title: Accesses to electronic structures and the excited states of blue luminescent copper(I) complexes containing N-heterocyclic carbene ligands: a DFT/TDDFT exploitation.
abstract: The ground electronic states and photophysical properties of three designed Cu(I) complexes [Cu(ImNHC)(POP)](+) (1), [Cu(methyl-ImNHC)(POP)](+) (2), and [Cu(BenzImNHC)(POP)](+) (3); where [ImNHC = 3-methyl-1-(pyridin-2-yl)-1H-imidazol-2-ylidene; methyl-ImNHC = 3-methyl-1-(pyridin-2-ylmethyl)-1H-imidazol-2-ylidene; BenzImNHC = 3-methyl-1-(pyridin-2-yl)-1H-benzimidazol-2-ylidene], have been investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The results reveal that the presence of the methylene spacer in the NHC ligands has a more direct effect on the distribution of frontier molecular orbitals while the elongation of π conjugation provided by the fused imidazole in the NHC ligands has a negligible effect. The UV-vis absorption spectra of all the complexes are well produced by TD-DFT calculations based on the charge transfer amount calculations and the corresponding band assignments are discussed. Importantly, the triplet energy calculations demonstrated that complex 2 would be a highly efficient blue emitter with the deep-blue of 440 nm.
authors.affiliation: Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Fenglin Street, Nanchang, Jiangxi, 330013, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.forename: Shengxian
authors.initials: S
authors.lastname: Xu
authors.forename: Hongying
authors.initials: H
authors.lastname: Xia
authors.forename: Jinglan
authors.initials: J
authors.lastname: Wang
authors.forename: Yibo
authors.initials: Y
authors.lastname: Wang
mesh_terms: D003116:Color; D003198:Computer Simulation; D003300:Copper / Q000737:chemistry*; D004583:Electrons; D004735:Energy Transfer; D008024:Ligands; D049449:Luminescence; D049408:Luminescent Agents / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D008024:Ligands; D049408:Luminescent Agents; C030011:carbene; D003300:Copper; D008697:Methane