Mono-/Bimetallic Neutral Iridium(III) Complexes Bearing Diketopyrrolopyrrole-Substituted N-Heterocyclic Carbene Ligands: Synthesis and Photophysics

Abstract

The synthesis and photophysics (UV–vis absorption, emission, and transient absorption) of four neutral heteroleptic cyclometalated iridium­(III) complexes (Ir-1–Ir-4) incorporating thiophene/selenophene-diketopyrrolopyrrole (DPP)-substituted N-heterocyclic carbene (NHC) ancillary ligands are reported. The effects of thiophene versus selenophene substitution on DPP and bis- versus monoiridium­(III) complexation on the photophysics of these complexes were systematically investigated via spectroscopic techniques and density functional theory calculations. All complexes exhibited strong vibronically resolved absorption in the regions of 500–700 nm and fluorescence at 600–770 nm, and both are predominantly originated from the DPP-NHC ligand. Complexation induced a pronounced red shift of this low-energy absorption band and the fluorescence band with respect to their corresponding ligands due to the improved planarity and extended π-conjugation in the DPP-NHC ligand. Replacing the thiophene units by selenophenes and/or biscomplexation led to the red-shifted absorption and fluorescence spectra, accompanied by the reduced fluorescence lifetime and quantum yield and enhanced population of the triplet excited states, as reflected by the stronger triplet excited-state absorption and singlet oxygen generation.

Doubly 1,3-butadiyne-bridged ditwistacene with enhanced ultrafast broadband reverse saturable absorption

“…3, the captured curves show that the positive signals cover a very broad spectral region from 470 nm to 1050 nm, which is among the widest ESA spectra reported for organic OPL materials. [48][49][50] All ESA signals decay monotonously without any changes in the peak profile, such as the generation of new peaks and spectral shifts, which indicates that the dynamic behavior is of singlet ESA species without the presence of other transition processes, such as intramolecular charge transfer (ICT), charge separation and inter-system crossing (ISC). 51 The dynamic traces would be successfully fitted biexponentially through the global analysis method (corresponding fitted traces are shown in Fig.…”

The design and synthesis of green emissive iridium(iii) complexes guided by calculations of the vibrationally-resolved emission spectra

“…[28][29][30][31][32] Several studies have demonstrated good correlation between experimental and simulated emission spectra of existing iridium-and platinum-containing emitters, 29,[33][34][35] but there are very few reports containing vibrational studies that are used as a tool for the design of new complexes. 9,[36][37][38] With a view to obtaining improved colour green emitters, here we modelled the vibrationally-coupled emission spectra, of a family of trimethylsilane-substituted green-emissive iridium complexes and then correlated these findings to their photophysical properties.…”

“…28–32 Several studies have demonstrated good correlation between experimental and simulated emission spectra of existing iridium- and platinum- containing emitters, 29,33–35 but there are very few reports containing vibrational studies that are used as a tool for the design of new complexes. 9,36–38…”

The design and synthesis of green emissive iridium(III) complexes guided by calculations of the vibrationally-resolved emission spectra

“…[28][29][30][31][32] Several studies have demonstrated good correlation between experimental and simulated emission spectra of existing iridium-and platinum-containing emitters, 29,[33][34][35] but there are very few reports containing vibrational studies that are used as a tool for the design of new complexes. 9,[36][37][38] With a view to obtaining improved colour green emitters, here we modelled the vibrationally-coupled emission spectra, of a family of trimethylsilane-substituted greenemissive iridium complexes and then correlated these findings to their photophysical properties.…”