Chromic triboluminescence of self-assembled platinum(II) complexes.

A series of Pt(II) complexes bearing N-heterocyclic carbenes, [Pt(CN)2(Rim-Mepy)] (Rim-MepyH+ = 3-alkyl-1-(4-methyl-(2-pyridinyl))-1H-imidazolium, R = Me, Et, iPr, or tBu), exhibits triboluminescence in the visible range from blue to red, as well as the corresponding intense photoluminescence. Remarkably, among the complexes, the iPr-substituted one exhibits chromic triboluminescence behaviour during the process of rubbing and also vapour exposure.