Construction of five Zn(ii)/Cd(ii) coordination polymers derived from a new linear carboxylate/pyridyl ligand: design, synthesis, and photocatalytic properties.

Solvothermal reactions of Cd(OAc)2/Zn(OAc)2 with a new ligand, (pyridin-3-yl)methyl 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoate (L1), under different templates via an in situ ligand transformation reaction produced five coordination polymers, [CdL2(H2O)]n (1), [Cd1.5L3]n (2), [Cd2L4]n (3), [(ZnL2)·H2O]n (4) and {[Zn(1,3-BDC)(L1)]·MeCN·0.5H2O}n (5), where HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid. Compound 1 is a three-dimensional (3D) wave-like structure constructed from 4-connected Cd(ii) nodes and L(-) linkers. Compounds 2 and 3 bear similar 2D networks built from metallocyclic [Cd4L4] units. Compound 4 features a wrinkled 2D layer based on metallocyclic [Zn4L4] units. Compound 5 has a novel 1D single-wall metal-organic nanotube (SWMONT) in which the 1,3-BDC ligands act as linkers to connect the [Zn2(L1)2] rings. The results reveal that the different templates have a significant effect on the final structures. Compounds 1-5 exhibited relatively high photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV-Vis irradiation. The kinetics of the catalytic photodegradation reactions and the stabilities of photocatalysts were also investigated.