Reversible tricolour luminescence switching based on a piezochromic iridium(iii) complex.

On the basis of rational molecular design, the tricolour luminescence switching of an Ir(iii) complex is achieved for the first time. The transformation between two crystalline states and an amorphous state is responsible for the switching behaviour of this complex between blue, green and yellow states. Solvent molecules are shown to play a crucial role in the crystallization and luminescence processes.