Stabilization of Photocatalytically Active Uranyl Species in a Uranyl-Organic Framework for Heterogeneous Alkane Fluorination Driven by Visible Light

When photoactivated, the uranyl ion is a powerful oxidant capable of abstracting hydrogen atoms from nonactivated C-H bonds. However, the highly reactive singly reduced [UVO2]+ intermediate is unstable with respect to disproportionation to the uranyl dication and insoluble tetravalent uranium phases, which limits the usage of uranyl ions as robust photocatalysts. Herein, we demonstrate that photoactivated uranyl ions can be stabilized by immobilizing and separating them spatially in a uranyl-organic framework heterogeneous catalyst, NU-1301. The visible-light-photoactivated uranyl ions in NU-1301 exhibited longer-lived U(V) and radicals than those in homogeneous counterparts, as evidenced by X-ray photoelectron spectroscopy and time-dependent electron paramagnetic resonance, leading to higher turnovers and enhanced stability for the fluorination of nonactivated alkanes.