Electrocatalytic N-C-N coupling over a hierarchically ordered open single-atom superstructure toward organonitrogen synthesis.

Abstract

Electrochemically constructing C-N and N-C-N bonds provides an economical and sustainable alternative to conventional chemosynthesis. Herein, a hierarchically ordered open superstructure of N-doped carbon isolated with accessible three-coordinated Zn single-atom sites is explored for efficient electrocatalytic N-C-N coupling. Benefiting from the distinctive structural merits, this catalyst enables electrocatalytic preparation of N-C-N bonded compounds from methanol and amines. Notably, the Faradaic efficiency and selectivity of N,N,N',N'-tetramethyldiaminomethane reach up to 77% and 96% at 0.8 V, respectively. Further integrating the aminoalkylation reaction, an electro-thermo cascade synthesis is explored with the electrochemically obtained N,N,N',N'-tetramethyldiaminomethane serving as a unique reagent, leading to a specific set of organonitrogen compounds with (dimethylamino)methyl substituent, including topotecan hydrochloride, an anti-tumor drug, with a high yield of 95%. Furthermore, the in situ spectroscopic characterization and calculations unveil that the under-coordinated Zn-N₃ sites play a pivotal role in stabilizing the key *CH₂O intermediate, thereby facilitating subsequent nucleophilic addition with amines.