Dynamic crystals: visually detected mechanochemical changes in the luminescence of gold and other transition-metal complexes.

Back to the grindstone: Certain crystalline complexes of gold, platinum, and vanadium undergo dramatic changes in their luminescence or their color upon grinding. The picture shows the transformation of colorless crystals of [(F(5)C(6)Au)(2)(mu-1,4-CN(2)C(6)H(4))] powder from a blue-emitting form (lambda(max) = 415 nm) to a yellow/green-emitting form (lambda(max) = 533 nm) on grinding with a pestle. The process is reversible.