Structural Diversity in Coordination Self-Assembled Networks of a Multimodal Ligand Azacalix[4]pyrazine

We report herein the synthesis of a new heteracalixaromatic compound, tetramethylazacalix[4]­pyrazine (TAPz), and its coordination self-assemblies with metal and metal cluster centers. Structural characterization of TAPz has shown that its conformation is fluxional in solution but exhibits a dominant 1,3-alternate configuration in the crystalline solid state, wherein its convergent chelating coordination sites are orthogonal to the 120°-angled bridging sites, thus forming a unique multimodal ligand. Compound TAPz reacting with silver, zinc metal centers, and CuxIx cluster centers leads to the construction of diverse coordination network structures in 1–5 including honeycomb, Kagomé, α-quartz, and cavity-involved two-dimensional layers. The structural diversity of these network structures is conducted by different combination modes between the chelation bonding sites of TAPz and metal or metal cluster centers. This system may afford deeper insight on the fantastic use of macrocyclic compounds on the designed synthesis of coordination network structures through the proper arrangement of their coordination sites.