Revisiting an ancient inorganic aggregation-induced emission system: An enlightenment to clusteroluminescence

Organic and inorganic clusteroluminescence have attracted great attention while the underlying mechanisms is still not well understood. Here, we employed a series of ancient inorganic complexes platinocyanides with aggregation-induced emission property to elucidate the mechanism of clusteroluminescence including how does the chromophore form and how does the solid structures influence the luminescence behaviors. The results indicate that the isolated platinocyanide cannot work as a chromophore to emit visible light, while their clusterization at aggregate state can trigger the d-orbitals coupling of the platinum atoms to facilitate the electron exchange and delocalization to form a new chromophore to emit visible light. Furthermore, the counter ions and H2O ligands help to rigidify the three-dimensional network structure of the platinocyanides to suppress the excited state nonradiative decay, resulting in the high quantum yield of up to 96%. This work fundamentally helps understanding both the organic and inorganic clusteroluminescence phenomenon.