Multi-ion detection and molecular switching behaviour of reversible dual fluorescent sensor

Abstract

The selective chemosensing behaviour of imidazole bisthiocarbohydrazone (IBTC) towards F− and Cu2+ are studied via colorimetric, UV–Visible, fluorescence spectra studies, and binding constants were calculated. The 1H NMR titration study strongly support that the deprotonation of IBTC followed by the hydrogen bond formation via N1H1 and N2H2 protons with fluoride ion. The fluorescence inactive IBTC-Cu complex became fluorescence active in the presence of perchlorate (ClO4−) ion. The selective detection of perchlorate ion was also explained. The F− sensing mechanism of IBTC has been investigated by Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) methods. The theoretical outcomes well reproduce the experimental results. And it concluded the NH protons, nearby the imine group was first captured by the added F− ion and then deprotonation happened followed by the formation of hydrogen bond. The IBTC found good reversibility character with the alternative addition of Ca2+ and F−. The multi-ion detection of IBTC was used to construct the NOR, OR and INHIBITION molecular logic gates.