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• Four-coordinate N-heterocyclic carbene (NHC) Cu(I) complexes bearing different diphosphine ligands are synthesized and characterized. • The photophysical properties of the resulting complexes is investigated. • Complexes show yellow-green emission in 525–555 nm region with the phosphorescent origin. • The differences of the photophysical properties were rationalized by DFT and TDDFT calculations. Here, we report a series of the four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes having the same bidenate NHC ligand and different bisphosphine (P^P) ligands, [Cu(CNbenPy-benzIm)(Naphphos)]PF 6 (P1), [Cu(CNbenPy-benzIm)(cyc-xantphos)]PF 6 (P2), and [Cu(CNbenPy-benzIm)(xantphos)]PF 6 (P3), (CNbenPy-benzIm = 3-(3-cyanobenzyl)-1-(5-phenylpyridin-2-yl)-1 H -imidazolylidene; BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene; cyc-xantphos = (9,9-dimethyl-9 H -xanthene-4,5-diyl)bis(dicyclohexylphosphine), xantphos = 9,9-dimethyl-9 H -xanthene-4,5-diyl)bis(diphenylphosphine)). P1 exhibits the metal-to-ligand charge transfer (MLCT) absorption band at 366 nm with high molar extinction coefficient of 2.44 × 104 M−1 cm−1, while P2 and P3 show a blue-shift of the MLCT absorption band at 336–341 nm with the molar extinction coefficients of 0.82–1.16 × 104 M−1 cm−1, which are just a little lower than that of P1. The emission wavelengths of all NHC-Cu(I) complexes can be fine-tuned to cover the spectral range of 525–555 nm with the phosphorescent origin in PMMA films. P1 has the lowest photoluminescence efficiency of 5.50% with the red-shifted emission wavelength at 555 nm and the emission lifetime of 237 μs, whereas P3 show the highest photoluminescence efficiency of 39.5% with the blue-shifted emission wavelength at 525 nm and the emission lifetime of 64.4 μs. The differences for photophysical properties of NHC-Cu(I) complexes were rationalized using density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three-coordinate copper(I) complexes bearing POP and monodentate substituted-quinoline ligands were synthesized and characterized. • The electron-donating/withdrawing groups including methoxyphenyl and trifluoromethylphenyl groups were inserted into the complexes. • Cu(I) complexes exhibited yellow-green emissions at 542-558 nm with longer excited-state lifetimes of 179–487 µs. • The photophysical properties were explained by DFT and TDDFT calculations. The three-coordinate Cu(I) complexes [Cu(POP)(X)]PF 6 , X = quinoline (P1), 2-(4-methoxyphenyl)quinoline (P2), 2-(4-(trifluoromethyl)phenyl)quinoline (P3), POP = bis[(2-diphenylphosphino)phenyl] ether were synthesized and characterized. The photophysical properties of these Cu(I) complexes were tuned by the addition of organic groups including methoxyphenyl and trifluoromethylphenyl groups into the quinoline ligand. The resulting complexes exhibit the metal-to-ligand charge transfer (MLCT) band in the lower energy. The emissions for all the complexes in solid state are in the range of 542–558 nm with higher quantum yields of 11.4–14.2% and long-lived excited lifetimes of 179–481 µs at room temperature. The photophysical properties were further explained by DFT and TDDFT methods. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of copper(I) complexes bearing benzothiazole-imidazolylidene-type N -heterocyclic carbene (NHC) ligands are reported. All the complexes emit bright yellow-green light (λ em = 543–551 nm) with higher emission quantum yields of 24.9–44.1% and excited state lifetimes on the microsecond scale (t = 13.7–32.7 μs) in PMMA films. [Display omitted] The synthesis and photophysical investigation of a series of copper(I) complexes bearing benzothiazole-imidazolylidene-type N -heterocyclic carbene (NHC) ligands are reported. Their photophysical properties are tuned by adjusting the different substituens at 6-position of the benzothiazole ring. C1 and C2 exhibit the lowest-lying metal-to-ligand charge transfer (MLCT) absorption bands at 325–400 nm, while the MLCT band of C3 is almost unresolved owing to the blue shift of this band. Upon excitation with UV light all the complexes emit bright yellow-green light (λ em = 543–551 nm) with higher emission quantum yields of 24.9–44.1% and excited state lifetimes on the microsecond scale (τ = 13.7–32.7 μs) in PMMA films. Additionally, the electronic properties, absorption and emission profiles of these complexes were further explored using DFT/TDDFT methods. [ABSTRACT FROM AUTHOR]

• Schiff base-type copper(I) complexes were synthesized and characterized. • Triphenylamine group was employed to construct copper(I) complexes with high light absorption abilities. • The photophysical properties of complexes including phenyl, naphthyl and adamantanyl groups were investigated.. • DFT/TDDFT methods were employed to rationalize the photophysical properties. The three Schiff base-type Cu(I) complexes [Cu(POP)(N^N)]PF 6 , N^ N = N ,N-diphenyl-4-(6-((phenylimino)methyl)pyridin-3-yl)aniline (P1), N-((5-(4-(diphenylamino)phenyl)pyridin-2-yl)methylene)naphthalen-2-amine (P2), N-((5-(4-(diphenylamino)phenyl)pyridin-2-yl)methylene)adamantan-1-amine (P3), were prepared and characterized. The photophysical properties of these Cu(I) complexes is tuned by the addition of different substituents such as phenyl, naphthyl and adamantanyl groups into the backbone of Schiff base ligand. The resulting complexes exhibit high absorption ability in the visible region with molar extinction coefficients of up to 3 7400 M−1 cm−1. The emissions in CH 2 Cl 2 solution are in the range of 551–552 nm with lower quantum yields of 1.1–2.0% and short-lived excited lifetimes of 2.78–3.09 ns for all the complexes at room temperature. The photophysical properties were further explained by DFT and TDDFT methods. [Display omitted] [ABSTRACT FROM AUTHOR]