Tuning the oxidative activity of copper-sites in Zr(IV)-C4 metal-organic frameworks

Copper-based homogeneous catalysts have repeatedly demonstrated the critical importance of precisely controlling the coordination environment of active sites to fine-tune their activity, efficiency, or selectivity— a versatility that is still far from being achieved in traditional copper catalysts supported on zeolite or aluminosilicate. This is precisely where metal–organic frameworks (MOFs) can make a difference, offering structural and chemical versatility that enables precise control over their pore environments. In this research, we have employed three new halide rich zirconium microporous MOFs, to later on stabilize copper ions with bromide and thiol rich coordination environments. These copper-based catalysts have thoroughly evaluated over the dopamine oxidation via hydrogen peroxide activation. Following the elucidation of the copper site characteristics using a combination of EPR, UV-Vis, XPS, and XAS spectroscopic techniques, a clear correlation was established between these features and their ability to activate hydrogen peroxide and oxidise dopamine. This work highlights the significant catalytic advantage offered by copper active sites featuring bromide- and thiol-rich coordination environments within MOFs. This approach differs markedly from conventional strategies, which typically rely on nitrogen- or oxygen-based ligands to stabilise metal ions in these microporous materials