Möbius Aromatic Figure-Eight Knotted Three-Dimensional Covalent Organic Frameworks

Abstract

Möbius aromaticity extends the concept of aromaticity into the topological dimension. However, the synthesis of well-defined molecular systems with this unique property, especially the assembly into infinite polymeric networks, remains a significant challenge due to uncontrolled ring-strain effects. Herein, we report the synthesis of a Möbius aromatic hexa[2,3-thienylene] macrocycle (HTE) with a striking figure-eight shape and the control sample of tetra[2,3-thienylene] (TTE) with an antiaromatic nature, which is further assembled into the extended 3D covalent organic frameworks (COFs) of NUST-67 and NUST-66. The Möbius aromaticity of HTE can modulate the oxidation potential, lower the p-band center of active sites, and weaken the adsorption strength of the *OOH intermediate. As a result, the obtained NUST-67, with a thermodynamically optimized reaction pathway and kinetically enhanced mass/charge transfer, exhibits much superior electrocatalytic activity and selectivity toward H2O2 reduction with industrial-grade performance than NUST-66, featuring a current density window of 100–400 mA cm–2 and an H2O2 Faradic efficiency exceeding 88%. This study discloses the first integration of a Möbius aromatic unit into a COF and elucidates the working effect of aromaticity by a targeted electrocatalytic probe, which establishes a new paradigm for designing organic electrocatalysts by aromaticity engineering.