Binol diuryl dipyrene fluorescent probe : Dual detection of silver and carbonate ions and its bioimaging applications

Binol-pyrene conjugate (BPC), as fluorescent probe was synthesized by multi-step synthetic strategies. BPC acts as a single sensor for dual analyte detection by a turn “on-off” mechanism for Ag⁺ and CO₃²⁻ ions. In the emission spectra, the monomer peaks of BPC were drastically quenched by the addition of Ag⁺ and CO₃²⁻ ions, due to the reverse photo-induced electron transfer (PET) process, excited-state deactivation via vibration and rotation of binaphthyl ring and the heavy atom effect responsible for the spin forbidden process. The probe BPC is highly selective and sensitive to Ag⁺ and CO₃²⁻ ions even in the presence of various interfering cations and anions at the physiological pH. The similar sensing strategy of BPC for Ag⁺ and CO₃²⁻ ions were further applied into the living cells, and their limit of detection (LOD) downs to 1.2 × 10^-7 M and 14 × 10^-6 M, respectively, which are close to the World Health Organization (WHO) drinking water standards. Furthermore, the binding interaction between the probe BPC with Ag⁺ and CO₃²⁻ ions and dynamic mode of quenching are evidenced by Stern-Volmer plots, quantum yields, NMR and DFT analysis.