Colorimetric/fluorescent/SERS triple-readout sensing of Mercury(Ⅱ) via in-situ growth of AgNPs in phenanthroline-functionalized covalent organic framework

Targeted design of new covalent organic frameworks (COFs) with specific functions to build multi-readout platform for environmental pollutant monitoring has been gaining increasing interest. Herein, a fluorescent phenanthroline-functionalized COF (PA-COF) with favorable pore structure and reactive nitrogen-containing functional groups is designed and synthesized, and in-situ growth of silver nanoparticles (AgNPs) in PA-COF is achieved to produce PA-COF-based nanocomposite ([email protected]). Phenanthroline facilitates the anchoring of Ag+ in the skeleton of COF material via strong coordination interaction, and the confinement of in-situ grown AgNPs on PA-COF structure provides excellent dispersibility. The formed silver amalgam in the skeleton of [email protected] with the presence of Mercury(II) can oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue product (oxTMB) quickly, inducing obvious absorbance/SERS signal enhancement and fluorescence quenching of [email protected] A colorimetric/fluorescence/SERS triple-readout strategy is thus developed for Hg2+ sensing with high sensitivity and excellent accuracy. The present study offers a promising strategy to develop a multi-readout assay platform for monitoring hazardous pollutants based on the targeted fabricating of novel COFs with specific functions.