Structural characterization, DFT studied, luminescent properties of cationic/neutral three‐coordinated copper (I) complexes and application in warm‐white light‐emitting diode

A series of cationic/neutral copper (I) complexes, [Cu 2 (Hbmb)(PPh 3 ) 4 ] (BF 4 ) 2 ( 1a ), [Cu 2 (Hbmb)(DPEPhos) 2 ](BF 4 ) 2 ( 2a ), [Cu 2 (Hbmb)(Xantphos) 2 ](BF 4 ) 2 ( 3a ), [Cu 2 (bmb)(PPh 3 ) 4 ] ( 1b ), [Cu 2 (bmb)(DPEPhos) 2 ] ( 2b ), [Cu 2 (bmb)(Xantphos) 2 ] ( 3b ) (Hbmb = 1,4‐bis (1H‐benzimidazol −2‐yl)benzene, PPh 3 = triphenylphosphine, DPEPhos = bis[2‐(diphenylphosphino)‐phenyl]ether, Xantphos =4,5‐bis (diphenylphosphino)‐9,9′‐dimethyl‐xanthene), have been synthesized and characterized by IR, TGA, XRD and X‐ray crystal structure analysis. The structural analysis reveals that each Cu + in all complexes adopts an almost ideal trigonal planar geometry, with three coordinate NP 2 , and the C‐H···π and π···π interactions are observed in the packing structures. DFT studied indicate the ingredients of the HOMOs and LUMOs for neutral copper (I) complexes 1b , 2b and 3b are different from cationic copper (I) complexes 1a , 2a and 3a , in accordance with the distribution of Mülliken atomic charges. Meanwhile, neutral copper (I) complexes 1b , 2b and 3b have fascinating broad blue‐green emission bands at room temperature, while cationic copper (I) complexes 1a , 2a and 3a exhibit the existence of multiple emission peaks. Furthermore, the maximum phosphorescent lifetime and quantum yield at room temperature, for all copper (I) complexes, are 1143 μs and 8.82%, respectively. In addition, in order to measure the practical application of these complexes, the selection of complex 1b is used to fabricate the LED, which emits a bright warm‐white light.