Microporous metal-organic framework constructed from heptanuclear zinc carboxylate secondary building units

A novel, three-dimensional, noninterpenetrating microporous metal-organic framework (MOF), [Zn7O2(pda)(5)(H2O)(2)]center dot 5DMF center dot 4EtOH center dot 6H(2)O (1) (H(2)PDA=p-phenylenediacrylic acid, DMF=NN-dimethylformamide, EtOH=ethanol), was synthesized by constructing heptanuclear zinc carboxylate secondary building units (SBUs) and by using rigid and linear aromatic carboxylate ligands, PDA. The X-ray crystallographic data reveals that the seven zinc centers of 1 are held together with ten carboxylate groups of the PDA ligands and four water molecules to form a heptametallic SBU, Zn7O4(CO2)(10), with dimensions of 9.8 x 9.8 x 13.8 angstrom(3). Furthermore, the heptametallic SBUs are interconnected by PDA acting as linkers, thereby generating an extended network with a three-dimensional, noninterpenetrating, intersecting large-channel system with spacing of about 17.3 angstrom. As a microporous framework, polymer 1 shows adsorption behavior that is favorable towards H2O and CH3OH, and substantial H, uptake. In terms of the heptanuclear zinc carboxylate SBUs, polymer I exhibits interesting photo-electronic properties, which would facilitate the exploration of new types of semiconducting materials, especially among MOFs containing multinuclear metal carboxylate SBUs.