Flexible and versatile anionic modules in the direction of 1-D, 2-D, and 3-D coordination frameworks by metal–ligand synergistic interactions

Abstract

This work presents the structural assemblies of a series of coordination polymers by utilizing the familiar metal ions with two flexible and versatile pyridylcarboxylate derivative ligands as anionic building blocks, namely, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thioacetate and its 3-N-pyridyl isomer. These complexes display multifarious polymeric coordination frameworks, such as the 1-D double-strand chain, 2-D homochiral layer, as well as 3-D (3,6)-connected networks with anatase or rutile topology, in which the unsymmetric organic modules may serve for two-connected spacers (for 1-D and 2-D species) or three-connected nodes (for 3-D species) with dissimilar coordination modes and configurations. Apparently, the metal centers also play a critical role in facilitating the structural diversity by adopting different network linkages. Hydrogen-bonding contacts are generally found to extend and/or stabilize the overall crystalline lattices when aqua molecules are available.