Certain salt crystals are normally cube-shaped, but can take on a new shape and grow on the surface of tiny water droplets.

Zhongping Zhang, Suhua Wang and their colleagues at the Chinese Academy of Sciences in Hefei mixed a water-based solution of either sodium chloride or potassium chloride with cyclohexane and acetone. After shaking, hollow spheres formed that were made up of individual 'hopper-like' crystals of the salt (pictured). The spheres probably formed at the interface between the organic solvents and the water droplets that contained the salt.

Credit: WILEY-VCH

The technique may produce new crystal structures for other water-soluble compounds, and could aid in understanding crystal growth mechanisms, the authors suggest.

Angew. Chem. Int. Edn doi:10.1002/anie.201101704 (2011)