Two new 3-D Cd(II) metal–organic frameworks based on flexible cyclohexane-1,2,4,5-tetracarboxylic acid ligand

Two new metal–organic frameworks, {[Cd2(CTA)(bpea)(H2O)3] (H2O)5}n (1) and {[Cd2(CTA)(bpe)1.5(H2O)2] (H2O)7}n (2) (H4CTA = cyclohexane-1,2,4,5-tetracarboxylic acid, bpea = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene), have been synthesized and characterized by elemental analysis, IR and X-ray powder diffraction. Single-crystal X-ray investigation reveals that two complexes possess three-dimensional frameworks, in which the carboxylate oxygen atoms on the H4CTA ligand display different coordination modes and all ligands exclusively keep same conformation. Thermogravimetric analysis shows that 1 and 2 represent favorable thermal stability. Moreover, two complexes exhibit purple emission in the solid state at ambient temperature.