It’s not just the type of molecules a material is made of, the way in which they are arranged in space is important too. For many organic molecules, multiple crystal structures are known, and their physical properties can differ significantly. For example, a drug can be effective in one crystalline form but much less effective in another because it doesn’t dissolve fast enough.
Unfortunately, it has not been possible until recently to reliably predict crystal structures by using computer simulations. Frank Leusen and his co-workers at the University of Bradford (UK) are making significant progress on this front. As the scientists report in the journal Angewandte Chemie, they successfully used a quantum mechanical approach to predict the three known crystal structures of a sulfonamide.
Small differences in the production conditions, such as variations in pressure or temperature, can be enough to cause fine chemicals, such as pharmaceuticals, pigments, explosives, or agrochemicals, to crystallize in a different form. This can lead to problems with the production process or to undesirable product properties. It is correspondingly important to know which crystal structures are possible.
Scientists use computational chemistry methods to obtain information about molecular structures and crystallization processes. However, taking all of the parameters into account would exceed current computational capacities. “Precise, reliable predictions of the crystal structures of organic molecules have remained somewhat of a Holy Grail for crystallography,” says Leusen.
An international project regularly organizes blind studies in which research groups are asked to predict crystal structures. In 2007, Leusen and two co-workers were able to successfully predict the crystal structures of all four test compounds by using a quantum mechanical approach. A team led by Leusen then took on another test compound, a sulfonamide, which was the subject of a blind study in 2001; none of the participating teams was able to predict the crystal structure at the time. Interestingly, two additional, previously unknown crystal structures of this sulfonamide were discovered after the study. “By using the computational process developed by Marcus Neumann at Avant-garde Materials Simulation in Freiburg, Germany, we were able to correctly predict all three crystal structures,” says Leusen.
“Even though it is currently not possible to predict the outcome of a specific crystallization experiment under specific boundary conditions,” explains Leusen, “our results demonstrate that precise calculations of the lattice energy are sufficient to model crystallization thermodynamics and thus predict the different crystal structures of small organic molecules.”
Author: Frank J. J. Leusen, University of Bradford (UK), http://www.ipi.ac.uk/staff/individual/32
Title: Molecule VI, a Benchmark Crystal-Structure-Prediction Sulfonimide: Are Its Polymorphs Predictable?
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201007488
First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung
Staying in Shape
16.08.2018 | Max-Planck-Institut für molekulare Zellbiologie und Genetik
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
17.08.2018 | Materials Sciences
17.08.2018 | Information Technology
17.08.2018 | Physics and Astronomy