Design of an imidazole-derived chemosensor for selective recognition of Th⁴⁺ and UO₂ ²⁺ in environmental systems

The present study reports the synthesis and characterization of 2-(4,5-diphenyl-1H-imidazole-2-yl)-3-methoxyaniline (GSNH), a new imidazole-based chemosensor, confirmed by NMR and HR-MS spectra. This chemosensor exhibited emission at 400 nm, which is red-shifted to 450 nm with enhanced emission on adding Th⁴⁺ and UO₂ ²⁺ ions. Most importantly, this sensing event reverted to its initial emission with EDTA treatment, making the sensing reversible. The sensing phenomenon has been explored based on Job plot analysis, mass spectrometry studies, DFT studies, NMR titration studies, and FT-IR spectroscopy, which demonstrated a clear 1 : 1 complex formation involving methoxy oxygen and nitrogen binding with metal ions. The chemosensor has higher sensitivity with detection thresholds of 1.49 nM and 3.48 nM for Th⁴⁺ and UO₂ ²⁺ ions, respectively, and a response time of less than 1 second. Most importantly, GSNH has been able to detect Th⁴⁺ and UO₂ ²⁺ ions in spiked environmental water samples, suggesting its applicability to act as an efficient analytical tool for monitoring thorium and uranyl ions in environmental samples.