Hydrothermal synthesis, thermal behaviour and structure determination from powder data of a porous three-dimensional europium trimesate: Eu-3(H2O)(OH)(6)[C6H3(CO2)(3)]center dot 3H(2)O or MIL-63

A new three-dimensional microporous europium carboxylate has been obtained under hydrothermal conditions using trimesic acid and its structure solved from X-ray powder diffraction data. MIL-63 or Eu-3(H2O)(OH)(6)[C6H3(CO2)(3)].3H(2)O crystallises in monoclinic symmetry with a = 17.640(1), b = 3.689( 2), c = 12.385(1) Angstrom, beta = 91.245(1)degrees, V = 805.74(4) Angstrom(3), space group P2(1) (ndegrees4). Its structure is built up from nine-coordinate monocapped square antiprism europium polyhedra and trimesate anions, creating pillared structures. The inorganic layers of MIL-63 are similar to those of europium hydroxide, but with a periodic oscillation that leaves within the interlayer space two types of pores along the b axis that contain both free and bound water molecules. The thermal behaviour of MIL-63 has been investigated using TGA and X-ray thermodiffractometry, and indicates that MIL-63 is stable up to 723 K and exhibits zeolitic behaviour.