title: Synthesis, Structure, and Photophysical Properties of Two Four-Coordinate Cu(I)-NHC Complexes with Efficient Delayed Fluorescence.
abstract: Two luminescent cationic heteroleptic four-coordinate Cu(I) complexes supported by N-heterocyclic carbene ligand and diphosphine ligand were successfully prepared and characterized. These complexes adopt typical distorted tetrahedral configuration and have high stability in solid state. Quantum chemical calculations show carbene units have contributions to both highest occupied molecular orbitals and lowest unoccupied molecular orbitals of these Cu(I)-NHC complexes, the lowest-lying singlet and triplet excitations (S0 → S1 and S0 → T1) of [Cu(Pyim)(POP)](PF6) are dominated by metal-to-ligand charge transfer (MLCT) transition, while the S0 → S1 and S0 → T1 excitations of [Cu(Qbim)(POP)](PF6) are mainly MLCT and ligand-centered transitions, respectively. These Cu(I)-NHC complexes show efficient long-lifetime emissions (λem = 520 nm, τ = 79.8 μs, Φ = 0.56 for [Cu(Pyim)(POP)](PF6), λem = 570 nm, τ = 31.97 μs (78.99%) and 252.2 μs (21.01%), Φ = 0.35 for [Cu(Qbim)(POP)](PF6)) in solid state at room temperature, which are confirmed as delayed fluorescence by investigating the emissions at 77 K.
authors.affiliation: College of Chemistry and Chemical Engineering, Luoyang Normal University , Luoyang, Henan 471022, P. R. China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Caijun
authors.initials: C
authors.lastname: Zheng
authors.affiliation: College of Chemistry and Chemical Engineering, Luoyang Normal University , Luoyang, Henan 471022, P. R. China.
authors.forename: Weizhou
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Chemistry and Chemical Engineering, Luoyang Normal University , Luoyang, Henan 471022, P. R. China.
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.affiliation: College of Chemistry and Chemical Engineering, Luoyang Normal University , Luoyang, Henan 471022, P. R. China.
authors.forename: Baoming
authors.initials: B
authors.lastname: Ji
authors.affiliation: Nano-organic Photoelectronic Laboratory and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.|Functional Nano & Soft Materials Laboratory (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Zhang