Hydrothermal synthesis and crystal structures of two open-framework fluorinated aluminum phosphates templated by 1,3-diaminopropane (ULM-4 & MIL-64)

Two fluorinated aluminophosphates called ULM-4 (Al6(PO4)6F4⋅2H3N(CH2)3NH3⋅H2O) and MIL-64 (Al10(PO4)4(HPO4)6F9(H2O)4⋅ OH⋅4N2C3H12) have been prepared in the presence of HF and 1,3-diaminopropane as a structure-directing agent under hydrothermal conditions (autogeneous pressure, 180 °C, 8–48 hours and 1 months, respectively). ULM-4 crystallises from a F/Al ratio of 1 whereas MIL-64 is obtained with F/Al = 2. The structures have been determined using room temperature single crystal X-ray diffraction data. ULM-4 is described in the noncentric monoclinic space group P21 (n° 4) with the unit cell parameters: a=8.5552(2) Åa=8.5552(2) Å, b=10.1133(2) Åb=10.1133(2) Å, c=16.7025(4) Åc=16.7025(4) Å, β=94.94(1)°β=94.94(1)°, V=1439.74(6) Å3V=1439.74(6) Å3 and MIL-64 crystallizes in the monoclinic space group C2/m (n° 12) with a=19.2227(1) Åa=19.2227(1) Å, b=12.2190(2) Åb=12.2190(2) Å, c=12.7008(2) Åc=12.7008(2) Å, β=129.239(1)°β=129.239(1)° and V=2310.52(5) Å3V=2310.52(5) Å3. Both structures exhibit a three-dimensional framework. For ULM-4, it consists of hexameric units Al3(PO4)3F2 in which the aluminium atoms exhibits two types of surrounding (one octahedron, AlO4F2 and two trigonal bipyramids, AlO4F). The fluorine atoms link the aluminium atoms together. This building unit is similar to that observed in the iron and gallium analogues. The connection of the hexameric units delimits rectangular-shaped 10-ring channels along [010] and 8-ring channels along [100] in which the 1,3-diaminopropane molecules are located. The subnetwork of the amines induces a non-centric symmetry. The second compound MIL-64 is composed of inorganic layers consisting of infinite zigzag chains corner-sharing (via fluorine) aluminum octahedra (AlO4F2, AlO2F3(H2O) and AlO3F2(H2O)) with the cis–trans sequence, connected to each other through fluorine and phosphate groups. The resulting sheets are linked to each other via additional AlO4 and PO4 tetrahedral units and this generates a three-dimensional network with cavities, encapsulating the molecular species OH2⋯H2N(CH2)NH3/OH⋯H3N(CH2)NH3.

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