A Trigonal Prismatic Ligand in the Metal-Mediated Self-Assembly of One- and Two-Dimensional Metallosupramolecular Polymers

A novel trispyrazine-pillared prismatic bicycooxacalixaromatic ligand <b>L</b> is synthesized, and its application in metal-mediated self-assembly is described. Under self-assembly conditions, single chain, double-stranded cross-linked coordination polymer and two-dimensional (2D) coordination polymeric networks were formed via <b>M</b>-<b>L</b> (Ag<sup>+</sup>, Cu<sup>2+</sup>, and Zn<sup>2+</sup>) coordinative interactions. Structural analyses revealed that the antiparallelly arranged one-dimensional coordination polymers (Cu<sup>2+</sup> and Zn<sup>2+</sup>) are arranged to generate well-defined voids to host aromatic guests (benzene) via C–H···π and π···π interactions, while the double-stranded cross-linked coordination polymer (Ag<sup>+</sup>) contains a rhomboidal [<b>Ag</b><sub><b>2</b></sub><b>(L</b><sup><b>3</b></sup><b>)</b><sub><b>2</b></sub>] (<b>L</b><sup><b>3</b></sup>: tridentate ligand) cage motif to include a benzene guest; the “thicker” (thickness: <i>ac</i> 5 Å) 2D coordination polymeric networks (Ag<sup>+</sup>, Cu<sup>2+</sup>, and Zn<sup>2+</sup>), however, are all formed by connection of one or two kinds of topologically different metallomacrocyclic cage units. These unique metallomacrocyclic cage units in the 2D coordination polymeric networks are capable of hosting different guest species. For instance, the rhomboidal [<b>M</b><sub><b>2</b></sub><b>(L</b><sup><b>3</b></sup><b>)</b><sub><b>2</b></sub>] (M = Ag<sup>+</sup>, Cu<sup>2+</sup>) cage units were found to host a benzene or a nitrate anion; a hexahedral [<b>M</b><sub><b>3</b></sub><b>(L</b><sup><b>3</b></sup><b>)</b><sub><b>3</b></sub>] (M = Ag<sup>+</sup>) cage was found to host a ligand <b>L</b> or a DMF molecule; the hexahedral [<b>M</b><sub><b>4</b></sub>(<b>L</b><sup><b>3</b></sup><b>)</b><sub><b>4</b></sub>] (M = Cu<sup>2+</sup>) cage was found to host four solvent molecules of benzene; and the rectangular [<b>M</b><sub><b>3</b></sub>(<b>L</b><sup><b>3</b></sup><b>)</b><sub><b>3</b></sub>] (M = Cu<sup>2+</sup>, Zn<sup>2+</sup>) cage units, however, were found to host two THF molecules. The results highlight the potential of ligand <b>L</b> for applications in the construction of “thicker” 2D coordination polymeric networks with well-defined metallomacrocyclic cage units capable of hosting various guest species.