Hydrogen bonded-extended lanthanide coordination polymers decorated with 2,3-thiophenedicarboxylate and oxalate: synthesis, structures, and properties

Abstract

Five new lanthanide coordination polymers, {[Ln₂(tdc)₂(C₂O₄)(H₂O)₄]·(H₂O)}_n (Ln = Nd (1), Eu (2), Gd (3), Tb (4), Ho (5); H₂tdc = 2,3-thiophenedicarboxylic acid), have been synthesized by hydrothermal reactions of H₂tdc, sodium oxalate and the corresponding lanthanide nitrate. Crystallographic data show that 1–5 are isomorphous and crystallize in the monoclinic space group C2/c. Each complex contains an oxalate-linked two-dimensional (2D) sql layer structure based on dinuclear [Ln₂(tdc)₂(H₂O)₄] building units. Then the 2D layers are further extended by intermolecule hydrogen bonds to form a three-dimensional (3D) supramolecular network with sxb topology. Compounds 2 and 4 display luminescence emission in the visible region, while compounds 1 and 5 exhibit luminescence emission in the near IR region. Dehydrated 1 as a Lewis acid catalyst exhibits high catalytic activity and stability in acetalization reaction under mild conditions. Furthermore, infrared, thermogravimetric analysis, elemental analyses, and powder X-ray diffraction properties of these compounds are also studied.