刚性配体构筑的二维稀土配位聚合物对铜离子和2,4,6-三硝基苯酚的识别作用研究

new series of five lanthanide(III) metal-organic frameworks with a general formula of [Ln3(bcpb)4(μ-HCOO)(μ-H2O)(H2O)2(DEF)]n (1-5) was generated by solvothermal reactions from Ln(NO3)3 6H2O {Ln = Eu (1), Tb (2), Gd (3), Dy (4), and Sm (5)} and 3,5-bis(3-carboxyphenyl)pyridine (H2bcpb) in an aqueous N,N-diethylformamide (DEF) medium. The obtained products were characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis (TGA), powder and single crystal X-ray diffraction. The latter reveals that all compounds 1-5 are isostructural and feature very intricate 2D metal-organic frameworks. These were topologically analyzed, revealing a very complex hexanodal underlying net that can be simplified further to a binodal 3,5-connected layer with the 3,5L52 topology. Solid-state photoluminescent properties of 1-5 were studied in detail. Compound 1 exhibits a strong red luminescence upon excitation at 338 nm and its lifetime is 532 μs. Compound 2 shows an intense green luminescence upon excitation at 336 and its lifetime is 981 μs. The triplet state (3ππ*) of bcpb2- studied by the Gd(III) derivative 3 demonstrated that the ligand effectively populates Tb(III) emission (Φ = 70.96%), whereas the corresponding Eu(III) derivative 1 shows a weak luminescence efficiency (Φ = 15.81%) as the triplet state of bcpb2- has a poor match with the 5D1 energy level of Eu(III). A notable feature of 1 concerns its remarkable sensing ability for Cu2+ ions and 2,4,6-trinitrophenol (TNP).