Searching for novel crystal forms by in situ high-pressure crystallisation: the example of gabapentin heptahydrate

High-pressure crystallisation of an aqueous solution of the GABA analogue gabapentin at 0.8 GPa resulted in the formation of a previously unknown heptahydrate form, whose structure has been determined by in situ single-crystal X-ray diffraction. The structure and water framework of this unusually highly hydrated small molecule are described in detail.