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

Abstract

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, [Ln₂(ox)(bta)(H₂O)₄](Ln = Eu (1), Tb (2), Dy (3), Ho (4); H₂ox = oxalic acid; H₄bta = 1,2,4,5-benzenetetracarboxylic acid), [Ln₂(glu)(bta)(H₂O)₄]·H₂O (Ln = Tb (5), Eu (6), Dy (7), Ho (8); H₂glu = glutaric acid), [Ln₂(ad)(bta)(H₂O)₂] (Tb (9), Eu (10), Dy (11), Er (12); H₂ad = 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.