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, [Cd-4(CDC)(4)(DMF)(4)]center dot 4DMF center dot 4H(2)O, displays 2D square grid networks based on novel tetranuclear [Cd-4(COO)(8)] secondary building units (SBUs) and pairwise CDC2- linkers. Compound 2, (H3O)(2)[Cd-3(2,7-CDC)(4)]center dot 3DMF center dot 4H(2)O, is also based on 4-connected SBUs and pairwise CDC linkers, but the unusual trinuclear [Cd-3(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.