A test of crystal structure prediction of small organic molecules

2000 ◽  
Vol 56 (4) ◽  
pp. 697-714 ◽  
Author(s):  
Jos P. M. Lommerse ◽  
W. D. Sam Motherwell ◽  
Herman L. Ammon ◽  
Jack D. Dunitz ◽  
Angelo Gavezzotti ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Lattice Energy ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Compound A ◽  
Small Organic Molecules ◽  
Wide Range ◽  
Field Methodology ◽  
Selection Of

A collaborative workshop was held in May 1999 at the Cambridge Crystallographic Data Centre to test how well currently available methods of crystal structure prediction perform when given only the atomic connectivity for an organic compound. A blind test was conducted on a selection of four compounds and a wide range of methodologies representing the principal computer programs currently available were used. There were 11 participants who were allowed to propose at most three structures for each compound. No program gave consistently reliable results. However, seven proposed structures were close to an experimental one and were classified as `correct'. One compound occurred in two polymorphs, but only one form was predicted correctly among the calculated structures. The basic problem with lattice energy based methods of crystal structure prediction is that many structures are found within a few kJ mol−1 of the global minimum. The fine detail of the force-field methodology and parametrization influences the energy ranking within each method. Nevertheless, present methods may be useful in providing a set of structures as possible polymorphs for a given molecular structure.

scholarly journals Blind crystal structure prediction of a novel second polymorph of 1-hydroxy-7-azabenzotriazole

2006 ◽  
Vol 62 (4) ◽  
pp. 642-650 ◽  
Author(s):  
Harriott Nowell ◽  
Christopher S. Frampton ◽  
Julie Waite ◽  
Sarah L. Price
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Structure Refinement ◽  
Lattice Energy ◽  
Polymorphic Form ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Coupling Reagent ◽  
Energy Penalty ◽  
Alcohol Solvents

The commercially available peptide coupling reagent 1-hydroxy-7-azabenzotriazole has been shown to crystallize in two polymorphic forms. The two polymorphs differ in their hydrogen-bonding motif, with form I having an R_2^2(10) dimer motif and form II having a C(5) chain motif. The previously unreported form II was used as an informal blind test of computational crystal structure prediction for flexible molecules. The crystal structure of form II has been successfully predicted blind from lattice-energy minimization calculations following a series of searches using a large number of rigid conformers. The structure for form II was the third lowest in energy with form I found as the global minimum, with the energy calculated as the sum of the ab initio intramolecular energy penalty for conformational distortion and the intermolecular lattice energy which is calculated from a distributed multipole representation of the charge density. The predicted structure was sufficiently close to the experimental structure that it could be used as a starting model for crystal structure refinement. A subsequent limited polymorph screen failed to yield a third polymorphic form, but demonstrated that alcohol solvents are implicated in the formation of the form I dimer structure.

Using crystal structure prediction to rationalize the hydration propensities of substituted adamantane hydrochloride salts

2016 ◽  
Vol 72 (4) ◽  
pp. 551-561 ◽  
Author(s):  
Sharmarke Mohamed ◽  
Durga Prasad Karothu ◽  
Panče Naumov
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Energy Landscape ◽  
Lattice Energy ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Hydrochloride Salt ◽  
Salt Structure ◽  
A Chain ◽  
Experimental Crystal

The crystal energy landscapes of the salts of two rigid pharmaceutically active molecules reveal that the experimental structure of amantadine hydrochloride is the most stable structure with the majority of low-energy structures adopting a chain hydrogen-bond motif and packings that do not have solvent accessible voids. By contrast, memantine hydrochloride which differs in the substitution of two methyl groups on the adamantane ring has a crystal energy landscape where all structures within 10 kJ mol−1of the global minimum have solvent-accessible voids ranging from 3 to 14% of the unit-cell volume including the lattice energy minimum that was calculated after removing water from the hydrated memantine hydrochloride salt structure. The success in using crystal structure prediction (CSP) to rationalize the different hydration propensities of these substituted adamantane hydrochloride salts allowed us to extend the model to predict under blind test conditions the experimental crystal structures of the previously uncharacterized 1-(methylamino)adamantane base and its corresponding hydrochloride salt. Although the crystal structure of 1-(methylamino)adamantane was correctly predicted as the second ranked structure on the static lattice energy landscape, the crystallization of aZ′ = 3 structure of 1-(methylamino)adamantane hydrochloride reveals the limits of applying CSP when the contents of the crystallographic asymmetric unit are unknown.

scholarly journals A third blind test of crystal structure prediction

2005 ◽  
Vol 61 (5) ◽  
pp. 511-527 ◽  
Author(s):  
G. M. Day ◽  
W. D. S. Motherwell ◽  
H. L. Ammon ◽  
S. X. M. Boerrigter ◽  
R. G. Della Valle ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Lattice Energy ◽  
Crystal Structure Prediction ◽  
Success Rates ◽  
Blind Test ◽  
Energy Models ◽  
Successful Prediction ◽  
Structure Report

Following the interest generated by two previous blind tests of crystal structure prediction (CSP1999 and CSP2001), a third such collaborative project (CSP2004) was hosted by the Cambridge Crystallographic Data Centre. A range of methodologies used in searching for and ranking the likelihood of predicted crystal structures is represented amongst the 18 participating research groups, although most are based on the global minimization of the lattice energy. Initially the participants were given molecular diagrams of three molecules and asked to submit three predictions for the most likely crystal structure of each. Unlike earlier blind tests, no restriction was placed on the possible space group of the target crystal structures. Furthermore, Z′ = 2 structures were allowed. Part-way through the test, a partial structure report was discovered for one of the molecules, which could no longer be considered a blind test. Hence, a second molecule from the same category (small, rigid with common atom types) was offered to the participants as a replacement. Success rates within the three submitted predictions were lower than in the previous tests – there was only one successful prediction for any of the three `blind' molecules. For the `simplest' rigid molecule, this lack of success is partly due to the observed structure crystallizing with two molecules in the asymmetric unit. As in the 2001 blind test, there was no success in predicting the structure of the flexible molecule. The results highlight the necessity for better energy models, capable of simultaneously describing conformational and packing energies with high accuracy. There is also a need for improvements in search procedures for crystals with more than one independent molecule, as well as for molecules with conformational flexibility. These are necessary requirements for the prediction of possible thermodynamically favoured polymorphs. Which of these are actually realised is also influenced by as yet insufficiently understood processes of nucleation and crystal growth.

Crystal structure prediction of small organic molecules: a second blind test

2002 ◽  
Vol 58 (4) ◽  
pp. 647-661 ◽  
Author(s):  
W. D. Sam Motherwell ◽  
Herman L. Ammon ◽  
Jack D. Dunitz ◽  
Alexander Dzyabchenko ◽  
Peter Erk ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Organic Molecules ◽  
Molecular Model ◽  
Objective Measure ◽  
Lattice Energy ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Space Groups ◽  
Common Space

The first collaborative workshop on crystal structure prediction (CSP1999) has been followed by a second workshop (CSP2001) held at the Cambridge Crystallographic Data Centre. The 17 participants were given only the chemical diagram for three organic molecules and were invited to test their prediction programs within a range of named common space groups. Several different computer programs were used, using the methodology wherein a molecular model is used to construct theoretical crystal structures in given space groups, and prediction is usually based on the minimum calculated lattice energy. A maximum of three predictions were allowed per molecule. The results showed two correct predictions for the first molecule, four for the second molecule and none for the third molecule (which had torsional flexibility). The correct structure was often present in the sorted low-energy lists from the participants but at a ranking position greater than three. The use of non-indexed powder diffraction data was investigated in a secondary test, after completion of the ab initio submissions. Although no one method can be said to be completely reliable, this workshop gives an objective measure of the success and failure of current methodologies.

scholarly journals Sixth blind test of organic crystal-structure prediction methods

2014 ◽  
Vol 70 (4) ◽  
pp. 776-777 ◽  
Author(s):  
Colin R. Groom ◽  
Anthony M. Reilly
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Organic Molecules ◽  
Prediction Methods ◽  
Crystal Structure Prediction ◽  
Cambridge Crystallographic Data Centre ◽  
Blind Test ◽  
Small Organic Molecules ◽  
Data Centre ◽  
The Past

Over the past 15 years progress in predicting crystal structures of small organic molecules has been charted by a series of blind tests hosted by the Cambridge Crystallographic Data Centre. This letter announces a sixth blind test to take place between September 2014 and August 2015, giving details of the target systems and the revised procedure. We hope that as many methods as possible will be assessed and benchmarked in this new blind test.

scholarly journals Significant progress in predicting the crystal structures of small organic molecules – a report on the fourth blind test

2009 ◽  
Vol 65 (2) ◽  
pp. 107-125 ◽  
Author(s):  
Graeme M. Day ◽  
Timothy G. Cooper ◽  
Aurora J. Cruz-Cabeza ◽  
Katarzyna E. Hejczyk ◽  
Herman L. Ammon ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Organic Molecules ◽  
Dramatic Improvement ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Collaborative Project ◽  
Small Organic Molecules ◽  
Modelling Methods

We report on the organization and outcome of the fourth blind test of crystal structure prediction, an international collaborative project organized to evaluate the present state in computational methods of predicting the crystal structures of small organic molecules. There were 14 research groups which took part, using a variety of methods to generate and rank the most likely crystal structures for four target systems: three single-component crystal structures and a 1:1 cocrystal. Participants were challenged to predict the crystal structures of the four systems, given only their molecular diagrams, while the recently determined but as-yet unpublished crystal structures were withheld by an independent referee. Three predictions were allowed for each system. The results demonstrate a dramatic improvement in rates of success over previous blind tests; in total, there were 13 successful predictions and, for each of the four targets, at least two groups correctly predicted the observed crystal structure. The successes include one participating group who correctly predicted all four crystal structures as their first ranked choice, albeit at a considerable computational expense. The results reflect important improvements in modelling methods and suggest that, at least for the small and fairly rigid types of molecules included in this blind test, such calculations can be constructively applied to help understand crystallization and polymorphism of organic molecules.

scholarly journals Towards crystal structure prediction of complex organic compounds – a report on the fifth blind test

2011 ◽  
Vol 67 (6) ◽  
pp. 535-551 ◽  
Author(s):  
David A. Bardwell ◽  
Claire S. Adjiman ◽  
Yelena A. Arnautova ◽  
Ekaterina Bartashevich ◽  
Stephan X. M. Boerrigter ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Density Functional ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Functional Theory ◽  
Flexible Molecule ◽  
Successful Prediction ◽  
The Many ◽  
Complex Organic

Following on from the success of the previous crystal structure prediction blind tests (CSP1999, CSP2001, CSP2004 and CSP2007), a fifth such collaborative project (CSP2010) was organized at the Cambridge Crystallographic Data Centre. A range of methodologies was used by the participating groups in order to evaluate the ability of the current computational methods to predict the crystal structures of the six organic molecules chosen as targets for this blind test. The first four targets, two rigid molecules, one semi-flexible molecule and a 1:1 salt, matched the criteria for the targets from CSP2007, while the last two targets belonged to two new challenging categories – a larger, much more flexible molecule and a hydrate with more than one polymorph. Each group submitted three predictions for each target it attempted. There was at least one successful prediction for each target, and two groups were able to successfully predict the structure of the large flexible molecule as their first place submission. The results show that while not as many groups successfully predicted the structures of the three smallest molecules as in CSP2007, there is now evidence that methodologies such as dispersion-corrected density functional theory (DFT-D) are able to reliably do so. The results also highlight the many challenges posed by more complex systems and show that there are still issues to be overcome.

scholarly journals Minimizing Polymorphic Risk Through Cooperative Computational and Experimental Exploration

2020 ◽  
Author(s):  
Christopher R. Taylor ◽  
Matthew T. Mulvee ◽  
Domonkos S. Perenyi ◽  
Michael R. Probert ◽  
Graeme Day ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Structure Prediction ◽  
Experimental Approach ◽  
Significant Risk ◽  
Free Energy Calculations ◽  
Crystal Structure Prediction ◽  
Crystal Forms ◽  
Wide Range ◽  
Solid Form

<div> <p>We combine state-of-the-art computational crystal structure prediction (CSP) techniques with a wide range of experimental crystallization methods to understand and explore crystal structure in pharmaceuticals and minimize the risk of unanticipated late-appearing polymorphs. Initially, we demonstrate the power of CSP to rationalize the difficulty in obtaining polymorphs of the well-known pharmaceutical isoniazid and show that CSP provides the structure of the recently discovered, but unsolved, Form III of this drug despite there being only a single known form for almost 70 years. More dramatically, our blind CSP study predicts a significant risk of polymorphism for the related iproniazid. Employing a wide variety of experimental techniques, including high-pressure experiments, we experimentally obtained the first three known non-solvated crystal forms of iproniazid, all of which were successfully predicted in the CSP procedure. We demonstrate the power of CSP methods and free energy calculations to rationalize the observed elusiveness of the third form of iproniazid, the success of high-pressure experiments in obtaining it, and the ability of our synergistic computational-experimental approach to “de-risk” solid form landscapes.</p> </div>

scholarly journals Report on the sixth blind test of organic crystal structure prediction methods

2016 ◽  
Vol 72 (4) ◽  
pp. 439-459 ◽  
Author(s):  
Anthony M. Reilly ◽  
Richard I. Cooper ◽  
Claire S. Adjiman ◽  
Saswata Bhattacharya ◽  
A. Daniel Boese ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Density Functional ◽  
Organic Crystal ◽  
Drug Candidate ◽  
Prediction Methods ◽  
Chloride Salt ◽  
Crystal Structure Prediction ◽  
Blind Test ◽  
Flexible Molecules

The sixth blind test of organic crystal structure prediction (CSP) methods has been held, with five target systems: a small nearly rigid molecule, a polymorphic former drug candidate, a chloride salt hydrate, a co-crystal and a bulky flexible molecule. This blind test has seen substantial growth in the number of participants, with the broad range of prediction methods giving a unique insight into the state of the art in the field. Significant progress has been seen in treating flexible molecules, usage of hierarchical approaches to ranking structures, the application of density-functional approximations, and the establishment of new workflows and `best practices' for performing CSP calculations. All of the targets, apart from a single potentially disorderedZ′ = 2 polymorph of the drug candidate, were predicted by at least one submission. Despite many remaining challenges, it is clear that CSP methods are becoming more applicable to a wider range of real systems, including salts, hydrates and larger flexible molecules. The results also highlight the potential for CSP calculations to complement and augment experimental studies of organic solid forms.

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