Design of (NHC) Copper(I) complexes bearing dipyridylamine ligands for application in luminescent materials: (NHC) Cu(I) Complexes bearing Dipyridylamine ligands - Synthesis, Structural, Photoluminescent Studies and Applications in Luminescent Materials

Abstract : We present in this communication the synthesis of new cationic tricoordinated copper complexes bearing bidentate dipyridylamine (dpa) ligands and NHC as ancillary ligands [Cu(NHC)(HDPA)][X].(1,2) These copper complexes have been fully characterized by NMR, X-ray analysis, electrochemistry, and photophysics. TD-DFT calculations were also undergoneto rationalize the assignment of the photophysical properties. Some of these copper complexes exhibit very bright blue emission with high quantum yield at solid state. A variation of the electronic properties on both NHC and dipyridylamine ligands, has been carried out and permitted to establish a structure – properties relationship, also supported by TD-DFT calculations. A photophysical study at low temperature highlighted a specific luminescence phenomenon of the complexes: Thermally Activated Delayed Flurorescence. Since emissive cationic organometallic complexes can be good candidates for LEC (Light emittingElectrochemical Cells) applications, a selection of copper complexes was achieved for the preparation of those lighting devices. Here is presented the proof of concept that our copper complexes, of general formula [Cu(NHC)(dpa)][X], can be applied for LEC devices. To the best of our knowledge, we are presenting here the first blue emitting LEC device incorporating cationic copper complexes.