A series of copper(I) complexes of the type [Cu(HN‐xantphos)(N^N)][PF6] and [Cu(BnN‐xantphos)(N^N)][PF6], in which N^N = bpy, Mebpy, and Me2bpy, HN‐xantphos = 4,6‐bis(diphenylphosphanyl)‐10H‐phenoxazine and BnN‐xantphos = 10‐benzyl‐4,6‐bis(diphenylphosphanyl)‐10H‐phenoxazine is described. The single crystal structures of [Cu(HN‐xantphos)(Mebpy)][PF6] and [Cu(BnN‐xantphos)(Me2bpy)][PF6] confirm the presence of N^N and P^P chelating ligands with the copper(I) atoms in distorted coordination environments. Solution electrochemical and photophysical properties of the BnN‐xantphos‐containing compounds (for which the highest‐occupied molecular orbital is located on the phenoxazine moiety) are reported. The first oxidation of [Cu(BnN‐xantphos)(N^N)][PF6] occurs on the BnN‐xantphos ligand. Time‐dependent density functional theory (TD‐DFT) calculations have been used to analyze the solution absorption spectra of the [Cu(BnN‐xantphos)(N^N)][PF6] compounds. In the solid‐state, the compounds show photoluminescence in the range 518–555 nm for [Cu(HN‐xantphos)(N^N)][PF6] and 520–575 nm for [Cu(BnN‐xantphos)(N^N)][PF6] with a blue‐shift on going from bpy to Mebpy to Me2bpy. [Cu(BnN‐xantphos)(Me2bpy)][PF6] exhibits a solid‐state photoluminescence quantum yield of 55% with an excited state lifetime of 17.4 µs. Bright light‐emitting electrochemical cells are obtained using this complex, and it is shown that the electroluminescence quantum yield can be enhanced by using less conducting hole injection layers.
The preparation and characterization of [Cu(POP)(biq)][PF6] and [Cu(xantphos)(biq)][PF6] are reported (biq = 1,1'-biisoquinoline, POP = bis(2-(diphenylphosphanyl)phenyl)ether, and xantphos = (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane). The single crystal structure of [Cu(POP)(biq)][PF6] 0.5Et2O was determined and compared to that in three salts of [Cu(POP)(bq)]+ in which bq = 2,2'-biquinoline. The P–C–P angle is 114.456(19)o in [Cu(POP)(biq)]+ compared to a range of 118.29(3)–119.60(3)o [Cu(POP)(bq)]+. There is a change from an intra-POP PPh2-phenyl/(C6H4)2O-arene π-stacking in [Cu(POP)(biq)]+ to a π-stacking contact between the POP and bq ligands in [Cu(POP)(bq)]+. In solution and at ambient temperatures, the [Cu(POP)(biq)][PF6]+ and [Cu(xantphos)(biq)]+ cations undergo several concurrent dynamic processes, as evidenced in their multinuclear NMR spectra. The photophysical and electrochemical behaviors of the heteroleptic copper (I) complexes were investigated, and the effects of changing from bq to biq are described. Short Cu···O distances within the [Cu(POP)(biq)]+ and [Cu(xantphos)(biq)]+ cations may contribute to their very low photoluminescent quantum yields.
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