# Mn2+ and [Ru(bpy)3]2+ in UiO-67 metal organic frameworks enhance photocatalytic oxidation of benzylamine via an electron transfer pathway

## TL;DR

A new metal-organic framework containing Mn2+ and [Ru(bpy)3]2+ efficiently catalyzes light-driven oxidation of benzylamine under ambient conditions.

## Contribution

A bimetallic MOF with Mn2+ and [Ru(bpy)3]2+ is shown to enhance photocatalytic oxidation via dual electron and energy transfer pathways.

## Key findings

- UiO-67 Ru50-Mn10 achieves turnover numbers up to 634 for benzylamine oxidation under LED irradiation.
- The MOF outperforms homogeneous analogues and Mn-free versions by 1.6 to 1.8 times.
- Mechanistic studies reveal dual electron and energy transfer pathways influenced by solvent.

## Abstract

The selective oxidation of amines to imines is an essential transformation in many chemical syntheses. Driving such reactions with light and earth abundant catalysts is highly interesting in the context of solar light energy conversion and broadening the reaction scope in organic synthesis. The here reported bimetallic metal–organic framework (MOF), UiO-67 Ru50-Mn10, allows oxidation of benzylamine under ambient conditions via dual electron and energy transfer with oxygen. UiO-67 Ru50-Mn10 integrates [Mn(bpy)2(Cl)2] active sites and light-active [Ru(bpy)3]2+ photosensitizers at the linkers of the UiO-67 scaffold. The spatial organisation of photo and redox-active centres enables efficient charge separation and mass transport. Under 460 nm LED irradiation for 24 h and ambient aerobic conditions, UiO-67 Ru50-Mn10 catalyses the oxidation of benzylamine to N-benzylidene-1-phenylmethanamine with turnover numbers up to 634, which is 1.6 to 1.8 times higher than homogeneous analogues and the Mn-free UiO-67 Ru50. Structural and spectroscopic studies confirm successful incorporation of both metals, while mechanistic analyses reveal dual electron and energy transfer pathways, influenced by the solvent environment. This work highlights the potential of heterometallic MOFs with earth-abundant catalytic sites as efficient platforms for photocatalytic oxidative transformations.

A UiO-67 MOF functionalized with [Ru(bpy)3]2+ and Mn2+ ions is active in light-driven amine oxidation. The oxidation via photosensitized singlet oxygen and electron transfer to manganese was evaluated.