Efficient Photocatalytic Oxidative Coupling of Benzylamine over Uranyl–Organic Frameworks

Abstract

Visible-light-driven organic transformation photocatalyzed by metal–organic frameworks (MOFs) under mild conditions is considered a feasible route to conserve energy and simplify synthesis. Herein, a light-sensitized, three-dimensional uranyl–organic framework (HNU-64) with twofold interpenetration and its derivatives HNU-64-CH3 and HNU-64-Cl with functionalized ligands of −CH3 and −Cl groups were obtained. These MOFs have broad optical absorption bands and suitable band energy levels in photooxidation, which makes them exhibit high activity and selectivity for the photooxidation of benzylamine to N-benzylbenzoimide under mild conditions. This work provides an efficient and simple synthetic option for oxidative coupling of amines to directly produce imines.

Linker Engineering for Reactive Oxygen Species Generation Efficiency in Ultra-Stable Nickel-Based Metal–Organic Frameworks

“…Imines are vital intermediates in the synthesis of pharmaceuticals and agrochemicals. − Visible-light-driven oxidative coupling of benzylamines has been established as an effective pathway to synthesize the corresponding imine products. The broad visible-light absorption and excellent chemical stability of the title Ni 8 -MOFs prompted us to study their potential as heterogeneous photocatalysts in aerobic oxidation reactions.…”

Introducing a Pyrazinoquinoxaline Derivative into a Metal–Organic Framework: Achieving Fluorescence-Enhanced Detection for Cs+ and Enhancing Photocatalytic Activity

“…Next, the benzylamine radical cation is consumed by O 2 .‑ and converted to benzylimine. Eventually, the product N-benzylbenzimidate is produced by coupling with benzylamine and releasing NH 3 . − …”

Photocatalytic Oxidative Amine Coupling with 4-Nitrophenylacetylene-Modified Cu2O Polyhedra

“…22 Moderate to good amine coupling yields have been demonstrated using uranyl-based MOFs. 23 Furthermore, a conjugated covalent organic framework (COF) with an electron-accepting benzothiadiazole moiety and an electron-donating pyrene unit can also perform photocatalytic oxidative amine coupling. 24 The COF synthesis took days at 120 °C.…”

“…A complicated polyoxometalate (POM)-based MOF incorporating Ru, Mo, and Cd ions also acts as a highly efficient photocatalyst for oxidative amine coupling . Moderate to good amine coupling yields have been demonstrated using uranyl-based MOFs . Furthermore, a conjugated covalent organic framework (COF) with an electron-accepting benzothiadiazole moiety and an electron-donating pyrene unit can also perform photocatalytic oxidative amine coupling .…”