Synthesis And Properties Characterization Of Novel Fe3+Fluorescent Probes Based On Rhodamine B

Ferrum is one of the most essential metal in biological systems and plays a crucial role in many biochemical processes, such as in carrying oxygen by heme, in many enzymatic reactions as a cofactor, and in cellular metabolism. Both its deficiency and overloading induce biological disorders in the living body. So that detection of ferric ions in vitro as well as in vivo is significant. Because of its paramagnetic nature which can lead to fluorescence quenching that uses fluorescent techniques to explore Fe3+is very difficult. Fluorescence enhancement through chelation of Fe3+with any fluorophore is a challenging task. Several groups have successfully detected Fe3+ions using different fluorescent sensors.Fluorescent sensors for ions and neutral analytes have consistently demonstrated their potential in a variety of fields. To date, various fluorophores with different excitation and emission wavelengths have been employed as signal reporters of chemosensors. As a fluorophore and chromophore probe, the rhodamine fluorochr-ome has attracted considerable interest from chemists on account of its excellent photophysical properties. Rhodamine derivatives with ring-closure spirolactam are nonfluorescent and colorless, whereas ring-opening of the corresponding spirolactam gived rise to strong fluorescence emission and a pink color,In this thesis, we designed and synthesized a few of new Rhodamine B derivatives which were characterized by NMR, ESI-MS and IR. These new compounds exhibited highly selective and sensitive recognition toward Fe3+over other metal ions. The selectivity mechanism of these fluorescent sensors for Fe3+was based on a combinational effect of proton transfer, chelation-enhanced fluorescence, and ring-opening of the spirolactam which resulted in the dramatic enhancement of both fluorescence and absorbance intensity as well as the color change of the solution. Moreover, the interaction between sensors and Fe3+was reversible, which can be verified by the introduction of AcO-ion into the system containing sensors and Fe3+. The Job’s plot and MS indicated the formation complex between these derivatives and Fe3+, and the complx patterns were also discussed.