Syntheses, Structures, and Structural Transformations of Mixed Na(I) and Zn(II) Metal-Organic Frameworks with 1,3,5-Benzenetricarboxylate Ligands

Three new compounds, [ZnNa(BTC)(H2O)(2)]center dot H2O (1), [Zn3Na2(BTC)(2)(HCOO)(2)(H2O)(8)] (2), and [Zn3Na(BTC)(2) (HCOO)(H2O)3]center dot H2O (3) (H3BTC = 1,3,5-benzenetricarboxylate acid), were synthesized under hydrothermal conditions and were characterized by the single crystal and powder X-ray diffraction, IR spectra, elemental analyses, ICP measurements, and coupled TG-MS analyses. 1, 2, and 3 crystallize in the space groups P (1) over bar, C2/c, and P1, respectively. They are three-dimensional (3D) frameworks, consisting of zigzag chains ((Na2Zn2O14)(n) for 1, (Na2Zn3O18)(n) for 2, or (NaZn3O14)(n) for 3) and bridging BTC ligands. Powder X-ray diffraction studies reveal that 1 and 2 exhibit reversible dehydration-rehydration behaviors with a crystal-to-crystal transformation observed for 2.