Dual-mode fluorescence and electrochemiluminescence sensor based on functionalized EDTA-HOFs for ultrasensitive detection of Hg2.

Leveraging the unique properties of functionalized hydrogen-bonded organic frameworks (EDTA-HOFs), this study develops a dual-mode sensor platform-combining fluorescence and electrochemiluminescence-for the swift and sensitive detection of mercury ions (Hg2⁺) in homogeneous solutions. We use tris(4,4'-dicarboxy-2, 2'-bipyridine)ruthenium(II) [Ru(dcbpy)₃2⁺] as the signal emitter, introducing a heavy metal ion chelator (EDTA) into its structure and synthesizing the hydrogen-bonded organic framework compound EDTA-HOFs through intermolecular hydrogen bonding. EDTA-HOFs exhibit a large specific surface area and a robust hydrogen-bonding network, offering optimal N,N'-chelation sites for efficient metal ion recognition, thereby markedly improving the stability of both fluorescence (FL) and electrochemiluminescence (ECL) signals. Based on the synergistic interaction of multiple functional groups between EDTA and Hg2⁺, the sensor exhibits efficient and rapid "on-off" response characteristics for Hg2⁺ ions. Experimental results show that after interaction with Hg2⁺, the sensor generates significantly reduced ECL and FL signals, with a fluorescence detection limit (LOD) of 1.73 µM (0.1 nM to 1 µM) and an ECL detection limit of 0.27 pM (1 nM to 1 pM). Additionally, the sensor has been effectively applied to the electrochemical detection of Hg2⁺ in real samples (including lake water, rat serum, and the traditional Chinese medicine Sanqi), providing stable and reliable analytical results (RSD < 3.2%). This study presents an innovative synthetic strategy that opens new pathways for the preparation of novel functionalized hydrogen-bonded organic frameworks (HOFs) materials, while providing new theoretical foundations and technical insights for the development of trace-level Hg2⁺ ion sensors.