Covalent organic frameworks for ratiometric fluorescent monitoring copper corrosion in tin bronze

Metal corrosion has caused huge economic losses and security risks. Thus, fast and simple detection of metal corrosion are in high demand. Herein, strong yellow fluorescence covalent organic frameworks (Tma-Dmh-COF) with superior response to copper ions (Cu²⁺) was synthesized by 2,4, 6-trimethoxy-homophentriformaldehyde (Tma) and 2, 5-dimethoxy-p-phenylhydrazide (Dmh). On this basis, a sensitive and rapid fluorescent sensor for Cu²⁺ detection was proposed with the detection limit of 72 nmol L^-1. The fluorescence quenching effect of Tma-Dmh-COF was attributed to the strong coordination between the O,N,O'-chelating site in the pore wall of Tma-Dmh-COF and Cu²⁺. Moreover, using Tma-Dmh-COF as signal probe and silicon quantum dots (SiQDs) as reference probe, a ratiometric fluorescent sensor for Cu²⁺ was designed and successfully applied for monitoring early stages of metal corrosion in tin bronze. This work provided a facile strategy for the monitoring of metal corrosion.