Synthesis, characterization and sorption properties of zinc(II) metal-organic framework containing methanetetrabenzoate ligand

Porous metal-organic framework {[Zn-2(MTB)(H2O)(2)]center dot 3H(2)O center dot 3DMF}(n) (where MTB = methanetetrabenzoate, DMF = N,N'-dimethylformamide) was prepared by solvothermal route and characterized by elemental analysis, FT-IR spectroscopy, thermal analysis coupled with mass spectrometry, single-crystal X-ray diffraction and adsorption of nitrogen and carbon dioxide. Structure of the compound is formed by the clusters of paddle-wheel secondary building units (SBUs) with composition [Zn-2(H2O)(2)(COO)(4)] (COO = carboxylate group), which are interconnected through tetraphenylmethane core of MTB4- ligand with tetrahedral spatial arrangement. This interconnection gives rise to the final 3D porous structure of the compound with the channels propagating along a, b and c crystallographic axes. The sizes of the channel openings, after substraction of van der Waals radii of the atoms, were 21.2 x 6.0, 9.0 x 9.0 and 6.0 x 6.0 angstrom(2). The accessibility of the pores for the guest molecules was revealed by the measurements of adsorption of nitrogen and carbon dioxide. The specific surface area determined from nitrogen adsorption at 77 K using BET equation was 248 m(2) g(-1), and the pore volume calculated using t-plot was 0.0891 cm(3) g(-1). Sorption of carbon dioxide was performed at two temperatures 273 and 293 K giving the sorption capacities 5.67 and 4.74 wt.%, respectively. (C) 2012 Elsevier B.V. All rights reserved.