Triphenylene Chromophore Enhances Emission in Au/Cu Heterometallic Complexes

Abstract

Heterometallic Au(I)–Cu(I) assemblies are attractive luminescent platforms due to synergistic metallophilic interactions and enhanced spin–orbit coupling. We report a new family of Au(I)–Cu(I) complexes incorporating a rigid 2-ethynyltriphenylene chromophore and a pyridyldiphenylphosphine auxiliary ligand. Stoichiometric reactions between a mononuclear alkynyl gold(I) precursor and Cu(I) salts bearing different counterions (PF₆⁻, OTf⁻, BF₄⁻) afford Au₂Cu₂ assemblies whose structures and packing are strongly counterion-dependent. Single-crystal X-ray diffraction reveals Au–Cu interactions supported by Cu–N(pyridyl) and Cu···π(alkynyl) contacts. The photophysical studies show counterion-modulated dual fluorescence/phosphorescence emission in solution, with phosphorescence enhanced under inert conditions. Upon immobilization in polymer matrices, all heterometallic complexes display efficient room-temperature phosphorescence with quantum yields up to 40% and millisecond lifetimes. These results highlight the role of counterions and matrix rigidification in controlling excited-state deactivation in heterometallic coinage-metal systems.