Abstract:

Based on Rhodamine, two novel fluorescent Hg²⁺ chemosensors(R1, R2) were synthesized from inexpensive starting materials. They were designed and synthesized with o-aminophenol and o-phenylenediamine derivatives as the Hg²⁺ chelator, the comparison between the photophysical properties of two chemosensor molecules was made. The chemosensors were designed with a photoinduced electron transfer(PET) mechanism. After binding to Hg²⁺ which blocks the PET process, the fluorescence intensity of the chemosensors was enhanced by up to 15-fold. They exhibit very strong fluorescence responses to Hg²⁺ and have remarkably higher selectivity for Hg²⁺ than for other metal ions including K⁺, Na⁺, Ca²⁺, Mg²⁺, Cd²⁺, Mn²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cu²⁺, Cr³⁺, Fe³⁺, Pb²⁺, Ag⁺, Al³⁺, Fe²⁺ and Sn²⁺ in Tris-HCl/sodium phosphate buffer. The fluorescence enhancement of R2 towards Hg²⁺ maintains stable in wide pH span(6.4―8.8) aqueous solutions.

Key words: Fluorescent chemosensor, Mercury ion, Sensor, Rhodamine fluorophore, Fluorescence intensity