Molecular Rectangles with Rod‐Shaped Disulfonic Acids

Polysulfonic acids and their compounds have been scarcely investigated, despite the huge knowledge that we have of the respective polycarboxylic acids and polycarboxylates. This is because of the limited availability of polysulfonic acids, for which reliable synthetic protocols are often lacking. Here, we present the first compound of the recently reported disulfonic acid 1,4-bis(4-sulfophenyl)butadiyne (H2DPBDS) prepared in our groups and a new compound of the commercially available 4,4′-biphenyldisulfonic acid (H2BPDS). The zinc sulfonates [Zn2(BPDS)2(NMP)6]·2NMP [I, NMP = N-methylpyrrolidone; triclinic, P, Z = 2, a = 972.8(2), b = 981.5(2), c = 1915.2(2) pm, α = 87.73(3)°, β = 77.68(3)°, γ = 89.36(3)°, V = 1785.0(6) A3] and [Zn2(DPBDS)2(DMA)6]·2DMA [II, DMA = dimethylacetamide; triclinic, P, Z = 2, a = 973.79(2), b = 1347.53(2), c = 1411.08(2) pm, α = 110.531(1)°, β = 92.445(1)°, γ = 101.931(1)° V = 1683.11(5) A3] display rigid molecular rectangles constructed from two zinc atoms and two sulfonate ligands. The rectangles are assembled through weak interactions to form soft host lattices that incorporate the solvent DMA or NMP molecules, partly through Zn2+ coordination. Thermal analysis shows that the solvent molecules can be completely removed without decomposition of the coordination polymers.