Coumarinyl thioether Schiff base as a turn-on fluorescent Zn(ii) sensor and the complex as chemosensor for the selective recognition of ATP, along with its application in whole cell imaging

Abstract

The coumarinyl thioether Schiff base, H₂L, demonstrates turn-on fluorescence sensing towards Zn²⁺ ion with a limit of detection (LOD) of 0.068 μM. Different physicochemical techniques (mass, ¹H NMR, Job's) support the formation of a 1 : 1 metal-to-ligand complex, [ZnL]. The fluorogenic complex [ZnL] recognizes ATP in the presence of all other common anions, inorganic phosphates and biologically important phosphates (nucleosides, nucleotides). The proposed sensor has efficiently been used for ATP sensing with a LOD of 6.7 μM, which is the lowest in literature. Exogenous zinc ions in SCC084 (human oral carcinoma) cells have been checked through fluorescence cell imaging process by adding H₂L in the medium.