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[Display omitted] • Dinuclear N-heterocyclic carbene (NHC) Cu(I) complexes bearing the mixed bis-NHC and POP ligands are synthesized and characterized. • Complexes show intense yellow-green emission in 531–571 nm region originated from the delayed fluorescence. • The photophysical properties were rationalized by DFT and TDDFT calculations. • Green and yellow light-emitting diodes and anti-counterfeiting applications were fabricated successfully. Here, a series of dinuclear N-heterocyclic carbene (NHC) copper(I) complexes having 3,3′-(1,4-phenylenebis(methylene))bis(1-(pyridin-2-yl)-1H-imidazolylidene as bis-NHC ligand and bis[(2-diphenylphosphino)phenyl]ether (POP) as auxiliary ligand have been successfully prepared, and their photophysical properites were investigaged experimentally and theocitcally. The resulting complexes all exhibited intense green to yellow emission that originated from the thermally activated delayed fluorescence (TADF) with a high photoluminescence quantum yield of up to 0.67 and longer excited-state lifetimes on the microsecond time scale in the solid state. Green and yellow light-emitting diode (LED) devices based on Cu(I) complexes have successfully achieved good color rendering indices. Moreover, the anti-counterfeiting patterns and QR codes made of Cu(I) complexes have been applied to clothing, banknotes, books and glass plates with excellent anti-counterfeiting effects. [ABSTRACT FROM AUTHOR]

• Four-coordinate N -heterocyclic carbene (NHC) Cu(I) complexes having the pyridyl-imidazolylidene ligand are synthesized and characterized. • The photophysical properties of the resulting complexes is investigated. • Complexes show yellow-green emission in 543–555 nm region with the higher photoluminescence efficiency. • DFT and TDDFT calculations are taken to support the differences of the photophysical properties. The synthesis, characterization and photophysical properties of a series of the four-coordinate N -heterocyclic carbene (NHC) copper(I) complexes are reported. These NHC-Cu(I) complexes contain two bidentate ligands, the R -substituted pyridyl-imidazolylidene-type ligand and diphosphine ligand bis [(2-diphenylphosphino)phenyl] ether (POP). The photophysical properties of these complexes can be adjusted depending on the nature of substituents at 4-position of the phenyl ring in the NHC ligand. The metal-to-ligand charge transfer (MLCT) absorption band can be observed for all complexes at 348–362 nm, and the emission wavelengths can be fine-tuned to cover the spectral range of 543–555 nm with the higher photoluminescence efficiency of up to 66.2% in the solid state. Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were employed to support potophysical properties of the NHC-Cu(I) complexes. [Display omitted] [ABSTRACT FROM AUTHOR]

• 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 four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes, [Cu(Ph-BenIm-Py)(POP)]PF 6 ( 1 ), [Cu(Naph-BenIm-Py)(POP)]PF 6 ( 2 ), and [Cu(Anthr-BenIm-Py)(POP)]PF 6 ( 3 ) (Ph-BenIm-Py = 3-benzyl-1-(pyridin-2-yl)-1 H -benzimidazolylidene, Naph-BenIm-Py = 3-(naphthalen-2-yl-1-(pyridin-2-yl)-1 H - benzimidazolylidene, Anthr-BenIm-Py = 3-(anthracen-9-yl)-1-(pyridin-2-yl)-1 H -benzimidazolylidene, and POP = bis[2-diphenylphosphino]-phenyl)ether) have been synthesized and characterized. The different aryl substituents (phenyl, naphthyl, and anthracyl groups) were introduced into NHC ligands and the corresponding photophysical properties of the complexes were systematically investigated. The absorption spectra of all NHC Cu(I) complexes show a characteristic feature of metal-to-ligand charge transfer (MLCT) in the lower-energy region. Complex 1 exhibited good photoluminescence (PL) properties companying with the high quantum yields and long excited-state lifetimes, whereas 2 and 3 with naphthyl and anthracyl groups show the low PL efficiency caused by the strong π-π stacking interactions. Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were employed to rationalize the photophysical properties of the NHC Cu(I) complexes. [ABSTRACT FROM AUTHOR]

Three four-coordinated N-heterocyclic carbene (NHC) copper(I) complexes, [Cu(NaphIm-Py)(POP)]PF 6 ( 1 ), [Cu(AnthrIm-Py)(POP)]PF 6 ( 2 ), and [Cu(PhBenIm- c -Py)(POP)]PF 6 ( 3 ) (NaphIm-Py = 3-(naphthalen-2-ylmethyl-1-(pyridin-2-yl)-1 H -imidazolylidene, AnthrIm-Py = 3-(anthracen-9-ylmethyl)-1-(pyridin-2-yl)-1 H -imidazolylidene, PhBenIm- c -Py = 3-benzyl-1-(pyridin-2-ylmethyl)-1 H -benzo[ d ]imidazolylidene, POP = bis[2-diphenylphosphino]-phenyl)ether) have been synthesized and characterized. The effect of varying carbene ligands with different substituents on the structural aspects and photophysical properties of the complexes is systematically investigated. The lowest absorption bands of 1 at about 350 nm are assigned as metal-to-ligand charge transfer (MLCT) character with some contribution from ligand-to-ligand charge transfer (LLCT) character, while the π-π* transition of the anthryl group are responsible for the lowest absorption band of 2 . For 3 , no MLCT absorption band are observed in lower energy region. The emission wavelengths of all NHC-Cu(I) complexes are in the range of 520–550 nm with the phosphorescent origin in the solid state. 1 and 2 with naphthyl and anthryl groups show the lower photoluminescence efficiency due to the strong π-π stacking interactions, whereas 3 exhibit good photoluminescence properties companying with the higher quantum yields and long excited-state lifetimes. Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were employed to rationalize the photophysical properties of the NHC-Cu(I) complexes. [ABSTRACT FROM AUTHOR]

Three four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes, [Cu(Py-Im)(POP)](PF6) (P1), [Cu(Py-BenIm)(POP)](PF6) (P2), and [Cu(Py-c-BenIm)(POP)](PF6) (P3) (Py-Im = 3-methyl-1-(pyridin-2-yl)-1H-imidazolylidene, Py-BenIm = 3-methyl-1-(pyridin-2-yl)-1H-benzo[d]imidazolylidene, Py-c-BenIm = 3-methyl-1-(pyridin-2-ylmethyl)-1H-benzo[d]imidazolylidene, POP = bis([2-diphenylphosphino]-phenyl)ether), have been synthesized without transmetalation of the NHC–Ag(I) complex for the first time. The photophysical properties of the resultant NHC–Cu(I) complexes have been systematically investigated via spectroscopic methods. All complexes exhibit good photoluminescence properties with long excited-state lifetimes and moderate quantum yields. Density functional theory and time dependent density functional theory calculations were employed to rationalize the photophysical properties of the NHC–Cu(I) complexes. [ABSTRACT FROM AUTHOR]

• Four-coordinate N-heterocyclic carbene (NHC) Cu(I) complexes with thiazole/benzoxazole moiety are synthesized and characterized. • The photophysical properties of the resulting complexes is investigated. • Complexes show blue-green emission in 517–551 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 with imidazolylidene and POP ligands, [Cu(BenzThiazolyl-Im)(POP)]PF 6 (P1), [Cu(BenzThiazolyl-BenIm)(POP)]PF 6 (P2), [Cu(BenzBenzoxazolyl-Im)(POP)]PF 6 (P3), and [Cu(BenzBenzoxazolyl-BenIm)(POP)]PF 6 (P4), (BenzThiazolyl-Im=3-benzyl-1-(thiazol-2-yl)-1 H -imidazolylidene, BenzThiazolyl-BenIm=3-benzyl-1-(thiazol-2-yl)-1 H -Benzoimidazolylidene BenzBenzoxazolyl-Im=3-benzyl-1-(benzoxazol-2-yl)-1 H -imidazolylidene, BenzBenzoxazolyl-BenIm=3-benzyl-1-(benzocazol-2-yl)-1 H -imidazolylidene, POP=bis[2-diphenylphosphino]-phenyl)ether). Thiazole/benzoxazole moiety were functionalized onto imidazolylidene ligand to tune the photophysical properties of the corresponding complexes. P1 and P2 exhibit the metal-to-ligand charge transfer (MLCT) absorption band with the onset at 406–412 nm, while P3 and P4 have similar MLCT band with the onset at 380–389 nm. The emission wavelengths of all NHC Cu(I) complexes can be fine-tuned to cover the spectral range of 517–551 nm with the phosphorescent origin in PMMA films. P2 show the highest photoluminescence efficiency of 40.9% with the red-shifted emission wavelength at 551 nm, whereas P4 has the lowest photoluminescence efficiency of 1.80% with the blue-shifted emission wavelength at 517 nm. Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were employed to rationalize the differences for photophysical properties of the NHC Cu(I) complexes. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present study, a series of the four-coordinate N-hetercycle carbene (NHC) copper (I) complexes [Cu(Ph-Im-cyPy)(Xantphos)]PF 6 (P1), [Cu(DimBenPh-Im-cyPy)(Xantphos)]PF 6 (P2), and [Cu(BenDimBenIm-CNPy)(Xantphos)]PF 6 (P3), Ph-Im-cyPy=3-benzyl-1-(4-cyano-pyridin-2-yl)-1 H -imidazolylidene, DimBenPh-Im-cyPy=3-(3,5-dimethylbenzyl-1-(4-cyano-pyridin-2-yl)-1 H -imidazolylidene, BenDimBenIm-CNPy=3-benzyl-1-(4-cyano-pyridin-2-yl)-1 H -5,6-dimethylbenzimidazolylidene, Xantphos=9,9-dimethyl-4,5-bis(diphenylphosphino)-9 H -xanthene, have been synthesized and characterized. The molecular structures of P1 – P3 have been established by single-crystal X-ray diffraction study. In the solid state, P1 – P3 exhibit orange-red emission in the range of 621–643 nm with shorter excited-state lifetimes (τ) of 5.73–6.42 μs and the emission quantum yields (Φ) of 1.0–3.9 % at room temperature. Additionally, the photophysical properties are explained by using density functional theory (DFT) and time dependent DFT. [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]

A series of six N -heterocyclic carbene (NHC) copper(I) complexes bearing benzimidazolylidene-type carbene ligands with different substituents are reported. All complexes emit bright yellow-green light (λ em = 540–573 nm) with higher photoluminescence quantum yields (PLQY) of 21.1–55.6 % and excited state lifetimes on the microsecond scale (τ = 30.6–62.1 μs) in PMMA films. [Display omitted] The synthesis and photophysical investigation of a series of six copper(I) complexes bearing benzimidazolylidene–type N–heterocyclic carbene (NHC) ligands with different groups are reported. Their photophysical properties can be tuned by adjusting the groups at the R 1 /R 2 positions of the pyridine ring. The lowest-lying metal–to–ligand (MLCT) absorption bands at 325–437 nm can be observed for all the complexes. Upon excitation with UV light all the complexes emit bright yellow-green light (λ em = 540–573 nm) with higher emission quantum yields of 21.1–55.6% and excited state lifetimes on the microsecond scale (τ = 30.6–62.1 μs) in PMMA films. The substituents (R 2 = COCH 3 , F, Br, CH 3 , or OCH 3) on R 2 –position of the pyridine ring were shown to have effects on the emission wavelengths of these complexes, while the introduction of R 1 substituents (R 1 = CH 3) shows negligible effects on the emission wavelength but allow the enhancement of photoluminescence quantum yield (Φ) of the complexes. Additionally, the electronic properties, absorption and emission profiles of these complexes were further explored using DFT/TDDFT methods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four-coordinate N-heterocyclic carbene (NHC) Cu(I) complexes with various substituents are synthesized and characterized. • The photophysical properties of the corresponding complexes is studied. • Complexes exbihit bright photoluminescence with orange-red color. • DFT and TDDFT calculations were employed to rationalize the photophysical properties. Herein, three four-coordinate N-hetercycle carbene (NHC) copper (I) complexes of the types [Cu(BenDimBenIm-CHOPy)(POP)]PF 6 (P1), [Cu(BenDimBenIm-CNPy)(POP)]PF 6 (P2), and [Cu(DimbenDimBenIm-CNPy)(POP)]PF 6 (P3) (BenDimBenIm-CHOPy = 3-benzyl-1-(5-formyl -pyridin-2-yl)-1 H -5,6-dimethylbenzimidazolylidene, BenDimBenIm-CNPy = 3-benzyl-1-(5-cyano -pyridin-2-yl)-1 H -5,6-dimethylbenzimidazolylidene, DimbenDimBenIm-CNPy = 3-(3,5-dimethylbenzyl-1-(5-cyano-pyridin-2-yl)-1 H -5,6-dimethylbenzimidazolylidene, POP = bis[2-diphenylphosphino]-phenyl)ether) have been prepared and investigated. All complexes exhibit the lowest energy metal-to-ligand charge transfer (MLCT) characters in 320–360 nm region showing a slight blue-shift of the absorption maxima in the order P1 > P2 > P3. The emissive wavelength can be fine-tuned to cover the orange-red spectral range of 615−638 nm with higher photoluminescence quantum yields (PLQY) of 17.6–40.3 %. Additionally, the photophysical properties are also investigated theoretically using density functional theory (DFT) and time dependent DFT. [ABSTRACT FROM AUTHOR]