A new carbazole-chalcone based chemosensor: Fluorescence<i> "turn</i><i>-on</i><i>-off</i><i>-on"</i> applications for OH-anion DFT calculation, docking studies, in living cells and real food/environmental samples

Carbazole-chalcone derivative fluorescent chemosensor (CRB1) was successfully synthesized and characterized to recognize the effect on OH- ion. CRB1 showed an "on-off-on" specific response towards OH- among different competing cations and anions. The detection process of orange color of sensor CRB1 selectively quenching at 563 nm in the presence of OH- anion was monitored. Sensor CRB1 was observed to realize the lowest detection limit of 0.19 mu M and the binding constant of 4.91 x 105 M- 1 for the detection of OH- . The binding ability of sensor CRB1 with OH- was demonstrated using fluorometric, UV-Vis, and 1H NMR titrations, reversibility with EDTA, Job's plot, docking study, and density functional theory studies (DFT). Furthermore, selectivity experiments of OH- anion were performed, test strips, real food sample, and environmental analysis to determine the practical applicability of the sensor. Additionally, the activities of CRB1 in three different cell lines (MCF-7, MDA-MB-231, and WI-38) were examined.