Eight Two-Dimensional and Three-Dimensional Metal−Organic Frameworks Based on a Flexible Tetrakis(imidazole) Ligand: Synthesis, Topological Structures, and Photoluminescent Properties

Eight new metal−organic frameworks based on the tetrakis(imidazole) ligand tetrakis(imidazol-1-ylmethyl)methane (L), namely, [Zn 2 (L)(SO 4 ) 2 ]·2H 2 O ( 1 ), [Co(L)(SO 4 )]·1.25H 2 O ( 2 ), [Zn 2 (L)(L 1 ) 2 ]·3.5H 2 O ( 3 ), [Co 2 (L)(L 1 ) 2 ]·2.5H 2 O ( 4 ), [Zn 2 (L)(L 2 )(H 2 L 2 ) 2 ]·5H 2 O ( 5 ), [Co 1.5 (L)(L 2 )] ( 6 ), [Zn 2 (L)(L 3 )]·4H 2 O ( 7 ), and [Co(L)(H 2 O) 2 ]·(H 2 L 3 )·1.5H 2 O ( 8 ), where H 2 L 1 = 1,4-benzenedicarboxylic acid, H 3 L 2 = 1,3,5-benzenetricarboxylic acid, and H 4 L 3 = 1,2,4,5-benzenetetracarboxylic acid, have been synthesized under hydrothermal conditions. Compounds 1 and 2 were isolated by the reactions of L with inorganic SO 4 2− anions. Compound 1 displays a 2-fold interpenetrated PtS net. Compound 2 possesses a binodal (4,6)-connected topology with the Schläfli symbol of (3·4·5 3 ·6)(3 2 ·4·5 4 ·6 7 ·7). Compounds 3 − 8 have been obtained by the reactions of L with organic carboxylate ligands. Compound 3 shows a trinodal (3,4)-connected topology with the Schläfli notation of (6 6 )(6 5 ·8)(6 3 ). Compound 4 is isostructural with 3 . The compound 5 is a binodal (3,4)-connected two-dimensional (2D) net with the the Schläfli notation of (6 2 ·8) (4·6 4 ·8). 6 shows a trinodal (3,4)-connected framework with the Schläfli symbol of (4·8 2 ) 2 (4 2 ·8 4 )(8 4 ·12 2 ). Compound 7 exhibits a pentanodal net with the Schläfli symbol of (4·6·8 4 )(4 2 ·6 4 )(4 2 ·8 4 )(4 2 ·8 3 ·10)(4·6 2 ·8 3 ). Compound 8 is a rare 4-connected 2D net with the Schläfli symbol of (4 3 ·6 3 ). The influence of the metal atoms and ligands on the structures of the coordination polymers has been discussed. The infrared spectra, thermogravimetric analysis, and luminescent properties were also investigated for the compounds.