Adaptable coumarin based fluorescent molecular multianalyte sensor for Zn2+, Hg2+ and Cu2+ via different sensing modalities and its bioimaging applications

Abstract

A new organic chromone based probe, DCMC was successfully designed and synthesized. Characterization techniques such as single crystal X-ray diffraction, 1H-NMR, 13C-NMR, IR, and mass spectroscopy have been used to analyse the chemical structure of this probe. The systematic sensing studies of DCMC in DMSO/H2O (9/1, v/v, pH = 7.2) by fluorescence and absorption method showed selectivity towards Hg2+, Zn2+ and Cu2+ by different sensing modalities. DCMC shows distinctive red shift in UV-Vis spectra for Cu2+ while no similar response was observed for Hg2+ and Zn2+. Additionally, it showed significant fluorescence quenching towards Hg2+ and for Zn2+, eminent ratiometric fluorescence response was observed. The detection limit of DCMC towards Hg2+ and Zn2+ was calculated and established to be order of 10-9 (M) and for Cu2+ it was in the order of 10-8 (M) respectively. A detailed investigation was performed on the detection mechanism by using Job’s plot, 1H-NMR, ESI mass analysis and density functional theory (DFT) calculations which established the 2:1 binding stoichiometry for all the three ions. Further the stability study was performed over a period of 5 days, to establish the stability of DCMC prominently. The probe also coherently recognised the sensing cations in solid state making DCMC a portable kit for onsite detection. Besides, the live cell imaging study on MCF-7 cell line to detect Zn2+ and Hg2+ also reveals 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.