Four 3D “brick-wall”-like metal–organic frameworks with a flexible ligand of (S,S,R,R)-1,2,3,4-cyclopentanetetracarboxylic acid: crystal structures, luminescent and magnetic properties†
Abstract
To investigate the conformation of cyclopentanetetracarboxylic acid, four new “brick-wall”-like metal–organic frameworks have been synthesized from hydrothermal reactions with different metal salts, (S,S,R,R)-1,2,3,4-cyclopentanetetracarboxylic acid (H4cptc) and auxiliary N-donor ligands, namely, Cu2(S,S,R,R-cptc)(bpe)(H2O)2·2H2O (1), Co2(S,S,R,R-cptc)(bpe)0.5(H2O)2·2H2O (2), Cd4(S,S,R,R-cptc)2(bpa)2(H2O)5·2H2O (3) and Co2(S,S,R,R-cptc)(bpy)0.5(H2O)2·2(H2O) (4) (bpe = 4-(2-(pyridine-4-yl)vinyl)pyridine, bpa = 4-(2-(pyridine-4-yl)ethyl)pyridine, bpy = 4-(pyridine-4-yl)pyridine). The complexes were further characterized by single-crystal X-ray diffraction, power X-ray diffraction, FT-IR spectra, fluorescent measurements and variable-temperature magnetic susceptibility measurements. The results of the structural investigations show that 1 is a charming (3,3,4)-trinodal architecture, 3 is an interesting trinodal (3,4,5)-connected architecture, and 2 and 4 are isostructural, which are both (4,5)-connected networks. In addition, the magnetic measurements indicate that 2 and 4 show weak antiferromagnetic interactions, and the fluorescent measurement shows the strong solid-state fluorescent emission at room temperature for 3.