Three Cd(II) coordination polymers based on a pyridyldicarboxylate: effect of coordinated water

Abstract

By systematic change of the solvothermal synthesis, three new coordination polymers, Cd(L)?(H₂O)]?2H₂O (1), Cd(L)?(H₂O)]?H₂O (2), and Cd(L)] (3), have been synthesized based on a tritopic ligand 4-(pyridin-3-yl)isophthalic acid (H₂L). Compounds 1 and 2 show very similar two-dimensional (2D) bilayers further linked by interlayer hydrogen bonds into three-dimensional (3D) supramolecular structures, while 3 displays a 3D structure constructed form one-dimensional (1D) Cd-carboxyl chains. Notably, 1 and 2 have a pair of unusual isomers with the opposite orientation of coordinated H₂O on the metal centers, leading to different hydrogen bonding interactions. Thermal stabilities and solid-state photoluminescences for 1–3 were also investigated.