustic vibrations in FeBO3

2000 ◽  
Vol 33 (4) ◽  
pp. 1051-1058
Author(s):  
Ioanna Matsouli ◽  
Vladimir V. Kvardakov ◽  
José Baruchel
Keyword(s):  
Synchrotron Radiation ◽  
Spatial Dispersion ◽  
Angular Size ◽  
Standing Waves ◽  
Bragg Diffraction ◽  
Elastic Coupling ◽  
Acoustic Vibrations ◽  
Double Crystal ◽  
Double Crystal Monochromator ◽  
Diffraction Imaging

Ultrasonic standing waves, excited in FeBO3(111) crystal plates through magneto-elastic coupling, were visualized using monochromatic Bragg diffraction imaging (topography) with synchrotron radiation. The images depend strongly on whether diffraction by the sample occurs in the same plane as in the double-crystal monochromator, or in the perpendicular plane. The observations are explained by taking into account (a) the strong spatial dispersion which prevails because of the small effective divergence (angular size of the source as seen from a point in the specimen), which is less than one microradian in this experiment, and (b) the sample vibration and curvature.

An accurate theory of X-ray coplanar multiple SRMS diffractometry

2018 ◽  
Vol 74 (6) ◽  
pp. 673-680 ◽  
Author(s):  
V. G. Kohn
Keyword(s):  
Synchrotron Radiation ◽  
Plane Wave ◽  
Experimental Setup ◽  
Incident Plane Wave ◽  
Instrumental Function ◽  
Multiple Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Double Crystal Monochromator ◽  
Incident Plane

The article reports an accurate theory of X-ray coplanar multiple diffraction for an experimental setup that consists of a generic synchrotron radiation (SR) source, double-crystal monochromator (M) and slit (S). It is called for brevity the theory of X-ray coplanar multiple SRMS diffractometry. The theory takes into account the properties of synchrotron radiation as well as the features of diffraction of radiation in the monochromator crystals and the slit. It is shown that the angular and energy dependence (AED) of the sample reflectivity registered by a detector has the form of a convolution of the AED in the case of the monochromatic plane wave with the instrumental function which describes the angular and energy spectrum of radiation incident on the sample crystal. It is shown that such a scheme allows one to measure the rocking curves close to the case of the monochromatic incident plane wave, but only using the high-order reflections by monochromator crystals. The case of four-beam (220)(331)({\overline {11}}1) diffraction in Si is considered in detail.

scholarly journals A substrate selected by phage display exhibits enhanced side-chain hydrogen bonding to HIV-1 protease

2018 ◽  
Vol 74 (7) ◽  
pp. 690-694 ◽  
Author(s):  
Ian W. Windsor ◽  
Ronald T. Raines
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Molecular Recognition ◽  
Hydrogen Bonds ◽  
Phage Display ◽  
Directed Evolution ◽  
Side Chain ◽  
Endogenous Substrates ◽  
Hiv 1 ◽  
Additional Hydrogen

Crystal structures of inactive variants of HIV-1 protease bound to peptides have revealed how the enzyme recognizes its endogenous substrates. The best of the known substrates is, however, a nonnatural substrate that was identified by directed evolution. The crystal structure of the complex between this substrate and the D25N variant of the protease is reported at a resolution of 1.1 Å. The structure has several unprecedented features, especially the formation of additional hydrogen bonds between the enzyme and the substrate. This work expands the understanding of molecular recognition by HIV-1 protease and informs the design of new substrates and inhibitors.

scholarly journals Crystal structure of pentakis(ethylenediamine-κ2N,N′)lanthanum(III) trichloride–ethylenediamine–dichloromethane (1/1/1)

2014 ◽  
Vol 70 (11) ◽  
pp. 424-426 ◽  
Author(s):  
Hope T. Sartain ◽  
Richard J. Staples ◽  
Shannon M. Biros
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Bypass Procedure ◽  
Hydrogen Bonding Network ◽  
Additional Hydrogen

We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethylenediamine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethylenediamine molecule and three Cl−anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl−anions and the NH groups on the metal-bound ethylenediamine ligands. The free ethylenediamine molecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered molecule of dichloromethane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990).Acta Cryst.A46, 194–201].

A method to stabilize the incident X-ray energy for anomalous diffraction measurements

2017 ◽  
Vol 24 (4) ◽  
pp. 781-786
Author(s):  
Wenjia Wang ◽  
Xiaoyun Yang ◽  
Guangcai Chang ◽  
Pengfei An ◽  
Kewen Cha ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Data Collection ◽  
Absorption Edge ◽  
Feedback Loop ◽  
Inflection Point ◽  
Single Crystal Diffraction ◽  
Double Crystal ◽  
Anomalous Diffraction ◽  
X Ray ◽  
Double Crystal Monochromator

A method to calibrate and stabilize the incident X-ray energy for anomalous diffraction data collection is provided and has been successfully used at the single-crystal diffraction beamline 1W2B at the Beijing Synchrotron Radiation Facilities. Employing a feedback loop to control the movement of the double-crystal monochromator, this new method enables the incident X-ray energy to be kept within a 0.2 eV range at the inflection point of the absorption edge.

Formation and Structure of Cinchona Alkaloid (Bis-2,3-naphthalenediyl)orthoborate Salts

2000 ◽  
Vol 55 (11) ◽  
pp. 1083-1088 ◽  
Author(s):  
Maciej Kubicki ◽  
Teresa Borowiak ◽  
Krystyna Gawrońska ◽  
Jacek Gawroński
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Cinchona Alkaloids ◽  
Cinchona Alkaloid ◽  
Cd Spectra ◽  
Polar Solvents ◽  
X Ray ◽  
Solvent Molecules ◽  
Additional Hydrogen

A series of (bis-2,3-naphthalenediyl)orthoborate salts of Cinchona alkaloids has been synthesized and characterized. The interactions between ions in the salts have been studied by means of circular dichroism spectroscopy and X-ray crystal structure determination. The CD spectra of the dihydroquinidine salt show that in non-polar solvents it exists as a tightly held ion pair. The crystal structure of the cinchonidine salt proves the existence of ions in the solid state. The protonation takes place at the quinuclidine nitrogen atom. The hydrogen bonds connect cation and anion into one recognizable unit. Additional hydrogen bonds (with hydroxy group as a hydrogen donor and quinoline nitrogen atom as an acceptor) form infinite chains of cations along the [001] direction. There are cavities in the crystal structure that are partially filled by solvent molecules (acetone).

(5,16-Dimethyl-2,6,13,17-tetraazatricyclo[14.4.01,18.07,12]docosane-κ4 N)bis(perchlorato-κO)copper(II)

2007 ◽  
Vol 63 (11) ◽  
pp. m2674-m2675 ◽  
Author(s):  
Jong-Ha Choi ◽  
Keon Sang Ryoo ◽  
Ki-Min Park
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Macrocyclic Ligand ◽  
Distorted Octahedral Environment ◽  
Octahedral Environment ◽  
Distorted Octahedral ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Intramolecular Hydrogen

In the title compound, [Cu(ClO4)2(C20H40N4)], the CuII ion has a tetragonally distorted octahedral environment, with the four N atoms of the macrocyclic ligand in equatorial positions and the O atoms of two perchlorate groups in axial positions. The CuII ion is situated on an inversion centre. The macrocyclic ligand adopts its most stable trans-III conformation. The long axial Cu—O bond is the result of the Jahn–Teller effect. The crystal structure is stabilized by intramolecular hydrogen bonds between secondary N—H and the O atoms of the perchlorate groups.

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