Synthesis, Structure and Properties of Lanthanide-Organic Frameworks with Imidazolylmethylisophthalate Ligands

Three new lanthanide-organic frameworks {[Ln(L)(OClO₃)(H₂O)]·0.5H₂O}_n [Ln = Sm (1), Eu (2), Er (3)] have been prepared by hydrothermal reactions of the corresponding lanthanide oxide (Ln₂O₃), silver perchlorate (AgClO₄) and 5-(imidazol-1-ylmethyl)isophthalic acid. The complexes have been characterized by single-crystal and powder X-ray diffraction, IR spectroscopy, and elemental analyses. In 1–3, the metal centers are eight-coordinated to show polyhedral coordination geometries with an LnO₈ donor set. The imidazolyl groups are free of coordination, and the perchlorate and carboxylate groups bridge the Ln³⁺ cations leading to the formation of wave-like layer structures containing metal-chains. The fluorescence properties of complex 2 were investigated.