Pseudopeptidic Coordination Polymers Based on Zirconium-Carboxylate Supramolecular Assemblies

Abstract

Mimicking enzymes with new materials is a promising approach to improve efficiency and sustainability in heterogeneous catalysis. In this contribution, a family of coordination polymers based on N, N'-bis(amino acid)pyromellitic diimide linkers and Zr-oxo clusters has been assembled under solvothermal conditions in the presence of different acids (acetic, hydrochloric, and formic acid). The linker has been prepared from widely available amino acids and pyromellitic anhydride under microwave conditions. Different characterization techniques, such as NMR, Fourier transform infrared spectroscopy (FTIR), TGA, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM)/EDX, confirmed the formation of the pseudopeptidic (PSP) linkers and the subsequent formation of Zr-carboxylate bonds in the Zr-PSP coordination polymer, forming regular homogeneous nanoparticles with hybrid inorganic-organic composition. The PSPs have also been incorporated into defective UiO-67 crystals and employed as catalysts in the hydrolysis of p-nitrophenylacetate under mild conditions, exhibiting a correlation between porosity, residue volume, and activity.