Synthesis, structure and properties of zinc(II) coordination polymers with 9H-carbazole-2,7-dicarboxylic acid

Abstract

From a new dicarboxylate ligand, 9 H -carbazole-2,7-dicarboxylic acid (2,7-H 2 CDC), three Zn(II) metal-organic frameworks were synthesized in the absence or presence of ditopic N-donor ligands. They are formulated as [Zn 5 ( μ 3 -OH) 2 (2,7-CDC) 4 (DEF) 2 ] ( 1 ) (DEF= N , N -diethylformamide), [Zn 2 (2,7-CDC) 2 (DABCO)(H 2 O)]·5DMF·H 2 O ( 2 ) (DABCO=1-diaza-bicyclo[2.2.2]octane, DMF= N , N -dimethylformamide), and [Zn 2 (2,7-CDC) 2 (bpea)]·3DMA·2 H 2 O ( 3 ) (bpea=1,2- bis (4-pyridyl)ethylane, DMA= N , N -dimethylacetamide). Compounds 1 and 3 display the 3D pcu frameworks. In 1 the unusual pentanuclear [Zn 5 ( μ 3 -OH) 2 (COO) 8 ] secondary building units (SBUs) are linked by dicarboxylate ligands. Differently, in 3 the well-known paddle–wheel [Zn 2 (COO) 4 ] SBUs are linked by dicarboxylate and dipyridyl ligands. Compound 2 shows the rare self-catenated 3D alb -3,6-C2/c net topology based on the dinuclear paddle–wheel SBU and a mononuclear unit. The stability and fluorescent properties of the compounds have been studied. A new dicarboxylate ligand, 9 H -carbazole-2,7-dicarboxylic acid, was used to construct Zn(II) metal-organic frameworks, including a novel self-catenated network with the rare 3D alb -3,6-C2/c net and two pcu -type networks based on an unprecedented pentanuclear clusters and the common paddle–wheel units. The compounds show blue fluorescent properties. • MOFs with a new carbazole-based dicarboxylate ligand. • New pentanuclear [Zn 5 ( μ 3 -OH) 2 (COO) 8 ] secondary building unit. • The rare self-catenated 3D alb -3,6-C2/c net.