Synthesis, structure determination and properties of MIL-53as and MIL-53ht: the first Cr-III hybrid inorganic-organic microporous solids: Cr-III(OH)center dot{O2C-C6H4-CO2}center dot{HO2C-C6H4-CO2H}(x)

The first three-dimensional chromium(III) dicarboxylate compounds have been isolated and their structures solved from powder X-ray diffraction data; the flexible framework of these materials delimits large pores.