An Isoniazid-Based reversible Schiff base chemosensor for Multi-Analyte (Cu2+, Ni2+, Hg2+) detection

Isoniazid-based Schiff base N’-(furan-2-ylmethylene)isonicotinohydrazide (FINH) has been synthesized. FINH has proven its ability to selectively sense and respond to Cu²⁺, Ni²⁺, and Hg²⁺, which shows its potential as a chemosensor. UV–visible experiments, the absorption band (at 360 nm) of FINH shifted with the gradual addition of Cu²⁺, Ni²⁺, and Hg²⁺. A significant quenching in the emission band of FINH in fluorescence spectra has been observed with the addition of analytes at the physiological pH range. Cyclic voltammetric experiments have been conducted to determine the electron transfer process that occurs during the complexation of FINH with analytes. Moreover, the interactions of FINH-metal ions are reversible, and their reversible behavior has been demonstrated with the Na₂EDTA solution. The binding insights among FINH and Cu²⁺, Ni²⁺, and Hg²⁺ are explained by IR spectral study. Additionally, the FINH works within the appreciable detection limit of 9.472 x 10⁻⁷ M (for Cu²⁺), 7.685 x 10⁻⁷ M (for Ni²⁺) and 2.411 x 10⁻⁷ M (for Hg²⁺), limit of quantitation of 3.15 x 10⁻⁶ M (for Cu²⁺), 2.561 x 10⁻⁶ M (for Ni²⁺) and 8.036 x 10⁻⁷ M (for Hg²⁺). Applying this isoniazid-based reversible chemosensor in analyzing real samples demonstrates its practicality and effectiveness for multi-analyte detection. This sensor could consistently measure metal ion concentrations in various environmental and biological samples, providing a valuable tool for monitoring pollutants and evaluating exposure risks.