A turn-off sensory recognition of Fe3+ and Ru3+ metal ions with novel isoindoline-1,3-dione substituted Schiff base: A detailed theoretical and experimental overview

Abstract

In this study, we present the synthesis and characterization of a novel isoindoline-1,3-dione-substituted fluorophore, namely 2-[1-benzyl-2-(4-methoxy-phenylimino)-ethyl]-isoindole-1,3-dione (referred to as L), designed for the specific recognition of Fe3+ and Ru3+ metal ions through a fluorescence quenching mechanism. The obtained limit of detection values for Fe3+ and Ru3+ ions were determined to be 0.65 µM and 0.26 µM, respectively. Characterizations of the synthesized fluorophore (L) was achieved through a comprehensive suite of spectroscopic techniques, including 1H and 13C NMR, FT-IR, elemental analyses, and high-resolution mass spectrometry (HRMS). The spectroscopic data unequivocally support the structure and composition of the fluorophore. Fluorescence titration experiments revealed a 1:1 binding stoichiometry between the fluorophore (L) and both Fe3+ and Ru3+ metal ions. Furthermore, we harnessed the easily observable “naked eye” response of the fluorophore-metal ion complexes to develop a rapid, cost-effective, and straightforward on-site trace detection method utilizing paper strips. To gain insights into the complexation mode between the fluorophore (L) and the target metal ions (Fe3+ and Ru3+), we conducted a computational study employing density functional theory (DFT). This computational analysis provided valuable information regarding the structural aspects of the complexes formed. The findings of this research open new avenues for the development of innovative dual chemo-sensors, offering exceptional selectivity and sensitivity for on-site metal ion detection applications. These advancements contribute to the broader field of chemical sensing and pave the way for the creation of highly efficient and reliable detection systems.