Abstract: Monitoring multiple physiological parameters by using the fluorescence method requires the loading of several distinct fluorescent probes which are excitable at the same fixed wavelength with well-separated emissions.Most current fluorescent probes only have small Stoke’s shift(50-90 nm),which limits their application in detecting multiple species simultaneously.In this work,we report a molecular probe based on a new design of receptor-Fluorophore-1-Spacer-Fluorophore-2(RFSF).The RFSF probe has a large Stoke’s shift,which is complementary to the traditional probes in detecting dual species.In this molecule,the fluorophore 1 is naphthalene and the fluorophore 2 is anthracene and the molecule can be used to detect proton.In the absence of proton,when the naphthalene is excited at 280 nm,a weak emission at 420 nm from anthracene due to energy transfer is observed.The Stoke’s shift was 140 nm,which was much greater than general fluorescent sensors with a single fluorophore,such as 60 nm for aminemethylnaphthalene.When exposed to protons,the fluorescence of anthracene at 420 nm increases.The results showed suggest that a new family of fluorescent RFSF sensors can be synthesized for biologically important chemicals,including metal ions,metabolites,proteins,and different biomarkers in the future.These valuable assay systems would benefit greatly from a wider choice of fluorescence probes with the same excitation wavelength.

Key words: molecular probes, fluorescence, Stoke’s shift, RFSF, sensor