Rapid sequential detection of Al and glyphosate using an "Off-On-Off" fluorescent probe based on salicylate modified layered double hydroxides.

A fluorescent probe based on salicylate modified layered double hydroxide (LDH-SA) is presented, enabling the swift sequential detection of Al, fosetyl-Al and glyphosate in aqueous environment. The probe was synthesized using a simple co-precipitation procedure, and its properties and synthesis conditions were thoroughly characterized and optimized. A unique "off-on-off" fluorescent response was observed when the probe sequentially interacted with Al and glyphosate, and the detection method based on this phenomenon was established. The limits of detection for Al and glyphosate were determined as 0.03 μmol/L and 0.03 mg/L, respectively, with rapid detection periods of one minute and four minutes. The LDH-SA/Al complex requires Al to generate a chelation-gathered fluorescence effect, which is the mechanism by which it quenches LDH-SA. This is possible due to the inhibition of excited-state intramolecular proton transfer and photoinduced electron transfer processes within LDH-SA after incorporating Al. Upon interaction with glyphosate, competitive complexation between glyphosate and Al is initiated, which leads to a recovery of the fluorescence spectrum of LDH-SA and demonstrating the "off-on-off" behavior. An "INHIBIT" logic gate system was devised utilizing the response, indicating potential applications in fluorescence-based devices. Such a rapid, sequential detection capacity is impressive. It attests to the utility of LDH-SA as a probe for Al or glyphosate, and suggests promise for applications in pollutant analysis or environmental monitoring applications.