A Novel Rhodamine-Phenolphthalein Architecture for Selective Mercury Ion Detection in Aqueous Media

In this study, the primary objective is to synthesize a novel fluorescent Rh-PP-Rh compound and explore its extensive range of photochemical behaviors. Initially, the synthesis of the novel Rh-PP-Rh was carried out for this purpose. Subsequently, UV-Vis and fluorescence spectroscopy were employed to investigate the interactions between Rh-PP-Rh and a diverse array of ions in aqueous solvent systems. Through fluorescence and UV-Vis studies, it was observed that Rh-PP-Rh demonstrated turn-on sensor properties in the presence of Hg²⁺ ions. Furthermore, the limits of detection (LOD) and association constant (K_a) values for Rh-PP-Rh/Hg²⁺ were determined as 334 nM and 9.13×10¹¹ M^-2, respectively. Additionally, the reversible studies demonstrated a switchable on/off response upon alternate addition of HgCl₂ and [Bu₄N]F to Rh-PP-Rh. These findings suggest that the probe Rh-PP-Rh also possesses specific sensor properties for F^- ions in the presence of mercury. In addition, the investigation encompassed an assessment of the visual analysis of the color alterations of Rh-PP-Rh both on filter paper and in an EtOH/H₂O solution. The findings demonstrated that Rh-PP-Rh can be successfully utilized in solutions containing mercury, as it generates significant color transformations.