3D Racemic Microporous Frameworks and 3D Chiral Supramolecular Architectures Based on Evans-Showell-Type Polyoxometalates Controlled by the Temperature

Four new architectures containing [Co2Mo10H4O38](6-) polyoxoanion, [Ln(H2O)(7)][Ln(H2O)(5)][Co2Mo10H4O38]center dot 5H(2)O (Ln = Gd 1; Tb 2), and (NH4)(3)[Ln(H2O)(6)][Co2Mo10H4O38]center dot 6H(2)O (Ln = Gd 3; Tb 4) have been synthesized at different temperatures and characterized by elemental analysis, IR and Raman spectroscopy, TG analysis, powder X-ray diffraction and single crystal X-ray diffraction. Isostructural compounds 1 and 2 obtained at the higher temperature (85 degrees C), are built up of Evans-Showell-type polyoxoanions [Co2Mo10H4O38](6-), respectively, linked by Gd3+ or Tb3+ cations to form a 3D racemic framework with 1D zigzag channels. From the topological point of view, the 3D net is a rare binodal 4-connected SrAl2 (sra) topology. As far as we know, compounds 1 and 2 represent the first examples of 3D architectures based on Evans-Showell-type polyoxometalate. Interestingly, the stable 3D microporous compounds exhibit selective adsorption ability: adsorbing water and methanol, as well as excellent photocatalytic activity for organic dye degradation under visible light irradiation. When the reaction temperature was decreased to room temperature (25 degrees C), two chiral species 3 and 4 were obtained, with a monosupporting structure composed of one [Co2Mo10H4O38](6-) polyoxoanion and one [Ln(H2O)(6)](3+) unit. These chiral monosupporting motifs can be connected by strong hydrogen-bonding interactions to form a 3D chiral supramolecular architecture. They crystallize in the chiral space group P2(1), as conglomerates of two enantiomerically pure crystals. Their absolute configurations were determined by the Flack parameters and solid-state circular dichroism spectroscopy.