Click-synthesized macrocyclic fluorescent sensor for dual recognition of Hg²⁺ and dichromate ions in environmental and biological systems

Since toxic analytes present in the environment pose serious threats to the health of living organisms, their detection using efficient and reliable methods is of great importance. In this study, a new macrocyclic fluorescent sensor system with excellent sensing capabilities toward oxidants and metal ions was developed. The sensor was synthesized via a click reaction between an azide-terminated Pillar[5]arene and an alkyne-functionalized Bodipy unit, leading to the formation of a macrocyclic cage structure containing five triazole rings. After comprehensive structural characterization, the sensing performance and selectivity of the fluorescent macrocycle were investigated fluorometrically against various oxidants and metal cations. The fluorescence and UV–Vis absorption studies demonstrated that the synthesized macrocyclic probe exhibits remarkable sensing ability toward the Hg²⁺ cation and the Cr₂O₇²⁻ oxidant ion through a fluorescence turn-off mechanism. The limits of detection (LOD) were determined to be 0.812 μM for Hg²⁺ and 0.115 μM for Cr₂O₇²⁻. Furthermore, similar sensing behavior was also observed in living cell imaging studies, indicating that the developed macrocyclic probe has potential applicability in biological systems as well as environmental monitoring.