Communication pubs.acs.org/Organometallics
A New Framework of a Heteroleptic Iridium(III)−Carbene Complex as a Triplet Emitting Material Björn Wiegmann,† Peter G. Jones,‡ Gerhard Wagenblast,§ Christian Lennartz,§ Ingo Münster,§ Stefan Metz,§ Wolfgang Kowalsky,† and Hans-Hermann Johannes*,† †
Institut für Hochfrequenztechnik, Technische Universität Braunschweig, Schleinitzstraße 22, 38106 Braunschweig, Germany Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany § BASF SE, 67056 Ludwigshafen, Germany ‡
S Supporting Information *
ABSTRACT: A new framework for a dark red emitting heteroleptic failed cyclometalated iridium(III) carbene complex as an intermediate with a short triplet lifetime has been synthesized. A crystal structure has been determined by X-ray structure analysis. The photophysical behavior of this complex has been studied experimentally through UV−vis spectroscopy and photoluminescence studies with a view toward organic light-emitting diode (OLED) applications. The determination of HOMO/LUMO levels has been carried out by differential pulse voltammetry.
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reagent is a common method for transmetalation, because (a) no additional base is needed, (b) deprotonation usually takes place at the carbene C2, and (c) the tolerance of Ag2O to other active hydrogen atoms is comparatively high.16−19 First the carbene precursor was synthesized as the imidazolium iodide salt 3 by nucleophilic aromatic substitution of 4-fluoro-1-naphthonitrile (1) with imidazole to form 4-(1Himidazol-1-yl)-1-naphthonitrile (2) followed by alkylation with methyl iodide, as depicted in Scheme 1. Afterward the Ag(I)− NHC complex 4 was generated by in situ deprotonation with the silver-containing base Ag2O in 73% overall yield.
ver the last two decades organometallic complexes containing third-row transition-metal ions, especially iridium(III), have been extensively studied with respect to their superior phosphorescence performance in organic lightemitting diode (OLED) applications.1−5 For solid-state lighting applications three-color white OLEDs are needed to generate a satisfying color rendering index (CRI). This can be achieved by combining highly efficient deep blue, green, and red phosphors with high quantum yields and very short luminescence decays (
