A novel family of 3D photoluminescent lanthanide-bta-flexible MOFs constructed from 1,2,4,5-benzenetetracarboxylic acid and different spanning of dicarboxylate acid ligands

By using 1,2,4,5-benzenetetracarboxylic acid as a rigid polycarboxylate metal linker and three types of flexible dicarboxylate ligands containing different -CH2-spacers as the second linker, a novel family of lanthanide MOFs (1-12) with three kinds of 3D framework structures, namely, [Ln(2)(ox)(bta)(H2O)(4)] (Ln = Eu (1), Tb (2), Dy (3), Ho (4); H(2)ox = oxalic acid; H(4)bta = 1,2,4,5-benzenetetracarboxylic acid), [Ln(2)(glu)(bta)(H2O)(4)]center dot H2O (Ln = Tb (5), Eu (6), Dy (7), Ho (8); H(2)glu = glutaric acid), [Ln(2)(ad)(bta) (H2O)(2)] (Tb (9), Eu (10), Dy (11), Er (12); H(2)ad = adipic acid), have been synthesized under hydrothermal conditions. All coordination polymers were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that the networks of the twelve polymers exhibit a variety of coordination modes to metal centers and all have three dimensional structures. The photoluminescent properties for the polymers 1-3, 5-7 and 9-11 were examined by using luminescence spectra and the analysis results indicate that different spanning flexible linkers have different influence on the characteristic photoluminescence when the rigid linker is the same.