Truly prospective prediction: inter- and intramolecular hydrogen bonding

Accurately predicting which H-bonds might form in an organic crystal structure is demonstrated in a prospective, chronological setting using our recently developed method. The extent of correct classification for present and absent H-bonds is assessed whereby training and trial data are separated on the basis of age; the choice of cut-off is termed the model date. An encouragingly high predictivity is maintained for H-bonds in target structures published over the last 7–8 years, indicating promising future application toward novel structures. Predictions are computed using probability models trained for chosen target compounds using existing crystal structures in the public domain. An extension to the prediction of intramolecular H-bonds is also applied and is seen to be significant when considering the combination of possible H-bonds for target structures. Two target systems are selected for illustration: an amino-chloride salt hydrate and an amido-carboxylic acid.