Stable Acrylamide-Linked Covalent Organic Frameworks via Mannich Polymerization for Efficient Gold Recovery from...

Achieving both high stability and selectivity remains a critical challenge in covalent organic frameworks (COFs) for efficient gold recovery. Herein, we present a one-step Mannich-type three-component polymerization involving 1,3,5-triformylbenzene, Meldrum's acid, and aromatic diamines to construct a series of acrylamide-linked COFs (TFB-PD-M, TFB-ND-M, and TFB-AD-M). The incorporation of acrylamide linkages enhances π-conjugation and backbone rigidity, thereby yielding COFs with high crystallinity, permanent porosity, and exceptional chemical and thermal stability under extreme conditions. Importantly, the dual coordination sites (C═O and N─H) within the acrylamide units enable robust and selective Au³⁺ binding through synergistic hydrogen bonding and chelation. Notably, TFB-AD-M achieves 98.5% selective Au³⁺ recovery from complex electronic waste leachates, even in the presence of competing metal ions. This work introduces a robust linkage strategy that not only improves COF stability but also facilitates selective metal capture for resource recovery.