A multi-sensing quinazoline-derived fluorescent sensor for selective detection of Ru3+, Ir3+, Th4+, and UO22+ with environmental applications

Abstract

The chemosensor, 2-(10-hydroxybenzo [h]quinolin-9-yl) quinazolin-4(3H)-one (SP55) was successfully synthesized in a two-step synthesis reaction and confirmed through characterisation techniques like NMR spectroscopy, FT-IR, and HR-MS. For the optical experiments, the ligands were solubilized with a solvent mixture of (8:2) acetonitrile and water, whereas the cation salts were dissolved in water. The absorption studies ensure sensitivity only to Ru3+, Ir3+, Th4+, and uranyl nitrate (UO22+), compared to other cations. The absorption and emission tests indicated that the emission intensified on adding Ru³⁺, Ir³⁺, Th⁴⁺, and uranyl nitrate (UO₂²⁺) ions with blue shift and absorption also intensified but with red shift The limit of detection (LoD) was 0.44 nM for Ru³⁺, 2.35 nM for Ir³⁺, 1.64 nM for Th⁴⁺, and 1.99 nM for UO₂²⁺. The complex formation between the sensor and metals was confirmed using FT-IR, HR-MS, Job's plot, DFT, and ¹H NMR titration analyses. Furthermore, we used the SP55 chemosensor to detect Ru³⁺, Ir³⁺, Th⁴⁺, and uranyl nitrate (UO₂²⁺) in environmental water samples.