Unique (3,12)-Connected Porous Lanthanide-Organic Frameworks Based on Ln4O4 Clusters: Synthesis, Crystal Structures, Luminescence, and Magnetism

Three porous lanthanide-organic frameworks, [Ln(4)(OH)(4)(3-SBA)(4)(H2O)(4)] center dot nH(2)O [Ln = Eu-III (1), n = 10; Gd-III (2), n = 10; Tb-III (3), n = 8; 3-SBA = 3-sultobenzoate], have been prepared by a hydrothermal synthesis method. They are isomorphous and crystallize in a tetragonal system with space group P (42) over bar (1)c. The structure can be considered to be built up by cubanelike [Ln(4)(OH)(4)](8+) secondary building units, which are further connected by 3-SBA to form a 3D coordination framework with 1D pores along the c direction for accommodation of novel T8(3) water tapes or zigzag water chains. Furthermore, in these compounds, the [Ln(4)(OH)(4)](8+) units and 3-SBA ligands serve as 12-connected and 3-connected nodes, respectively, resulting in a unique (3,12)-connected framework with the Schlafli symbol of (4(3))(4)(4(20).6(28).8(18)). The luminescent properties of the Eu-III (1) and Tb-III (3) complexes have been studied, showing characteristic emissions at room temperature. Variable-temperature magnetic susceptibility studies indicate that the Gd-III complex 2 displays weak antiferromagnetic coupling through mu(3)-OH- pathways.