Synthesis And Evaluation Of Novel Fluorescent Probes For Metal Ions

Chapter1:Principles for designing fluorescent sensors for trace-level determination of metal ions are introduced. And the latest research progress in recent years on the development of fluorescent sensors for metal ions is reviewed.Chapter2:A new fluorionophore, which is composed of anthraquinone and a hydroxyl ethanolamine receptor, has been synthesized. Effect of metal ions on the fluorescence of the ionophore was investigated. The results show that the ionophore displays a highly selective and sensitive response of fluorescence quenching toward Fe3+in neutral buffer aqueous solution. There is a good linear relationship between the fluorescence intensity and Fe3+concentration in the range of4.0×10-5-3.0×10-4mol/L. The detection limit was3.8×10-7mol/LChapter3:A new acridine fluoroionophore containing two iminodiacetic acid ligands, Acridinyl Tetra Acid (ATA), was synthesized. The fluorescence sensing behavior of ATA toward metal ions was investigated in buffered aqueous media. The presence of Cu2+resulted in significant quenching of the fluorescence emission from ATA, while other metal ions posed little interferences, if any. The fluorescence response was concentration-dependent and can be well described by the modified Stern-Volmer equation. A good linear relationship (R2=0.9952) was observed up to3.0×106mol L-1Cu2+ions. The detection limit, calculated following the3σ IUPAC criteria, was1.24×10-7M. The presence of Cu2+induces the formation of a1:1ligand/metal complex at neutral pH.Chapter4:A simple,easy to use and selective spectrofluorimetric method for the determination of trace levels of aluminium has been developed using Alizarin Complexone(AC).Exhibiting absorption and fluorescence changes in the prescence of Al3+in EtOH-H2O solution at pH4.6,AC could be used as a colorimetric "naked eye" and fluorescent chemosensor for the detection of Al3+. In the presence of A13+,AC undergoes fluorescence quenching at487nm and shows the formation of a new red-shifted band at558nm.The intensity changes at the two emission peaks allow a rationmetric detection of Al3+in aqueous solution.A good linear relationship between the fluorescence intensity ratio(I487/I558) and the concentration of Al3+could be obtained in the range of0.8-4.0×10-5M(R2=0.9852).The detection limit was measured to be5.19X10-7M.Results obtained from UV-Vis and fluorescence titrations indicated that AC chelates to Al3+by forming a complex with a1:2molar ratio.