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

Three porous lanthanide−organic frameworks, [Ln4(OH)4(3-SBA)4(H2O)4]·nH2O [Ln = EuIII (1), n = 10; GdIII (2), n = 10; TbIII (3), n = 8; 3-SBA = 3-sulfobenzoate], have been prepared by a hydrothermal synthesis method. They are isomorphous and crystallize in a tetragonal system with space group P 421c. The structure can be considered to be built up by cubanelike [Ln4(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 [Ln4(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 Schläfli symbol of (43)4(420.628.818). The luminescent properties of the EuIII (1) and TbIII (3) complexes have been studied, showing characteristic emissions at room temperature. Variable-temperature magnetic susceptibility studies indicate that the GdIII complex 2 displays weak antiferromagnetic coupling through μ3-OH− pathways.