Platinum–ethynylflavone complexes featuring various polyether arms display ³IL phosphorescence associated with the appended flavone perturbed by the platinum centre (τ ∼20 μs), but switch dramatically to flavone-localised ¹IL fluorescence (τ ∼ 2 ns) upon selective binding of Pb²⁺.

Luminescent dinuclear Ir(iii) complexes of a bis-N^∧C^∧N-coordinating ligand are reported with two metal ions bound to a central pyrimidine. A pair of enantiomers and a meso form have been structurally characterised.

We present the synthesis and in-depth photophysical analysis of a di-Pt(II) complex with a ditopic bis-N^C^N ligand. The complex exhibits a dual luminescent behaviour by emitting simultaneously delayed fluorescence and phosphorescence. By comparing with the mono-Pt(II) analogue, we demonstrate that thermally activated delayed fluorescence (TADF) is turned on in the di-Pt(II) complex due to the occurrence of three main differences relative to the mono-Pt(II) analogue: a larger singlet radiative rate constant (k^S _r), a smaller singlet–triplet energy gap (ΔE_ST) and a longer phosphorescence decay lifetime (τ_PH). We observe similar trends among other di-Pt(II) complexes and conclude that bimetallic structures promote conditions favourable for TADF to occur. The diplatinum(II) complex also shows a long wavelength-emissive excimer which yields near infrared electroluminescence, λ_el = 805 nm, in a solution-processed OLED device with EQE_max = 0.51%. We believe this is the highest efficiency reported to date for an excimer Pt(II) emitter with λ_el > 800 nm in a solution-processed OLED device.

The design, synthesis, photophysical properties, and the ion-binding properties of cyclometallated platinum(II) complexes containing pyridyl-appended alkynyl ligands are described. When the pyridyl group is incorporated into an azamacrocycle, a specific response towards lead(II) cations involves a change in the nature of the excited charge transfer state, resulting in the appearance of a low-energy absorption band and a partial quenching of luminescence.