Imidazole-based highly selective and sensitive carbonate anions chemosensor: Design, synthesis, characterization,...

The composition of a newly synthesized imidazole-based chemosensor (HL) and its carbonate adduct was established using spectral measurements (UV-Vis, IR, ¹H NMR, and mass). The receptor property of HL was examined in different cations and anions in MeOH-water (1:1 v/v), and HEPES buffer (50 mM at pH 7.4) showing fluorescence increase for CO₃^2- ion selectively. The receptor to carbonate binding stoichiometry was found to be 1:1 as ascertained by Job's plot and Benesi-Hildebrand plot. The simultaneous detection limit (LOD) and the binding constant of adduct formation were estimated to be 5.43 × 10^-7 M and 8.23 × 10³ M, respectively. The host-to-guest binding property was further verified by the proton NMR titration experiment. The selective and sensitive carbonate sensing property of HL is recognized by the electronic factors, (i) restricted free rotation of the C-C bond and (ii) blocking of the photoinduced electron transfer (PET). The present probe is non-cytotoxic and chemosensor activity towards CO₃^2- in mammalian cell lines (HepG2) is revealed by the cell imaging study.