Sterically Hindered Luminescent Pt-II-Phosphite Complexes for Electroluminescent Devices

PtII complexes with one bulky, sterically demanding, tertiary phosphite ancillary ligand and a coordinating chromophore are herein presented. The phosphite ligand, tris(2,4-di-tert-butylphenyl) acts as a bidentate ligand coordinating the platinum ion through the central phosphorus atom and a cyclometalating carbon atom of one of the substituents. The two free phenoxy moieties lie above and below the coordination plane, leading to steric hindrance that avoids aggregation and provides solubility in organic solvents. The other two coordination sites on the central metal ion are occupied by a chromophoric ligand, which is responsible for the energy of the luminescent excited state. This separation of functions, on the two coordinated ligands, allows the use of a wider range of luminophores with good luminescent properties, maintaining the control of the intermolecular interactions with the non-chromophoric ligand. Based on this approach we were able to achieve a bright deep blue emission (\u3bb= 444 nm, \u3a6em=0.38) from a complex with a tailored ligand, which was then used for the fabrication of an electroluminescent device. In addition commercially available luminophores were also employed to synthesize green emitters

Heteroleptic, Dinuclear Copper(I) Complexes for Application in Organic Light-Emitting Diodes

A series of highly luminescent, heteroleptic copper­(I) complexes has been synthesized using a modular approach based on easily accessible P^N ligands, triphenylphosphine, and copper­(I) halides, allowing for an independent tuning of the emission wavelength with low synthetic efforts. The molecular structure has been investigated via X-ray analysis, confirming a dinuclear copper­(I) complex consisting of a butterfly shaped metal-halide cluster and two different sets of ligands. The bidentate P^N ligand bridges the two metal centers and can be used to tune the energy of the frontier orbitals and therefore the photophysical characteristics, as confirmed by emission spectroscopy and theoretical investigations, whereas the two monodentate triphenylphosphine ligands on the periphery of the cluster core mainly influence the solubility of the complex. By using electron-rich or electron-poor heterocycles as part of the bridging ligand, emission colors can be adjusted, respectively, between yellow (581 nm) and deep blue (451 nm). These complexes have been further investigated in particular with regard to their photophysical properties in thin films and polymer matrix as well as in solution. Furthermore, the suitability of this class of materials for being applied in organic light-emitting diodes (OLEDs) has been demonstrated in a solution-processed device with a maximum current efficiency of 9 cd/A and a low turn-on voltage of 4.1 V using a representative complex as an emitting compound

Triazoles from N-alkynylheterocycles and their coordination to iridium

N-alkynylheterocycles (benzimidazole and indazole) are converted to triazoles by click chemistry, and the resulting triazoles react with [IrCl2Cp*]2. The benzimidazole-triazole coordinates in a monodentate fashion through the benzimidazole, whereas the indazole-triazole is bidentate through coordination of both heterocycles. Reaction of the benzimidazole-triazole with methyliodide gives a benzimidazolium salt that deprotonates on coordination to afford a rare example of a bidentate NHC–triazole