Au13 Superatom Bearing Two Terpyridines at Coaxial Positions: Photoluminescence Quenching via Complexation with 3d Metal Ions

A gold cluster [Au13(dppe)5(EPTpy)2]3+ (dppe = 1,2-bis(di-phenylphosphino)ethane, EPTpy-H = 4'-(4-ethynylphenyl)-2,2':6',2''-terpyridine) was synthesized by ligand exchange reaction of [Au13(dppe)5Cl2]3+. Single-crystal X-ray diffraction analysis revealed that two terpyridyl moieties were sigma-bonded to the coaxial positions of the icosahedral Au13 core. These two terpyridyl moieties were coordinated with 3d metal ions M2+ (M = Co, Ni, Cu, Zn) in acetonitrile solution under ambient conditions. The photoluminescence (PL) of [Au13(dppe)5- (EPTpy)2]3+ with a quantum yield of 0.17 at 3780 nm was almost completely quenched by coordination with Co2+, Ni2+, and Cu2+, while the PL was not affected by Zn2+ coordination. The metal-dependent PL quenching behavior is ascribed to the difference in the electronic structure of the metal ions. The energy transfer from the Au13 chromophore to the coordinated Co2+, Ni2+, or Cu2+ with an open electronic structure proceeds efficiently via an electron exchange mechanism, while the proc-ess is prohibited for Zn2+ with a closed electronic structure.

Automated summary

A gold cluster with terpyridyl ligands was synthesized and its coordination behavior with different metal ions was investigated. The photoluminescence of the gold cluster was found to be affected differently by different metal ions, depending on their electronic structures. These findings are important for understanding the optical properties and applications of gold clusters.