Adaptable coumarin-based fluorescent molecular multianalyte sensor for Zn, Hg and Cu different sensing modalities and its bioimaging applications.

A new organic coumarin-based probe, DCMC, was successfully designed and synthesized. Characterization techniques such as single-crystal X-ray diffraction, H-NMR, C-NMR, IR, and mass spectroscopy were used to analyse the chemical structure of this probe. Systematic sensing studies of DCMC in DMSO/HO (9/1, v/v, pH = 7.2) by fluorescence and absorption methods showed selectivity towards Hg, Zn and Cu by different sensing modalities. DCMC showed a distinctive red shift in UV-Vis spectra for Cu, while no similar response was observed for Hg and Zn. Additionally, it showed significant fluorescence quenching towards Hg, and for Zn, an eminent ratiometric fluorescence response was observed. The detection limit of DCMC towards Hg and Zn was calculated and established to be in the order of 10 (M), and for Cu, it was in the order of 10 (M). A detailed investigation was performed on the detection mechanism using Job's plot, H-NMR, ESI mass analysis and density functional theory (DFT) calculations, which established the 2 : 1 binding stoichiometry for all three ions. Further, a stability study was performed over a period of five days to establish the stability of DCMC prominently. The probe also coherently recognised the sensing cations in the solid state, making DCMC a portable kit for on-site detection. Besides, the live cell imaging study using the MCF-7 cell line to detect Zn and Hg revealed the detection capability of DCMC and its biocompatible nature. Finally, density functional theory and time-dependent density functional theory were implemented, which established the experimental outcomes theoretically.