Synthesis, structures, and photophysical properties of orange-red emissive Cu(I) complexes of 9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-xanthene (Xantphos) with the substituted N-hetercycle carbene (NHC) ligand

In the present study, a series of the four-coordinate N-hetercycle carbene (NHC) copper (I) complexes [Cu(Ph-Im-cyPy)(Xantphos)]PF6 (P1), [Cu(DimBenPh-Im-cyPy)(Xantphos)]PF6 (P2), and [Cu(BenDimBenIm-CNPy)(Xantphos)]PF6 (P3), Ph-Im-cyPy=3-benzyl-1-(4-cyano-pyridin-2-yl)-1H-imidazolylidene, DimBenPh-Im-cyPy=3-(3,5-dimethylbenzyl-1-(4-cyano-pyridin-2-yl)-1H-imidazolylidene, BenDimBenIm-CNPy=3-benzyl-1-(4-cyano-pyridin-2-yl)-1H-5,6-dimethylbenzimidazolylidene, Xantphos=9,9-dimethyl-4,5-bis(diphenylphosphino)-9H-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.