Abstract:
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) ions 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) ions has been subsequently exploited for the generation of a unique chemical
ensemble, LCu2+, which qualifies the former as a sensitive and selective fluorogenic sensor for the toxic
organophosphate pesticide azamethiphos in aqueous medium. The sequestering of the native fluorescence
of receptor probe L upon entrapment of copper(II) within the former was altered upon sequential
administration of azamethiphos into the environment of the host complex, LCu2+. The physico-chemical
interactions between the sensor complex LCu2+ and azamethiphos, as corroborated by 31P NMR studies
and fluorescence spectroscopy, serve as the basis for ideal chemical discrimination of azamethiphos,
amongst a pool of several ecotoxic organophosphate pesticides.
