Selective photo-oxidative coupling of amines to form C–N bonds using post synthetic modification of MIL-68-NH2 with metal acetylacetonate

Abstract

Significant attention has been paid to the conversion of benzylamine into very valuable organic intermediates via selective photocatalytic oxidation. Due to their tremendous potential for light conversion and harvesting, metal–organic frameworks (MOFs) have received significant scientific interest in the field of photocatalysis. However, it is still difficult to photocatalyze organic reactions using MOFs under mild conditions. Here, we investigated the impact of modified MOFs with metal acetylacetonate (MIL-68-NH₂, MIL-68-AC-Ni, MIL-68-AC-Co, and MIL-68-AC-Fe) on the selective oxidation of benzylamine into N-benzylidene benzylamine with transformation percents of 36%, 91.8%, 95.1%, and 99.6%, respectively. For five reuses, high efficiency of the photocatalysts was shown. Based on the reactivity and kinetics of the reaction, a suggested mechanism for the photo-oxidation process has been developed. MIL-68-NH₂, MIL-68-AC-Ni, MIL-68-AC-Co, and MIL-68-AC-Fe had kinetic rates that exceeded the following values: 0.0061, 0.0142, 0.01618, and 0.01898 min⁻¹.