Counteranion‐Dependent Luminescence in Crystalline and Supercooled Liquid States of Liquescent Cationic Gold(I) Complexes

Cationic gold(I) complexes bearing cyclohexylisocyanide ligands with different counteranions, 1 ⁺ ·NTf ₂ ⁻ [NTf ₂ ⁻ : bis(trifluoromethanesulfonyl)imide ion], 1 ⁺ ·OTf ⁻ (OTf ⁻ : trifluoromethanesulfonate ion), and 1 ⁺ ·SbF ₆ ⁻ , exhibited counteranion‐dependent luminescence in both crystalline and supercooled liquid states. In the crystalline state at 298 K, the complexes showed intense luminescence with emission maxima ranging from 461 to 505 nm depending on the counteranion. Upon heating above their melting points [41 °C (314 K) for 1 ⁺ ·NTf ₂ ⁻ , 67 °C (340 K) 1 ⁺ ·OTf ⁻ , and 114 °C (387 K) for 1 ⁺ ·SbF ₆ ⁻ ], the luminescence was almost completely quenched. Cooling of the molten samples generated emissive supercooled liquid phases that persisted at room temperature for more than 1 h. Notably, the supercooled liquids also exhibited distinct emission colors and wavelengths depending on the counteranion. Single‐crystal X‐ray diffraction analyses revealed one‐dimensional aggregation structures with short intermolecular Au(I)–Au(I) contacts, whose distances varied with the counteranion. The emission wavelengths correlated with the Au(I)–Au(I) distances, indicating that counteranion‐controlled metallophilic interactions govern the luminescent properties.