Synthesis, structure, luminescence and catalytic properties of cadmium(II) coordination polymers with 9H-carbazole-2,7-dicarboxylic acid
Two Cd(II) metal–organic frameworks were synthesized from the NH-functionalized dicarboxylate ligand 9H-carbazole-2,7-dicarboxylic acid (2,7-H2CDC). Compound 1, [Cd4(CDC)4(DMF)4]·4DMF·4H2O, displays 2D square grid networks based on novel tetranuclear [Cd4(COO)8] secondary building units (SBUs) and pairwise CDC2− linkers. Compound 2, (H3O)2[Cd3(2,7-CDC)4]·3DMF·4H2O, is also based on 4-connected SBUs and pairwise CDC linkers, but the unusual trinuclear [Cd3(COO)8] SBUs lead to 2-fold interpenetrated 3D diamond-type frameworks with guest accessible voids. Both compounds display strong blue fluorescence in the solid state, and compound 2 shows high catalytic activity for Knoevenagel condensation.