Partial oxidation of cyclohexene over histidine-modified Cu-UiO-66 under aerobic conditions

• Copper(II) incorporation into post-synthetically functionalized UiO-66. • Cu(II) ions prefer Zr-O nodes over histidine in UiO-66. • DFT assisted X-ray absorption spectroscopy clarifies Cu(II) binding sites. • Cyclohexene oxidation to alcohol/ketone with high selectivity. • Confined Cu species vital for substrate transformation. Enzyme-inspired catalysis is an attractive approach for developing selective hydrocarbon partial oxidation processes. Here, histidine was introduced into defective UiO-66 metal–organic framework by ligand exchange, followed by Cu(II) ion insertion. Density functional theory modeling combined with X-ray Absorption spectroscopy revealed that Cu(II) has a higher affinity for open Zr-O node sites than for histidine, leading to a series of materials where Cu(II) ions are predominantly anchored to the Zr 6 O 4 (OH) 4 nodes, while only minority fractions of Cu(II) are anchored to histidine. Catalytic testing for aerobic cyclohexene oxidation with tert -butyl hydroperoxide (t-BuOOH) in trifluorotoluene solution at 25 °C showed activity for cyclohexene oxidation to cyclohexenol and cyclohexenone, with high selectivity. Benchmark tests revealed that Cu and t-BuOOH are both essential for the reaction, yet t-BuOOH consumption was far inferior to product formation rates, suggesting a radical reaction pathway involving O 2 .