Topological structural diversification of zinc coordination polymers caused by the spacers of different dicarboxylates

As a new generation of multi-functional materials, crystalline coordination polymers have attracted widespread attention due to their fascinating framework structures, interesting topologies and potential applications. Two new coordination polymers, namely, poly[[μ₂-trans-1,2-bis(pyridin-3-yl)ethylene-κ²N:N']bis(μ₃-terephthalato-κ³O:O':O'')dizinc(II)], [Zn₂(C₈H₄O₄)₂(C₁₂H₁₀N₂)]_n or [Zn₂(tp)₂(3,3'-dpe)]_n, (I), and poly[diaqua[μ₂-trans-1,2-bis(pyridin-3-yl)-ethylene-κ²N:N']bis(μ₂-furan-2,5-dicarboxylate-κ²O:O')dizinc(II)], [Zn₂(C₆H₂O₅)₂(C₁₂H₁₀N₂)(H₂O)₂]_n or [Zn₂(fdc)₂(3,3'-dpe)(H₂O)₂]_n, (II), have been prepared by the hydrothermal reactions between Zn(NO₃)₂·6H₂O and trans-1,2-bis(pyridin-3-yl)ethylene (3,3'-dpe) with two similar dicarboxylic acids, i.e. terephthalic acid (H₂tp) and furan-2,5-dicarboxylic acid (H₂fdc), respectively. The coordination framework of (I) is a 3D pcu net with the point symbol 4¹²6³. The void space of the single framework in (I) is filled by the mutual interpenetration of two crystallographically equivalent networks, forming a threefold interpenetrating 3D architecture. Compound (II) is a 2D 3-connected coordination network parallel to the bc plane with the Schläfli symbol 6³. Neighbouring 2D coordination networks are further connected to each other via hydrogen-bonding interactions to produce a 3D supramolecular framework. The thermal stability and photoluminescence properties of these two coordination polymers have also been investigated.