ZrIV Coordination Polymers Based on a Naturally Occurring Phenolic Derivative

The reactivity under solvothermal conditions of the Zr-IV ion with the naturally occurring gallic acid ligand has been evaluated in depth. The study led to the isolation of four microcrystalline hydroxycarboxylate-based coordination polymers (MIL-151 to -154). Through the use of a combination of solid-state NMR and high-resolution X-ray powder diffraction analyses, the structures of two of these phases (MIL-153, MIL-154) were solved. In both cases, the gallol motifs favour the formation of rod-like inorganic units built up from ZrO8 polyhedra. Although one compound (MIL-151) was found to be microporous (S-BET approximate to 470 m(2)g(-1)), its poor crystallinity prevented comprehensive structural analysis. Nevertheless, a comparison of its physicochemical features with those of the fully characterized solids allows a plausible structural model to be proposed.