Dimensional selective syntheses of metal-organic frameworks using mixed organic ligands

Abstract

Three metal-organic frameworks (MOFs), Zn(BTX)(m)(L)(n) 1-3 (BTX = 1,4-bis((1H-1,2,4-triazol-1-yl)methyl) benzene; H2L = H(2)IPA (isophthalic acid), H2BDC (terephthalic acid), and H2NDC (naphthalene-2,6-dicarboxylic acid) for 1-3, respectively), were synthesized, and their structures and properties were analyzed. They were prepared by solvothermal reaction of the corresponding mixed ligands with the Zn2+ ion. Single-crystal XRD (SXRD) analysis revealed that 1 and 2 exhibit a 2D layer-stacked structure, whereas 3 shows a 3-fold interpenetrated 3D structure. TGA showed that the structure is thermally stable up to about 350, 317, and 400 degrees C for 1-3, respectively. PXRD showed their structural changes during drying processes. Unlike 1 and 2, only 3 exhibited a sorption isotherm for both N-2 at 77 K and CO2 at 195 K, which showed typical type III and I behaviors, respectively. Thus, the properties of 1-3 are in close connection with dimensionality, which differs depending on their organic ligands.