Luminescent properties of Ln(III) complexes with 2-[(phenylamino)methylene]-5,5-dimethyl-cyclohexane-1,3-dione as an antenna

Seven lanthanide-based coordination compounds with 2-[(phenylamino)methylene]-5,5-dimethyl-cyclohexane-1,3-dione were synthesized: [Eu(HL)(2)(NO3)(3)] (1), [Sm(HL)(2)(NO3)(3)] (2), [Ce(HL)(2)(NO3)(3)] (3), [Tm(HL)(2)Cl-3]center dot H2O (4), [Tb(HL)(2)Cl-3]center dot H2O (5), [Dy(HL)(2)(H2O)(NO3)(3)] (6) and [Gd(HL)(2)Cl-3]center dot H2O (7). The obtained Eu(III), Sm (III) and Ce(III) nitrate complexes was established to be isostructural just like Tm(III), Tb(III) and Gd(III) chloride ones. Using X-ray diffraction analysis, the structures of cerium and samarium were determined, which occurred to be polymer chains. On the contrary, the dysprosium compound was mononuclear. Ligand was shown to emit in blue region with quantum yield near 12%. For lanthanide complexes of Eu(III), Sm(III), and Tb(III), during the energy transfer from the ligand triplet state to the central atom, characteristic bands of the metal ion are observed in the emission spectra. The lifetimes and quantum yields of luminescence for these complexes were also determined. For other compounds, no energy transfer is observed due to lower energy of ligand triplet state than corresponding emitting state of the lanthanide ions.

Automated summary

Seven lanthanide-based coordination compounds were synthesized with a ligand emitting in the blue region with a quantum yield near 12%. The structures of cerium and samarium were determined to be polymer chains, while the dysprosium compound was found to be mononuclear. Energy transfer from the ligand triplet state to the central atom was observed in Eu(III), Sm(III), and Tb(III) complexes, with characteristic metal ion bands in the emission spectra.