Selective detection for methomyl pesticide via catalytic chemosensing assay

The catalytic chemosensing assay (CCA), a new indicator displacement assay, is developed for selective detection of methomyl, a highly toxic pesticide. Herein, a trimetallic complex, {Feˡˡ(dmbpy)(CN)₄–[Ptˡˡ(DMSO)Cl]₂–Ruˡˡ(bpy)₂(CN)₂}, 1, (dmbpy = 4,4’‐dimethyl‐2,2’‐bipyridine and bpy = 2,2’‐bipyridine) is synthesized as a task‐specific catalyst to initially reduce and degrade methomyl into CH₃SH/CH₃NH₂/CH₃CN/CO₂. The thus‐produced CH₃SH interacts with the trimetallic complex to displace the luminophore, cis‐Ruˡˡ(bpy)₂(CN)₂, for monitoring. Other pesticides, including organophosphates and similar carbamate pesticides, remained intact under the same catalytic conditions; a selective sensing signal is only activated when 1 recognizes methomyl. Furthermore, 1 can be applied to detect methomyl in real water samples. According to the luminescent mode of the assay, the method detection limit (MDL) of 1 to methomyl (LD₅₀ = 17 mg/kg) was 1.12 mg/L. Copyright © 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.