Crystallography

Single and Mixed Phase TiO2 Powders by Excess Hydrolysis of Titanium Alkoxide

by Material Science

To investigate excess-hydrolysis of titanium alkoxides, TiO2 powders were fabricated from titanium-tetra-isopropoxide... more To investigate excess-hydrolysis of titanium alkoxides, TiO2 powders were fabricated from titanium-tetra-isopropoxide using 6:1 and 100:1 H2O:Ti (r) ratios. Powders were dried and fired at a range of temperatures (≤800ºC). Hydroxylation and organic content in powders were characterised using ATR-FTIR, laser Raman microspectroscopy, and elemental microanalysis; surface area and pore size distribution were evaluated using N2 gas adsorption; phase composition was analysed using XRD and laser Raman microspectroscopy; and crystallite size was evaluated by XRD, TEM and SEM. Results showed near-complete hydrolysis in a predominantly aqueous medium (r = 100), resulting in precipitated crystalline powders exhibiting brookite and anatase, which begin to transform to rutile below 500°C. Powders precipitated in a predominantly organic medium (r = 6) underwent partial hydrolysis, were highly porous and exhibited an amorphous structure, with crystallisation of anatase occurring at ~300°C and transformation to rutile beginning at 500°-600°C.

Crystal Structure of ChrR - A Quinone Reductase with the Capacity to Reduce Chromate

by Sebastien Poulain

PLoS ONE, 2012
Eswaramoorthy S and Poulain S (equal contributors), Hienerwadel R, Brémond N, Sylvester MD, Zhang Y-B, Berthomieu C, Van Der Lelie D, Matin A.

The Escherichia coli ChrR enzyme is an obligatory two-electron quinone reductase that has many applications, such as... more The Escherichia coli ChrR enzyme is an obligatory two-electron quinone reductase that has many applications, such as in chromate bioremediation. Its crystal structure, solved at 2.2 Å resolution, shows that it belongs to the flavodoxin superfamily in which flavin mononucleotide (FMN) is firmly anchored to the protein. ChrR crystallized as a tetramer, and size exclusion chromatography showed that this is the oligomeric form that catalyzes chromate reduction. Within the tetramer, the dimers interact by a pair of two hydrogen bond networks, each involving Tyr128 and Glu146 of one dimer and Arg125 and Tyr85 of the other; the latter extends to one of the redox FMN cofactors. Changes in each of these amino acids enhanced chromate reductase activity of the enzyme, showing that this network is centrally involved in chromate reduction.

Angels around the Crystal: the Prayer Book of King Wladislas and the Treasure Hunts of Henry the Bohemian, Aries: Journal for the Study of Western Esotericism 5 (2005): 1-32.

by Benedek Lang

Pre-print. Please refer to the published version.

Spectroscopic, Structural, and Theoretical Studies of Halide Complexes with a Urea-Based Tripodal Receptor

by Bryan Wong

Inorganic Chemistry, 51, 4274 (2012)

A Quinoline Based bis-Urea Receptor for Anions: A Selective Receptor for Hydrogen Sulfate

by Bryan Wong

Natural Product Communications, 7, 301 (2012)

A hitherto unrecognised band in the Raman spectra of silica rocks: influence of hydroxylated Si–O bonds (silanole) on the Raman moganite band in chalcedony and flint (SiO2)

by Patrick Schmidt

Patrick Schmidt, Ludovic Bellot-Gurlet, Aneta Slodczyk and François Fröhlich, 2012, Physics and Chemistry of Minerals, 39(6), 455-464.

Charge-Assisted Encapsulation of Two Chlorides by a Hexaprotonated Azamacrocycle

by Bryan Wong

Crystal Growth & Design, 10, 1478 (2010)

Formation of an Amine-Water Cyclic Pentamer: A New Type of Water Cluster in a Polyazacryptand

by Bryan Wong

Crystal Growth & Design, 10, 1486 (2010)

A C3 Symmetric Nitrate Complex with a Tripodal Receptor

by Bryan Wong

Crystal Growth & Design, 11, 959 (2011)

(E)-4-[(4-Nitrophenyl)diazenyl]phenyl anthracene-9-carboxylate

by Bryan Wong

Acta Crystallographica Section E, E64, o2258 (2008)

(E)-2-{Ethyl[4-(4-nitrophenyldiazenyl)-phenyl]amino}ethyl anthracene-9-carboxylate

by Bryan Wong

Acta Crystallographica Section E, E64, o595 (2008)

Structures of Human Deoxycytidine Kinase Product Complexes

by Valerie Clark

Symmetry Breaking and Order in the Age of Quasicrystals

by Ron Lifshitz

Ron Lifshitz.  Isr. J. Chem. 51 (2011) 1156-1167.

The discovery of quasicrystals has changed our view of some of the most basic notions related to the condensed state... more The discovery of quasicrystals has changed our view of some of the most basic notions related to the condensed state of matter. Before the age of quasicrystals, it was believed that crystals break the continuous translation and rotation symmetries of the liquid-phase into a discrete lattice of translations, and a finite group of rotations. Quasicrystals, on the other hand, possess no such symmetrie—there are no translations, nor, in general, are there any rotations, leaving them invariant. Does this imply that no symmetry is left, or that the meaning of symmetry should be revised? We review this and other questions related to the liquid-to-crystal symmetry-breaking transition using the notion of indistinguishability. We characterize the order-parameter space, describe the different elementary excitations, phonons and phasons, and discuss the nature of dislocations—keeping in mind that we are now living in the age of quasicrystals.

Cloning, expression, purification, crystallization and preliminary X-ray analysis of NodS N-methyltransferase from Bradyrhizobium japonicum WM9

by Ozgur Cakici

Functional role of the conserved active site proline of triosephosphate isomerase

by Marco G. Casteleijn

Structural studies show that the A178L mutation in the C-terminal hinge of the catalytic loop-6 of triosephosphate isomerase (TIM) induces a closed-like conformation …

by Marco G. Casteleijn

Crystallographic binding studies with an engineered monomeric variant of triosephosphate isomerase

by Marco G. Casteleijn

Protein engineering of non-natural enzymes

by Marco G. Casteleijn

65) Acridine 0.75-hydrate

by Dr Andreas Lemmerer aka Crystal Magician

Einat Schur,* Joel Bernstein, Andreas Lemmerer and Radion Vainer, Acta Crystallographica (2011), E67, o2761.

The title compound, C13H9N0.75H2O was obtained during a study of the polymorphic system of acridine, by slow... more The title compound, C13H9N0.75H2O was obtained during a study of the polymorphic system of acridine, by slow evaporation from an ethanol–water solution. There are two acridine molecules (indicated by I and II, respectively) and one and a half water molecules in the asymmetric unit. The half-molecule of water is located on a crystallographic twofold axis. The crystal structure is built up from two threads of molecule II sewn together with water molecules through O-H...O and O—H...N hydrogen bonds from one side and with pi–pi interactions [centroid–centroid distance = 3.640 (3) and 3.7431 (3) A ˚ ] between overlapping molecules II on the other side. Molecule I is attached to this thread from both sides by C—H...O hydrogen bonds. The threads are connected to each other by pi–pi interactions [centroid–centroid distances = 3.582 (3) and 3.582 (3) A ˚ ] between the inner side of molecule I and stabilized by a C—H...pi interaction on the other side of molecule I. This thread with rows of molecule I hanging on its sides is generated by translation perpendicular to the a axis.

67) Isonicotinamide—2-naphthoic acid (1/1)

by Dr Andreas Lemmerer aka Crystal Magician

Lee G. Madeley, Demetrius C. Levendis and Andreas Lemmerer,* Acta Crystallographica (2011), E67, o3440.

In the title 1:1 adduct, C6H6N2O.C11H8O2, the amide group is slightly twisted out of the plane of the aromatic ring,... more In the title 1:1 adduct, C6H6N2O.C11H8O2, the amide group is slightly twisted out of the plane of the aromatic ring, with a C—C—C—N torsion angle of 25.11 (19), whereas the carboxylic acid group is approximately coplanar with the bicylic ring system, with a C—C—C—O torsion angle of 10.9 (2). The amide groups from two isonicotinamide molecules form a dimer via N—H...O hydrogen bonds. In addition, the 2-naphthanoic acid molecule is hydrogen bonded to the pyridine unit of an isonicotinamide molecule via an O—H...N hydrogen bond. This gives rise to a centrosymmetric four molecule chain, which is cross-linked by further N—H...O hydrogen bonds from the amide group.