A pyrenyl-appended triazole-based ribose as a fluorescent sensor for Hg²⁺ ion

For the efficient detection of toxic trace metal ions, two pyrenyl-appended triazole-based d-ribose fluorescent chemosensors 6 and 7 were prepared and their fluoroionophoric properties toward transition metal ions were investigated. Chemosensors 6 and 7 exhibit highly selective recognition toward Hg²⁺ ion among a series of tested metal ions in CH₂Cl ₂/MeOH solution. The association constants of 6 and 7 are calculated to be 1.73 × 10⁵ M^-1 and 4.44 × 10⁵ M^-1, respectively. Both 6 and 7 formed complexes with the Hg ²⁺ ion at a 1:1 ligand-to-metal ratio with a detection limit of 10-15 μM Hg²⁺. Computational analysis demonstrated that the Hg ²⁺ ion occupied the coordination center of 6 with N² and N³ atoms in two triazole groups, thus separating and distorting the two parallel pyrenes away from each other.