Three-dimensional lanthanide thiophenedicarboxylate framework with an unprecedented (4,5)-connected topology

Three novel three-dimensional metal-organic frameworks [Ln(2)(tdc)(3)(H2O)(4)](n), Ln = Dy(1), Ho(2), Er(3) (H(2)tdc = thiophene-2,5-dicarboxylic acid) have been synthesized and characterized by single crystal X-ray diffraction (XRD), powder XRD and IR spectra. X-ray crystallography reveals that the three complexes are isostructural and exhibit an unprecedented (4,5)-connected (4(2)center dot 6(4))(4(2)center dot 6(7)center dot 8) topology, in which the lanthanide ions act as unusual 5-connected nodes. The thermal stability and UV-vis absorption spectra of the title complexes have also been studied.