Triplet State Formation in Homo- and Heterometallic Diketopyrrolopyrrole Chromophores

Abstract

The synthesis, structural characterization, and excited-state dynamics of series of diketopyrrolopyrrole (DPP) bridged homodinuclear Ir­(III) and heterodinuclear Ir­(III)/Pt­(II) complexes is described. Steady-state and time-resolved photoluminescence along with transient absorption measurements were used to probe the nature of the emissive and long-lived excited states. Upon excitation into the ¹DPP ligand-localized excited state in the presence of coordinated Ir­(III) or Pt­(II) metal centers, the intersystem crossing is enhanced, leading to a quenching of the ¹DPP fluorescence and the formation of the long-lived (τ ≈ 30–40 μs) ³DPP excited state in all instances