Anion Induced Fluorescence Quenching of Various Naphthalenediols

Fluorescence quenching of four naphthalenediols [1,5-; 1,7-; 2,7-; and 2,3- Naphthalenediols (NDs)] by inorganic anions [Cl−, Br−, SO₄ ²⁻ SO₃ ²⁻, S₂O₂ ²⁻, CO₃ ²⁻, NO₃ ⁻, and HPO₄ ²⁻] have been studied in 95% (v/v) water -ethanol mixture medium. The quenching was found to be dynamic in all systems. The plots of log k_q values with singlet transition energy (E_s) of the fluorophore and with ECTTS of the quencher are linear indicating the presence of electron transfer quenching mechanism. ΔG_TH values for charge transfer quenching have been determined for naphthalenediols.