Synthesis, characterization, and properties of an open-framework iron(III) dicarboxylate:: MIL-85 or FeIII2O{O2C-CH3}2{O2C-C6H4-CO2}•2CH3OH

A new three-dimensional iron(III) dicarboxylate, MIL-85 or (Fe2O)-O-III{O2C-CH3}2{O2C- C6H4-CO2}.2CH(3)OH, has been obtained under solvothermal conditions, and its structure was determined using X-ray powder diffraction data. Its chiral framework is built up from helical chains of iron(III) octahedra linked through terephthalate dianions. This creates a three-dimensional structure with an array of 1-D small-pore channels filled with free and bound methanol moieties. The thermal behavior has been investigated using TGA, and X-ray thermodiffractometry indicates that MIL-85 is stable up to 275 degreesC with a fully reversible departure of solvent process. When the free and bound solvent molecules are removed, a nanoporous solid with a Langmuir surface area of 110 m(2)/g is obtained. Mossbauer spectrometry confirms the presence of high-spin-state Fe3+ within the structure and a change in the iron environment upon solvent departure. Finally, one can conclude from magnetic data that MIL-85 exhibits a frustrated magnetic behavior in the low-temperature range. Crystal data for MIL-85: hexagonal space group P6(1) (no. 169) with alpha = 11.045 (1) Angstrom, c = 18.823 (1) Angstrom, and Z = 6.