New Rhodamine B Fluorescent Molecular Probe Synthesis And Study Of Metal Ion And Anion Recognition

Rhodamine compound is one type of the xanthene dye. The rhodamine framework is an ideal mode to construct OFF-ON fluorescent chemosensors due to its particular structural property. Rhodamine derivatives with spirolactam structure are nonfluorescent, whereas ring-opening form of the spirolactam gives rise to a strong fluorescence emission. Moreover, the rhodamine fluorophore has a longer emission wavelength (over 550 nm), which is often preferred to serve as a reporting group for analyte to avoid the influence of background fluorescence (below 500 nm).In this dissertation, starting from N, N-Diethyl-3-aminophenol and o-phthalic anhydride, six rhadamine B-schiff base derivatives were designed and synthesized. Firstly, RHB was successfully synthesized through ring formation reaction, and then RHB-B was obtained in base solution. RHB-HD was synthesized through condensation reaction between RHB-B and hydrazine hydrate, and then reacted with a series of aldehydes to form six rhadamine B-schiff base derivatives:RHB-Sal, RHB-pMOSal, RHB-NSal, RHB-ThA, RHB-PyA, RHB-ImA. The structure of all rhadamine B-schiff base derivatives were characterized by the Fourier transform infrared (FT-IR) spectra, Mass spectra (MS) and proton nuclear magnetic resonance (1H NMR) in detail.The sensoring properties of Rhodamine B-schiff base derivatives for anion were firstly studied by fluorescence and UV absorption spectroscopy, and the conditions for selectively sensoring anions were investigated. The results showed that all rhadamine B-schiff base derivatives can selectively sensoring Cr2O72- except for RHB-ImA.The sensoring properties of Rhodamine B-schiff base derivatives for cation were then studied by fluorescence and UV absorption spectroscopy. The results showed that RHB-pMOSal and RHB-NSal can selectively signal Cu2+ Furthermore, the comparison experiment was conducted to compare the sensing sensitivity of RHB-Sal, RHB-pMOSal and RHB-Nsal for Cu2+. The results indicate that the introduction of electron withdrawing group into the benzene ring of salicylaldehyde favor the sensitivity for sensoring Cu2+.