Reversible piezochromism in a molecular wine-rack
E L Harty, A R Ha, M R Warren, A L Thompson, D Allan, A L Goodwin, and N P Funnell
Chem Comm 51, 10608 (2015)

The highly-polymorphic, strongly-coloured ‘ROY’ system exhibits a yellow→orange→red piezochromic response under hydrostatic compression. The ‘Y’ (yellow) polymorph accommodates the effect of pressure via a wine-rack-type mechanism, made accessible by the conformational flexibility of the molecule, all while retaining the crystal symmetry of the parent Y form. Decompression from 1.49 GPa demonstrates reversibility of this behaviour.