Polymeric REE coordination compounds based on novel enaminone derivative

• Published in: Polyhedron 2022-11, Vol.227, p.116122, Article 116122
• Main Authors: Smirnova, K.S., Ivanova, E.A., Eltsov, I.V., Pozdnyakov, I.P., Russkikh, A.A., Dotsenko, V.V., Lider, E.V.
• Format: Article
• Language: English
• Subjects: DFT-calculations; Enaminone; Lanthanide(III) complexes; Photoluminescence; Polymeric structure
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2022.116122

New enaminone derivative and five REE coordination compounds based on it were synthesized and characterized some physico-chemical methods. In accordance with DFT-calculations, the electron density of HOMO/LUMO is centered on cyclohexanedione/enaminone as well as methoxybenzene moieties. The bidentate-bridging coordination of ligand results in net polymeric structure, and polyhedron of central atom is close to sphenocorona. Photoluminescence of free ligand in polycrystalline state is dramatically quenched by the presence of methoxy substituent. Energy transfer from the ligand to lanthanide ions is observed only for europium(III) and, in less extent, samarium(III) complexes. [Display omitted] A novel enaminone derivative, 2-{[(3-methoxyphenyl)amino]methylene}-5,5-dimethylcyclohexane-1,3-dione (HL) and its lanthanide(III) complexes [Ln(HL)2(NO3)3]n have been prepared. The composition and structure of products have been investigated using IR-spectroscopy, elemental and X-ray diffraction analysis (powder and single-crystal). HOMO/LUMO, as well as triplet state energy has been established by means of DFT calculations. According to the single-crystal X-ray diffraction analysis, the enaminone ligand exhibits bidentate-bridging coordination resulting in polymeric net. All obtained complexes are isomorphous to each other. Photoluminescence of free ligand in polycrystalline state is very low; the quantum yield is only 0.33%, most probably due enhancement of internal conversion in the singlet excited state by the presence of methoxy substituent. Energy transfer from the ligand to lanthanide ions is observed only for europium(III) and, in less extent, samarium(III) complexes.