Design and synthesis of a rhodol isomer and its derivatives with high selectivity and sensitivity for sensing Hg2+ and F− in aqueous media

Abstract

Because of their high extinction coefficients, high quantum yields, and reasonable water solubility, xanthene dyes have played crucial roles in the field of molecular imaging as fluorescent tracers. In this work, a novel hydroxyl regioisomeric rhodol 1 has been designed and synthesized. Both absorption and fluorescence data in water revealed that the rhodol isomer 1 can generate stable optical signals in the pH range 4–10. The maximum absorbance wavelength (ca. 540 nm) of 1 meets perfectly the discrete excitation of the laser at 539 nm, and the emission maximum wavelength (ca. 590 nm) is largely red shifted compared to that of the rhodol fluorophore (ca. 540 nm). Meanwhile, the dye could be easily designed to form chemodosimeters or probes by modification of the carboxyl group or the hydroxyl group. The hydrazide derivative and the silyl ether derivative of the dye in aqueous media exhibited excellent selectivity and sensitivity toward Hg²⁺ and F⁻, respectively. Thus, the excellent optical properties and chemical properties of this dye allow it to be designed as a fluorescent tracer for biological applications.