Andrew V. Trask

Solvent-drop grinding: green polymorph control of cocrystallisationElectronic supplementary information (ESI) available: additional powder XRD patterns. See http://www.rsc.org/suppdata/cc/b4/b400978a/

By grinding with a minimal addition of a solvent of appropriate polarity, control over the polymorphic outcome of a novel cocrystallisation involving the model pharmaceutical compound caffeine may be achieved.

Screening for crystalline salts via mechanochemistry

Neat grinding and solvent-drop grinding methods are found to be effective screening tools for indicating the potential for crystalline salt formation involving a given acid-base pair, as demonstrated with two model pharmaceuticals.

Investigating the latent polymorphism of maleic acid

The unexpected appearance of a new polymorph of maleic acid is reported and a computational study addresses the predictability of this new polymorph and future potential polymorphism.

Selective polymorph transformation via solvent-drop grinding.

A method of inducing specific polymorph transformations is exemplified with two single-component systems, whereby a given crystal form undergoes conversion when subjected to solid state grinding in the presence of a minor quantity of a certain solvent.

The crystal structure of an unstable polymorph of β-D-allose

The crystal structure of a new polymorph, Form II, of β-D-allose has been determined by X-ray powder diffraction. The unit cell is hexagonal, a = b = 16.598 A, c = 4.856 A, α = β = 90°, γ = 120°, space group P62 with Z = 6, Z′ = 1. The molecule adopts the 4C1 chair-conformation, with a torsional change of conformation of the O6 side-chain compared to the orthorhombic Form I. The two polymorphs share a common feature of a stacked hydrogen bonded column of molecules in the short axis direction. The structures differ in hydrogen linking of these columns. The more stable Form I has more immediate neighbours linked by hydrogen bonds to a reference molecule, and higher crystal density than Form II.