Study On Design, Synthesis And Application Of Rhodamine Fluorescence Probes For Fe³⁺

Iron, one of the most abundant and versatile transition metals, plays various and important roles in many biochemical processes, such as oxidation reaction, electron transfer and oxygen transport. There is increasing evidence that neither deficiencies nor excesses of iron can induce biologic disorders in the human body. Various analytical techniques have been used for sensitive iron determination, but several other metal ions were shown to interfere, require complicated pre-treatment procedures and necessitate the use of sophisticated instrumentation. Thus, in the last few years, fluorescent probes have been widely investigated for the selective detection of iron because of their ability to provide a simple, sensitive, selective, precise and economical method for online monitoring up to very low concentrations of target metal ions.Due to iron ion superparamagnetism, traditional iron ion fluorescent probes are fluorescence quenching. The quenching effect of iron on the excited state of organic fluorophores the design of Turn-ON fluorescent sensors for the detection of this metal ion tends to be much more challenging.Rhodamine derivatives are used extensively for designing Turn-ON fluorescent probes as the rhodamine fluorophore has excellent photophysical properties such as long wavelength absorption and emission, high fluorescence quantum yield, large extinction coefficient, and high photobleaching threshold. Therefor, We used rhodamine fluorophore to design Turn-ON fluorescence probe for Fe3 +.In this paper, two turn-on fluorescent probes based on rhodamine for Fe3+ were successfully designed, synthesized and characterized by various analytical techniques, which can be used in naked-eye detection for Fe3+ with high selectivity and sensitivity. They showed reversible signal changes towards Fe3+ when adding Na4P2O7 to the L-Fe3+ complex. Bioimaging investigations indicated that they were cell permeable and could be used to monitor intracellular Fe3+ in living cells by confocal microscopy. However, the latter had better ion selectivity than the former. The former could detect for Fe3+ in water, while the latter detected Fe3+ in MeOH/H2O(1:1, v/v). By the comprehensive comparison of various parameters, the latter was superior to the former in ion selectivity, response time and competition experiment.