Pyrene pyridine-conjugate as Ag selective fluorescent chemosensor

A new pyrene pyridine conjugate (PPC) has been developed as a selective fluorescent sensor for Ag⁺ ion. Probe PPC exhibits high selectivity and sensitivity toward Ag⁺ as fluorescence ‘on–off’ behaviour in HEPES-buffered DMSO–H₂O (1 : 1, (v/v) HEPES = 50 mM, pH = 7.4) solution with a detection limit of 0.29 × 10⁻⁸ M⁻¹. The turn-off fluorescence sensing of the Ag⁺ ion occurs through dual pathways, i.e. changes and alternations in the photophysical properties. The binding of Ag⁺ ion prevents excimer formation and also induces intramolecular photoinduced electron transfer (PET) from the pyridine–Ag⁺ ion bound receptor to pyrene because of structural rigidification, which quenches excimer and monomer emissions with a butterfly-like skeleton.