Syntheses, structure, and properties of a series of three-dimensional lanthanide-based hybrid frameworks

A novel family of lanthanide hybrid frameworks, {[Ln2(IDA)3]·(H2O)2}n (Ln = Nd (1), Eu (2), Tb (3), Dy(4); H2IDA = iminodiacetic acid), has been synthesized from the self-assembly of the lanthanide ions (Ln3+) with iminodiacetic acid under hydrothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Structural analyses revealed 1–4 have intricate frameworks with three-dimensional (3D) Ln–O–Ln inorganic connectivity, in which the IDA2- − ligands adopt the different μ(3- and μ(4- bridging forms. The 3D inorganic skeleton of the hybrid can be described as helices of corner-sharing LnN1O8 polyhedra connected by edge-sharing dinuclear Ln2N4O12 units, specified by the Schlafli symbol of 8·.8·.103 as a 82·.10-a (lig) topology. The structures also show intersected lanthanide oxide ring channels occupied by guest water molecules, based on which the reversible de-/rehydration occurs. Photoluminescence measurements indicate 2 and 3 are red and green emitters, respectively, in the solid state at room temperature. Besides, the magnetic properties of 1 have been studied.