Hydrazone Based Dual - Responsive Colorimetric and Ratiometric Chemosensor for the Detection of Cu2+/F- Ions: DNA Tracking, Practical Performance in Environmental Samples and Tooth Paste.

Colorimetric sensors have attracted wide scope of attentions due to its fascinating advantages, like handy, equipment-free and naked eye detections. In this investigation, a new and novel hydrazone based dual-responsive ratiometric/colorimetric chemosensor have been developed for highly selective and sensitive detection of Cu2+ and F- ions in dimethyl sulfoxide (DMSO) solvent. The probe showed highly selective sensing towards Cu2+ and F- ions by exhibiting a color change from pale yellow to yellowish green and pale yellow to yellowish brown respectively., in DMSO without any interference of other ions at same concentration. These experimental results have also substantiated by the NMR, HR-MS, UV-Vis spectroscopic, cyclic voltammetry, differential pulse voltammetry techniques and DFT calculations. The detection limits are found to be 5.8 μM for Cu2+ and 0.025 μM for F- ions which is far below to the values recommended by WHO. The stoichiometric ratios between NAPCBH and Cu2+/ F- ions were confirmed from the Job's plots and 1H NMR titration experiments which are found to be 2:1 and 1:1 respectively. The tracking ability of the DNA with NAPCBH-Cu2+ was studied by UV-Vis titration and Cyclic voltammetry measurements. It shows efficient affinity towards DNA with NAPCBH-Cu2+. The probe can also quantitatively determine the Copper and fluoride ions present in environmental samples & toothpaste. The NAPCBH was promptly recovered by utilizing very low concentration of HCl, showing that was found feasible and re-usable sensor for the convenient detection of Cu2+ and F- ions. Graphical Abstract.