Resolution of the high-pressure phase of Hydrochlorothiazide

Hydrochlorothiazide (HCT) exhibits pressure-induced polymorphism. The new high-pressure form can be accessed above 0.8 GPa. During this reconstructive phase transition, the single crystal turns to a powder that is exhibits extremely insolubility. Our usual methods to anneal into a single crystal, via heat treating a solution of hydrochlorothiazide, have failed due to the apparent steep pressure-dependent solubility. We are able to recover the phase, however the powder diffraction pattern is a mixed phase with the known form. We have previously been allocated beamtime (CH6625) for this study that enabled us to explore the conditions in the press to be able to provide the best dataset for structural solution and refinement. This has been challenging due to the large strain in the sample over the transition. The set of parameters that we have found will provide our best opportunity to solve the structure of this simple yet intriguing solid.