Tunable Multicolor Phosphorescence of Crystalline Polymeric Complex Salts with Metallophilic Backbones

A total of 35 [Au(NHC)₂ ][MX₂ ] (NHC=N-heterocyclic carbene; M=Au or Cu; X=halide, cyanide or arylacetylide) complex salts were synthesized by co-precipitation of [Au(NHC)₂ ]⁺ cations and [MX₂ ]^- anions. These salts contain crystallographically determined polymeric Au⋅⋅⋅Au or Au⋅⋅⋅Cu interactions and are highly phosphorescent with quantum yields up to unity and emission color tunable in the entire visible regions. The nature of the emissive excited states is generally assigned to ligand (anion)-to-ligand (cation) charge-transfer transitions assisted by d¹⁰ ⋅⋅⋅d¹⁰ metallophilicity. The emission properties can be further tuned by controlled triple-component co-crystallization or by epitaxial growth. Correct recipes for white light-emitting phosphors with quantum yields higher than 70 % have been achieved by screening the combinatorial pool.