Metal-organic frameworks based on uranyl and phosphonate ligands.
Three new crystalline metal-organic frameworks have been prepared from the reaction of uranyl nitrate with nitrilotris(methylphosphonic acid) [H6nmp, N(CH2PO3H2)3], 1,4-phenylenebis(methylene)diphosphonic acid [H4pmd, C6H4(PO3H2)2], and (benzene-1,3,5-triyltris(methylene))triphosphonic acid [H6bmt, C6H3(PO3H2)3]. Compound [(UO2)2F(H3nmp)(H2O)]·4H2O (I) crystallizes in space group C2/c, showing two crystallographically independent uranyl centres with pentagonal bipyramidal coordination geometries. While one metal centre is composed of a {(UO2)O3(μ-F)}2 dimer, the other comprises an isolated {(UO2)O5} polyhedron. Compound [(UO2)(H2pmd)] (II) crystallizes in space group P21/c, showing a centrosymmetric uranyl centre with an octahedral {(UO2)O4} coordination geometry. Compound [(UO2)3(H3bmt)2(H2O)2]·14H2O (III) crystallizes in space group P\bar 1, showing two crystallographically independent uranyl centres. One uranyl centre is a {(UO2)O5} pentagonal bipyramid similar to that in (I), while the other is a {(UO2)O4} centrosymmetric octahedron similar to that in (II). Compounds (I) and (III) contain solvent-accessible volumes accounting for ca 23.6 and 26.9% of their unit-cell volume, respectively. In (I) the cavity has a columnar shape and is occupied by disordered water molecules, while in (III) the cavity is a two-dimensional layer with more ordered water molecules. All compounds have been studied in the solid state using FT-IR spectroscopy. Topological studies show that compounds (I) and (III) are trinodal, with 3,6,6- and 4,4,6-connected networks, respectively. Compound (II) is instead a 4-connected uninodal network of the type cds.
Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal.
Bernardo
B
Monteiro
CICECO, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
José A
JA
Fernandes
Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal.
Cláudia C L
CC
Pereira
CICECO, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Sérgio M F
SM
Vilela
QOPNA, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
João P C
JP
Tomé
Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, 2695-066 Bobadela LRS, Portugal.
Joaquim
J
Marçalo
CICECO, Departamento de Química, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
Filipe A
FA
Almeida Paz
metal-organic frameworks; phosphonate ligands; uranyl ligands