Synthesis and characterisation of new coordination polymers by combining 2-pyridyl oximes or alcohols with functionalised terephthalic acid analogues

Isolation of mixed-ligand compounds has attracted considerable research interest as the synergy between ligands results in species with interesting technological, environmental and biomedical applications. In this study, initial employment of 2-pyridyl oximes or 2-pyridyl alcohols in combination with 2-hydroxyterephthalic acid (H 3 MHBDC) and 2,5-dihydroxyterephthalic acid (H 4 DHBDC) has yielded a new family of 1D coordination polymers and a metal cluster, namely [M(H 2 pyaox) 2 (H 2 DHBDC)] n (M = Zn, 1 ; Mn, 2 ), [Co 3 (mpko) 4 (Hmpko) 2 ](H 2 DHBDC) 2 ·2DMF ( 3 ·2DMF), [M(Hhmp) 2 (H 2 DHBDC)] n ·DMF (M = Ni, 4 ·DMF; Zn, 5 ·DMF), [Ni(H 2 pyaox) 2 (HMHBDC)] n ·2DMF ( 6 ·2DMF), and [Zn(Hmpko) 2 (HMHBDC)] n ·DMF ( 7 ·DMF), where H 2 pyaox = pyridine-2-amidoxime and Hmpko = 2-methyl pyridyl ketoxime. 1-7 are the first compounds bearing a 2-pyridyl oxime or 2-pyridinemethanol (Hhmp) with H 3 MHBDC or H 4 DHBDC in their neutral or anionic form. Notably, 4 exhibits a high capacity for Co 2+ uptake (900 mg Co 2+ g −1 4 ), which can be attributed to the presence of free coordination sites in the carboxylate linker. The combination of 2-pyridyl oximes or 2-pyridinemethanol and a hydroxo-functionalized dicarboxylic acid has provided access to a family of coordination polymers.