1. Visible light-driven selective oxidation of amines by cooperative photocatalysis of niobium oxide nanorods with an electron–proton transfer mediator.
- Author
-
Ma, Xiaoming, Li, Xia, Wang, Yuexin, and Lang, Xianjun
- Subjects
- *
NIOBIUM oxide , *PHOTOCATALYSIS , *NANORODS , *OXIDATION-reduction reaction , *AMINES , *PROTON transfer reactions , *REACTIVE oxygen species , *ALCOHOL oxidation - Abstract
[Display omitted] • Nb 2 O 5 nanorods are synthesized with a specific surface area of 166 m2/g. • The dissociative adsorption of amine on Nb 2 O 5 affords a surface complex. • The surface complex can facilitate selective oxidation of amine to imine. • TEMPO+PF 6 − acts as an electron–proton transfer mediator. • Superoxide is the dominant reactive oxygen species. Cooperative photocatalysis has gained increasing interest to better an existing redox reaction with a mediator. Herein, an ingenious system is constructed for the visible light-driven selective oxidation of a variety of amines by merging niobium oxide (Nb 2 O 5) photocatalysis with an electron–proton transfer mediator, 2,2,6,6-tetramethylpiperidine-1-oxoammonium hexafluorophosphate (TEMPO+PF 6 −). The visible light-driven dissociative adsorption of amine over Nb 2 O 5 nanorods gives rise to an amine–Nb 2 O 5 complex with a weak response to visible light (λ < 460 nm). With adding 4 mol% of TEMPO+PF 6 −, the conversion of benzylamine over Nb 2 O 5 is approximately 2.5 times that without TEMPO+PF 6 −. The proton and electron transfer between the amine–Nb 2 O 5 complex and TEMPO+PF 6 − is the key to assuring cooperative photocatalysis. Besides, the oxidant dioxygen is predominantly reduced to superoxide anion in affording the imine products. This work highlights it is feasible to ameliorate selective organic conversions over metal oxide photocatalysts with a suited mediator. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF