Dual-mode chemosensing of iron ions by new schiff bases derived from cinnamyl 5,5′-dimethyl- and diphenylhydantoins

Two novel hydantoin–cinnamic Schiff bases were synthesized and fully characterized using several analytical techniques, with the aim of evaluating their potential as smart chemosensors for heavy metal ions. Given the electron-donating characteristics of the hydantoin and cinnamic fragments, both compounds (1E,2E)-5,5′-dimethyl-3-((3-phenylallylidene)amino)imidazolidine-2,4-dione (K1) and (1E,2E)-5,5′-diphenyl-3-((−3-phenylallylidene)amino)imidazolidine-2,4-dione (K2) were examined by electrochemical and spectral (UV–Vis and fluorimetry) methods to determine their fundamental chemical behavior. Parallel studies used UV–Vis and fluorimetry to analyze the metal ions by complexation in solution. The greatest signal change was observed in the presence of Fe 3+ , with the candidate for its sensor detection with the highest sensitivity being the hydantoin cinnamyl Schiff base (K1). A mercury droplet working electrode was used to detect Fe 3+ after complexation with K1 and K2. Evidence for the formation of new complex compounds was provided by scanning in cyclic and DPP modes, and experiments were applied for Fe 3+ recognition using the organic ligands. The effectiveness of the new spectral and electrochemical methods was assessed based on how accurate, precise, and sensitive they were for detecting Fe 3+ . The establishment of two separate but useful methods—spectrofluorometric and electrochemical—for the detection of Fe 3+ using one type of organic ligand provides a clear advantage for the analysis. The dual-mode sensing capability of the new investigated Schiff base would allow flexible adaptation to different analytical platforms and sample types. This flexibility increases reliability through cross-validation and reduces the dependence on a single detection technique. • Two cinnamyl hydantoin–derived Schiff bases synthesized and structurally characterized. • Ligands show high selectivity and sensitivity towards Fe 3+ ions in aqueous solution. • Dual-mode detection achieved via fluorescence quenching and differential pulse voltammetry. • Submicromolar LODs: 2.09 μM (fluorescence) and 0.211 μM (electrochemistry). • Simple, label-free sensors applicable to environmental water monitoring.