Porous coordination cages, also commonly referred to as metal-organic polyhedra (MOPs) or nanoballs, a closely related set of materials to metal-organic frameworks, are discrete cages with potentially unique porosity and solubilities compared to 2 and 3 dimensional frameworks. Many isophthalic acid- and copper(II)-based cages have been prepared via typical solvothermal synthesis, and post-synthetic modification via ligand exchange has also been established. However, the ligand exchange process in these materials is poorly understood. Herein, the kinetics and thermodynamics of ligand exchange between 5-hydroxyisophthalic acid and insoluble isophthalic acid analogs are investigated. 5-hydroxyisophthalic acid copper(II) coordination cage is soluble in methanol, and as ligands are exchanged with isophthalic acid, crystallization begins to occur and insoluble precipitate forms. Using UV-vis, infrared, and NMR spectroscopy, kinetic and equilibrium experiments were performed in order to gain insight into the formation of the mixed-ligand polyhedra. The resulting crystals were characterized via single crystal X-ray crystallography and NMR digestions to confirm ligand ratios, and porosity was assessed via gas adsorption.<br/>

Understanding the kinetics and thermodynamics of ligand exchange in porous molecular cages

256th National Meeting (2018)

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