Since 1999, the CCDC has held six “blind tests” of organic crystal-structure prediction methods.

Starting from an invitation-only workshop for structure prediction, the blind tests have grown to be an open and international collaborative effort to chart the progress and state of the art in predicting the crystal structures of small organic molecules.

Learn more about past CCDC CSP Blind Tests and the papers arising from them below. 

 

Sixth CSP Blind Test - 2015

The sixth blind test ended in August 2015 and was the biggest to date, with 25 different submissions and over 90 researchers involved. The five target systems were a small relatively rigid molecule, a former drug candidate, with five known but unpublished polymorphs, a salt hydrate, a co-crystal, and the largest molecule in a blind test to date. All of the target systems were predicted, apart from a single Z’ = 2 polymorph of the drug candidate. Overall, the results are encouraging for the development and maturity of CSP methods, which are now applicable to larger molecules and more complex solid forms such as hydrates and salts.

The full results of the sixth blind test are published in a special issue of Acta Cryst. B.  For more details about the sixth blind test, or to register interest in any future tests, please contact Jason Cole at the CCDC.

Target XXIV in the six blind test of organic CSP methods, which is a chloride salt hydrate of (Z)-3-((diaminomethyl)thio)acrylic acid.

 

Publications from the Sixth CCDC Crystal Structure Prediction Blind-Test

  • Report on the sixth blind test of organic crystal structure prediction methods.
    A.M. Reilly et al. Acta Cryst. B72, 439-459, 2016 10.1107/S2052520616007447

 

Fifth CSP Blind Test - 2010

The fifth blind test ran in 2010 with the final summary report published in 2011. The test included a variety of targets, from rigid and semi-flexible molecules, to a 1:1 salt, as well as a larger more flexible molecule and a hydrate with multiple polymorphs. While there were fewer successful results than previous years, there was at least one successful result for each target. The results also showed the progress made in methodologies such as dispersion-corrected density functional theory (DFT-D) which has become much more reliable.

Target XX in the fifth CSP Blind Test - a highly flexible compound with eight exocyclic torsion angles. Benzyl-(4-(4-methyl-5-(p-tolylsulfonyl)-1,3-thiazol-2-yl)phenyl)carbamate (C25H22N2O4S2)

 

Read more in the summary report; Towards crystal structure prediction of complex organic compounds - a report on the fifth blind test. D. Bardwell, et al, Acta Cryst. B67, 535-551, 10.1107/S0108768111042868

 

Fourth CSP Blind Test - 2007

The fourth blind test started in 2007, with 14 research groups taking part. Across the four targets, we saw a dramatic improvement in successful predictions compared to previous tests. This reflects important improvements in methods and suggest that for small and rigid molecules calculations are able to aid understanding in crystallization and polymorphism of organic molecules.

Molecule XIV from the fourth CSP Blind Test - N-(Dimethylthiocarbamoyl)benzo­thiazole-2-thione (C10N10N2S3)

 

Read more in the summary paper; Significant progress in predicting the crystal structures of small organic molecules – a report on the fourth blind test. G. Day, et al, Acta Cryst. B65, 107-125, 10.1107/S0108768109004066

 

Third CSP Blind Test - 2004

In the third CSP blind test a range of methods were employed by the 18 participating research groups. Most were based on the global minimization of lattice energy. Three targets were provided, with no restriction on the possible space group - unlike previous tests.

The test saw lower success rates than previous ones, in part due to complexities in some of the targets. This highlights the need for better energy models which can describe conformational and packing energies with high accuracy.

Molecule XI from the third CSP Blind Test - Azetidine. With several possible arrangements for hydrogen bonding, the crystal structure is built up from chains containing two azetidine molecules in the asymmetric unit.

 

Read more in the summary paper; A third blind test of crystal structure prediction. G. Day. et al, Acta Cryst. B61, 511-527, 10.1107/S0108768105016563

 

Second CSP Blind Test - 2001

The second CSP Blind Test saw 17 participants predict the crystal structure of three organic molecules. A maximum of three predictions were allowed for each molecule, with many correct predictions observed. A secondary test using non-indexed powder diffraction data was performed after submissions.

Read more in the summary paper; Crystal structure prediction of small organic molecules: a second blind test. W. D. S. Motherwell. et al, Acta Cryst. B58, 647-661, 10.1107/S0108768102005669

 

First CSP Blind Test - 1999

A collaborative workshop was held to test how well current methods of crystal structure prediction perform. The 11 participants were presented with the molecular structure of four compounds, which had been experimentally determined but as-yet unpublished. None of the methods gave consistently reliable results, but many proposed structures were close to the experimentally observed one. One target compound was observed to have two polymorphs, but only one form was predicted correctly.

Read more in the summary report; A test of crystal structure prediction of small organic molecules. J. P. M. Lommerse. et alActa Cryst. B56, 697-714, 10.1107/S0108768100004584