Design and chemical synthesis of a novel coumarin-based framework as a potential chemosensor of a neurotoxic insecticide, azamethiphos

A selective affinity of a novel coumarin-functionalized fluorescent sensor, 8-((E)-((thiophen-2-yl)methylimino)methyl)-7-hydroxy-4-methyl-2H-chromen-2-one (L) to copper (II) ion via fluorescence quenching in HEPES buffer at pH 7.4 has been demonstrated. This coordination chemistry between the coumarin-based ligand L and copper (II) ion has been subsequently exploited for the generation of a unique chemical ensemble, L.Cu2+, which qualifies the former as a sensitive and selective fluorogenic sensor for the toxic organophosphate pesticide, azamethiphos. The sequestering of the native fluorescence of receptor probe L, upon an entrapment of copper (II) within the former, was altered upon a sequential administration of azamethiphos into the environment of the host complex, L.Cu2+. The physico-chemical interactions between the sensor complex L.Cu2+ and azamethiphos, as corroborated by 31P NMR studies and fluorescence spectroscopy, serves as the basis for an ideal chemical discrimination of azamethiphos, amongst a pool of several ecotoxic organophosphate pesticides.