A5008857429- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Crystallography and molecular interactions
- Chemical Thermodynamics and Molecular Structure
- Pigment Synthesis and Properties
- Cultural Heritage Materials Analysis
- Enzyme Structure and Function
- Metal-Organic Frameworks: Synthesis and Applications
- Advanced NMR Techniques and Applications
- Polymer Synthesis and Characterization
- Crystal structures of chemical compounds
- Food Chemistry and Fat Analysis
- Computational Drug Discovery Methods
- Crystal Structures and Properties
- Taxation and Legal Issues
- Machine Learning in Materials Science
- Corporate Taxation and Avoidance
- Solid-state spectroscopy and crystallography
- Chemical Synthesis and Characterization
- Molecular spectroscopy and chirality
- Covalent Organic Framework Applications
- Economic and Fiscal Studies
- Thermal and Kinetic Analysis
- Inorganic Fluorides and Related Compounds
- Phase Equilibria and Thermodynamics
Goethe University Frankfurt
2007-2023
University of Copenhagen
2012-2021
University of Cambridge
2004-2012
Radboud University Nijmegen
1999-2011
University of Freiburg
2008-2011
University College London
2011
Philipps University of Marburg
2010
Nikolaev Institute of Inorganic Chemistry
2010
Cambridge Crystallographic Data Centre
2002-2009
University of Manchester
2008
The program Mercury , developed by the Cambridge Crystallographic Data Centre, is designed primarily as a crystal structure visualization tool. A new module of functionality has been produced, called Materials Module which allows highly customizable searching structural databases for intermolecular interaction motifs and packing patterns. This also includes ability to perform similarity calculations between structures containing same compound. In addition range further enhancements added in...
Since its original release, the popular crystal structure visualization program Mercury has undergone continuous further development. Comparisons between structures are facilitated by ability to display multiple simultaneously and overlay them. Improvements have been made many aspects of visual display, including addition depth cueing, highly customizable lighting background effects. Textual numeric data associated with can be shown in tables or spreadsheets, latter opening up new ways...
DASH is a user-friendly graphical-user-interface-driven computer program for solving crystal structures from X-ray powder diffraction data, optimized molecular structures. Algorithms multiple peak fitting, unit-cell indexing and space-group determination are included as part of the program. Molecular models can be read in number formats automatically converted to Z-matrices which flexible torsion angles identified. Simulated annealing used search global minimum space that describes agreement...
We report on the organization and outcome of fourth blind test crystal structure prediction, an international collaborative project organized to evaluate present state in computational methods predicting structures small organic molecules. There were 14 research groups which took part, using a variety generate rank most likely for four target systems: three single-component 1:1 cocrystal. Participants challenged predict systems, given only their molecular diagrams, while recently determined...
Following on from the success of previous crystal structure prediction blind tests (CSP1999, CSP2001, CSP2004 and CSP2007), a fifth such collaborative project (CSP2010) was organized at Cambridge Crystallographic Data Centre. A range methodologies used by participating groups in order to evaluate ability current computational methods predict structures six organic molecules chosen as targets for this test. The first four targets, two rigid molecules, one semi-flexible molecule 1:1 salt,...
In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal determined from X-ray powder diffraction (XRPD) data and published in an IUCr journal were DFT-D compared SX The on average slightly less accurate atomic coordinates of XRPD do lead systematically higher root mean square Cartesian displacement (RMSCD) values upon energy...
Abstract Organic molecules, such as pharmaceuticals, agro-chemicals and pigments, frequently form several crystal polymorphs with different physicochemical properties. Finding has long been a purely experimental game of trial-and-error. Here we utilize in silico polymorph screening combination rationally planned crystallization experiments to study the polymorphism pharmaceutical compound Dalcetrapib, 10 torsional degrees freedom one most flexible molecules ever studied computationally. The...
The physicochemical properties of molecular crystals, such as solubility, stability, compactability, melting behaviour and bioavailability, depend on their crystal form1. In silico form selection has recently come much closer to realization because the development accurate affordable free-energy calculations2-4. Here we redefine state art, primarily by improving accuracy calculations, constructing a reliable experimental benchmark for solid-solid differences, quantifying statistical errors...
Solid-state grinding is explored as a means of selectively preparing specific stoichiometric or polymorphic modifications crystalline supramolecular complexes, cocrystals. In research involving cocrystals the model pharmaceutical compound caffeine prepared via solid-state and solution crystallization, it has been demonstrated that these two methods preparation are not always coterminous with respect to cocrystal product obtained. Examined herein structures five previously unreported...
Abstract A family of 16 isomolecular salts (3‐XpyH) 2 [MX′ 4 ] (3‐XpyH=3‐halopyridinium; M=Co, Zn; X=(F), Cl, Br, (I); X′=Cl, I) each containing rigid organic cations and tetrahedral halometallate anions has been prepared characterized by X‐ray single crystal and/or powder diffraction. Their structures reflect the competition cooperation between non‐covalent interactions: NH⋅⋅⋅X′M hydrogen bonds, CX⋅⋅⋅X′M halogen bonds π–π stacking. The latter are essentially unchanged in strength across...
This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for purpose assessing correctness experimental organic crystal structures and enhancing information content purely data. 241 from August 2008 issue Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between minimized subjected to statistical analysis. r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible...
Yellow crystalline salts (3-XpyH)2[CuCl4] (3-XpyH = 3-halopyridinium, X Cl, Br) lose HCl upon exposure to air in an open vessel, yielding quantitatively blue coordination compounds [CuCl2(3-Xpy)2]. The reaction is prevented if the vessel sealed, but can be driven forward under such conditions by providing a trapping agent for HCl, as aqueous solution of AgNO3. requires cleavage Cu-Cl and N-H bonds formation Cu-N bonds. metal geometry also changes from distorted tetrahedral square planar....
Abstract The results of the application a density functional theory method incorporating dispersive corrections in 2010 crystal structure prediction blind test are reported. correctly predicted four out six experimental structures. Three correct predictions were found to have lowest lattice energy any for that molecule. structures all compounds during generation phase simulations, indicating tailor‐made force fields used screening valid and engine, which combines Monte Carlo parallel...
Stabilizing the unstable: In textbooks barbituric acid is always drawn in its keto tautomeric form, which indeed preferred solution and most polymorphic phases. However, phase IV, obtained by grinding, consists of molecules enol as shown neutron powder diffraction. This found to be stable one at room temperature; "unstable" tautomer stabilized a higher number hydrogen bonds.
Abstract The active pharmaceutical ingredient rotigotine—a dopamine agonist for the treatment of Parkinson’s and restless leg diseases—was known to exist in only one polymorphic form since 1985. In 2008, appearance a thermodynamically more stable significantly less soluble polymorph led massive batch recall followed by economic public health implications. Here, we carry out state-of-the-art computational crystal structure prediction, revealing late-appearing without using any prior...
A computer program has been written that removes suspicious crystal structures from the Cambridge Structural Database and clusters remaining as polymorphs or redeterminations. For every set of redeterminations, one structure is selected to be best representative polymorph. The results, 243,355 well determined grouped by unique polymorph, are presented analysed.
Hydrogen chloride gas (HCl) is absorbed (and reversibly released) by a nonporous crystalline solid, [CuCl2(3-Clpy)2] (3-Clpy = 3-chloropyridine), under ambient conditions leading to conversion from the blue coordination compound yellow salt (3-ClpyH)2[CuCl4]. These reactions require substantial motions within solid including change in copper environment square planar tetrahedral. This process also involves cleavage of covalent bond gaseous molecules (H−Cl) and bonds molecular (Cu−N)...
Based on a thorough and critical analysis of the commercial crystal structure prediction studies 41 pharmaceutical compounds, we conclude that for between 15 45% all small-molecule drugs currently market most stable experimentally observed polymorph is not thermodynamically appearance latter kinetically hindered.
A versatile crystal-growth simulation program, based on the Monte Carlo algorithm, is introduced. It enables handling of any crystallographic orientation. The crystal modeled by a set molecular interactions, which are obtained from mechanics calculations. motherphase parametrized its bulk thermodynamic properties. As an example, program was used to simulate growth various fat crystals. results show importance details structure, energetics, and actual conditions upon morphology. model intends...
Ligand flexibility permits framework rearrangement upon evacuation and gas uptake in a new family of porous MOFs.
Hydrogen bonding leads the way: Reaction of nonporous crystalline coordination compound 1 with HCl gas results in conversion into salt 2 (see picture) following chemisorption and insertion CuN bonds. Powder diffraction studies show that [CuBr2Cl2]2− ions formed are reoriented to maximize strength hydrogen bonds halogen by preferentially involving Cl rather than Br ligands as acceptor sites.
Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The were collected using the automated tomography (ADT) technique. solution and refinement route first validated on basis known tri-p-benzamide. same procedure then applied to solve previously unknown tetra-p-benzamide. In tetra-p-benzamide, an unusual hydrogen-bonding scheme realised; is, however, in perfect agreement with solid-state NMR data.
The conversion of aqueous dispersion nanostructured lipid carriers (NLCs) into dry powder by spray drying could be a useful approach to render NLCs with better physical chemical stability than the dispersion. In this study, NLC containing fenofibrate was converted dry, easily reconstitutable using drying. A central composite face centered design (CCFD) used investigate influence ratio protectant (mannitol and trehalose) crystallinity spray-dried on particle size, yield residual moisture...
Elucidating the structure relationships and transformation pathways of solid forms gandotinib was an enormous challenge. Only seven eleven experimentally observed crystallized directly from solution: a neat form (I), tetrahydrate (Hy4), 3.0–3.7-hydrate (HyY), four solvates (methanol, n-propanol, n-butanol, N-methyl-2-pyrrolidone). The remaining (II, Hy2.2, Hy1.3, HyX) were produced by dehydration and/or rehydration processes. Interconversion anhydrates hydrates with small changes in relative...
In this paper we describe several new pieces of software that allow the Cambridge Structural Database (CSD) to be searched for solvated and unsolvated crystal structures. One program finds all pairs structures same chemical compound a given solvent; another were grown from particular solvent. addition, an algorithm was implemented determine stereochemistry structure its 3-D atomic coordinates. Results water as solvent molecule are presented. It is found about 25% form hydrates. If soluble in...