Crystals reach new heights

Crystals of a cobalt complex can jump 10,000 times their height when exposed to light. Now, a team from Japan and Russia has come up with an explanation for this bizarre behavior. The crystals’ rapid movement is a result of stresses generated in the crystal when light induces a structural change within it, according to Elena Boldyreva of Novosibirsk State University and her colleagues. Light triggers an isomerization that forces a nitrite group in the complex to switch from being bonded through a nitrogen atom to an oxygen atom. This internal structural change generates a stress perpendicular to the original isomer's crystal structure which is then released as the crystals crack apart violently.