Dipicolylaminofluorene Derivatives for Fluorescent Sensing of Copper(II) Ion and Glyphosate

The contamination of water by toxic herbicides poses a significant environmental challenge, necessitating the development of reliable detection tools. In this study, novel dipicolylamino derivatives of fluorene and fluorenone were synthesized via Sonogashira cross-coupling reactions with high yields. These compounds demonstrated exceptional selectivity for fluorescence turn-off by Cu(II) ions, with detection limits of 0.99 μM and 1.11 μM in a DMSO-HEPES buffer system. Investigations using Job's plot, fluorescence recovery with EDTA, and mass spectrometry revealed that the sensing mechanism involves complexation between the compounds and Cu(II) ions. Notably, the Cu(II)-fluorene complex exhibited a selective fluorescence turn-on response to glyphosate, achieving a detection limit of 0.93 μM. Quantitative analysis in real water samples demonstrated good recovery rates, underscoring the practical utility of these fluorene and fluorenone derivatives in environmental monitoring.