Synthesis And Properties Of Novel Cationic Fluorescence Probes Based On Rhodamine B

Because of the advantages of being very sensitive, “on-off” switch ability, rapid, safe and the features of sensing ions and neutral analytes, fluorescent probe has been widely used in a variety of fields. In a number of the fluorescent probe, rhodamine is widely used to detect metal ions own to low toxicity, good light stability in a wide wavelength range, high fluorescence quantum yield, etc.Typically, rhodamine derivatives are weak fluorescence intensity, whereas ring-opening of the corresponding spirolactam gives rise to strong fluorescence emission between 500 and 600 nm. In this thesis, some modifications of the rhodamine B exhibited excellent fluorescence properties. Compounds( L1-L10) were characterized by HR-MS, 1H NMR and 13 C NMR.According to the experiments about the absorption and fluorescent spectra, L1-L6 exhibited selective recognition toward Fe3+; L7 exhibited highly selective recognition toward Cu2+ over other metal ions; L8 exhibited highly selective recognition toward Hg2+ over other metal ions; L9 and L10 exhibited highly selective recognition toward Sn4+ over other metal ions. Combined with the reported references, the recognition mechanisms were speculated to be based on ring-opening of the spirolactam by ahydrolysis mechanism and chelation, which resulted in the dramatic enhancement of fluorescence intensity. These probable mechanisms were validated by 1H NMR spectra, FTIR and ESI-MS. Among these probes,L1 and L2 have a quick response to Fe3+, the recognizing event could be completed in 1 min; ratiometric chemosensor L8 has a quick response to Hg2+, the recognizing event could be completed in 3 min; L9 has a quick response to Sn4+. Sensor L2, L7, L8 and L9 could be applied in living cells, and the experimental results demonstrated that they had potential applications in biological systems.