Trinuclear gold(I) triazolates: A new class of wide-band phosphors and sensors

A new cyclic gold(I) triazolate trimer, [Au(3,5-i-Pr₂Tz)] ₃ (1), exhibits fully overlapping aurophilically bonded dimer-of-trimer units that lead to multiple phosphorescence bands in both the solid state and solution. The conformation of the hexanuclear unit exhibits reversible interconversion between C₂ and D₃ effective symmetries, depending on the crystal temperature or solution concentration, the variation of which leads to isoemissive and isosbestic points. Solutions of 1 exhibit remarkable quenching properties that demonstrate molecular recognition with high selectivity and hypersensitivity for some reagents, as influenced by protonation via Brønsted acids, π intercalation, and/or energy transfer. The quenched phosphorescence of 1 by acetic acids can be regenerated by NEt₃.