Monocyclometalated (C N) Gold(III) Metallacycles: Tunable Emission and Singlet Oxygen (1O2) Generation Properties. Issue 58 (8th September 2021)

• Record Type: Journal Article
• Authors: Malmberg, Robert; Suter, Dominik; Blacque, Olivier; Venkatesan, Koushik
• Is Part Of: Chemistry. Volume 27:Issue 58(2021)
• Page Start: 14410
• Page End: 14417
• Publication Date: 2021-09-08
• Subjects: cyclometallation -- gold -- luminescence -- sensitizer -- singlet oxygen; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202102331
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The synthesis, characterization and photoluminescent properties of four cyclometalated (C N)‐type gold(III) complexes bearing a bidentate diacetylide ligand, tolan‐2, 2'‐diacetylide (tda), are reported. The complexes exhibit highly tunable excited state properties and show photoluminescence (PL) across the entire visible spectrum from sky‐blue (λPL =493 nm) to red (λPL =675 nm) with absolute PL quantum yields (PLQY) of up to 75 % in solution, the highest PLQY found for any monocyclometalated Au(III) complex in solution. As a consequence of the use of the strongly rigidifying diacetylide bidentate ligand, a significant increase in the excited state lifetimes (τ0 =16–258 μs) was found in solution and in thin films. The complexes showed remarkable singlet oxygen generation in aerated solution with absolute singlet oxygen quantum yield (ϕ 1Δ ) values reaching up to 7.5×10 −5 and singlet oxygen lifetimes (τ0 1Δ ) in the range of 66–95 μs. Furthermore, the radiative and non‐radiative rates of singlet oxygen were determined using the ϕ 1Δ and τ0 1Δ values and correlations are drawn between the formation of singlet oxygen and its interaction with cyclometalated (C N) gold(III) complexes. Abstract : Gold(III) metallacycles . Monocyclometalated gold(III) metallacycles with tunable emission properties have been demonstrated. The complexes show highly emissive triplet excited states (T1 ) with long excited state lifetimes. The T1 of the complexes and the triplet excited state of dioxygen ( 3 O2 ) lie in a delicate balance resulting in an efficient quenching of these triplet states to generate 1 O2 . The first use case of monocyclometalated gold(III) complexes to generate 1 O2 photochemically is demonstrated.