Tuning the Mechanical Behavior of Metal-Phenolic Networks through Building Block Composition

Metal-phenolic networks (MPNs) are an emerging class of functional metal-organic materials with a high degree of modularity in terms of the choice of metal ion, phenolic ligand, and assembly method. Although various applications, including drug delivery, imaging, and catalysis, have been studied with MPNs, in the form of films and capsules, the influence of metals and organic building blocks on their mechanical properties is poorly understood. Herein, we demonstrate that the mechanical properties of MPNs can be tuned through choice of the metal ion and/or phenolic ligand. Specifically, the pH of the metal ion solution and/or size of phenolic ligand influence the Young's modulus ( E_Y) of MPNs (higher pHs and smaller ligands lead to higher E_Y). This study systematically investigates the roles of both metal ions and ligands on the mechanical properties of metal-organic materials and provides new insight into engineering the mechanical properties of coordination films.