A terpyridine-based molecular fluorescent sensor for the on-site detection of glyphosate and AMPA in surface water

The monitoring of glyphosate (GlyP), the most widely used herbicide in the world, and aminomethylphosphonic acid (AMPA), its primary degradation product, in surface water is a public health concern due to their association with various diseases and carcinogenicity. In this study, we describe a novel terpyridine derivative incorporating recognition moieties specific for carboxylate, phosphonic acid and amine functionalities present in glyphosate and AMPA. The fluorescent molecular probe was synthesised and then activated through the formation of a Zn(II) complex. The photophysical properties of the probe and its complexation abilities with target analytes in aqueous solution (MeOH/HEPES buffer mixture) were characterized using both experimental approaches and computational modelling based on (TD-)DFT. The fluorescent molecular probe displayed high selectivity and sensitivity for both analytes, with detection limits of 51 nM for glyphosate and 70 nM for AMPA. The two different mechanisms for glyphosate and AMPA, respectively, complexation, with a high log(β) of 6.8, and covalent binding, even allowed for sequential detection of both analytes from the same sample. Owing to its efficiency and robustness, the molecular probe was successfully integrated into an embedded sensor system, whose performance was validated by analyzing real water samples (e.g. river water) with high recovery rates.