| In spite of the fact that some heavy metal ions play important roles in living systems, they are very toxic and hence capable of causing serious environmental and health problems. Some heavy metal ions, such as Fe (Ⅲ), Zn (II), Cu (II) and Co (Ⅱ) are essential for the maintenance of human metabolism. However, high concentrations of these ions can lead to many adverse health effects. It is also a fact that others such as Hg (Ⅱ), Cd (Ⅱ). and Pb (Ⅱ) are among the most toxic ions known that lack any vital or beneficial effects. Accumulation of these over time in the bodies of humans and animals can lead to serious debilitating illnesses. Therefore, the development of increasingly selective and sensitive methods for the determination of heavy metal ions is currently receiving considerable attention. Rhodamines B are highly favorable because of their excellent photophysical properties, such as high extinction coefficients, excellent quantum yields, great photostability. and relatively long emission wavelengths.In this paper, three fluorescent probes based on rhodamine B were designed and synthesized to detect Fe (III). Cu (Ⅱ). and Hg (Ⅱ). The details are summarized as follow:1. Square acylated rhodamine ethylenediamine RB1was synthesized by Rhodamine ethylenediamine and square diethyl. RB1were confirmed by1H NMR, MS and elemental analysis. RB1can detect Fe3+as a fluorescent probe. At the room temperature, investigated the influence of the solvent and the solution pH value of the probe RB1distinguish Fe3+. We do spectral titration and Job experimental to know the banding mode and ligand of the detection process. The study results showed that:the probe RB1was selectively detected iron ions in95%acetonitrile/water solution at pH7.02, the probe can be applied to detection iron ions with a linear range covering from2.0×10-5mol/L to9.0×10-5mol/L and a detection limit of3.66×10-8mol/L. In addition to Cr3+, most of metal ions on the determination of Fe3+no significant interference. Upon the addition of Fe3+, the spirolactam ring of probe RB1was opened and1:1ligand-iron complex was formed, the solution significantly enhanced fluorescence intensity at λem=583.97nm and the color changed from colorless to pink. The addition an excess of EDTA led to the fading of the fluorescence and color. The Fe3+recognition processes were proven to be a revisable process.2. A novel rhodamine B derivative RB2was synthesized facilely by condensation reaction of rhodamine B hydrazide and7-hydroxy-8-formyl quinoline, which can selective recognition Cu2+. And its structure was characterized by1H NMR, MS spectra and elemental analysis. At the room temperature, investigated the influence of the solvent, the solution pH value and response time of the probe RB2distinguish Cu2+We do spectral titration and Job experimental to know the banding mode and ligand of the detection process. The study results showed that:the probe RB2was selectively detected copper ions in95%acetonitrile/water solution at pH7.02. the probe can be applied to detection iron ions with a linear range covering from5.0×10-6mol/L to4.2×10-5mol/L and a detection limit of2.31×10-8mol/L. Upon the addition of Cu2+the spirolactam ring of probe RB2was opened and1:2ligand-copper complexes were formed, the solution significantly enhanced fluorescence intensity was pink. The addition an excess of Na2S led to the fading of the fluorescence and color. The Cu2+recognition processes were proven to be a revisable process.3. Design and synthesis of sulfur rhodamine lactam fluorescent probe RB3by rhodamine B and3-(a-bromoacetyl) coumarin. which can selective recognition mercury ions. RB3was confirmed by]H NMR, MS and elemental analysis. Used to detecte the Hg2+. other metal ions are substantially not influence. At the room temperature, investigated the influence of the solvent and the solution pH value of the probe RB3distinguish Hg+. We do titration experiments and Job experimental to know banding mode and ligand of the detection process. The study results showed that: the probe RB3was detected iron ions in50%methanol/water solution at pH7.02. the probe RB3can be highly selective recognition of Hg2+and has strong anti-interference ability, with a linear range covering from1.0×10-6mol/L to2.4×10-5mol/L and a detection limit of6.66×10-9mol/L. Upon the addition of Hg2+, the spirolactam ring of probe RB3was opened and1:1ligand-mercury complex was formed, the solution significantly enhanced fluorescence intensity was pink. Reversibility experiments show that the probe RB3recognition of Hg2+processes is a revisable process. |
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