The Design, Synthesis Of Coumarin-based Dyes And Its Appilication As Optical Probe For Ions

Molecular recognition is one of three basic functions of the supermolecular systems. i.e. molecular recognition, molecular transport and chemical reaction. The key task is designing and synthesizing chemosensor, which refers to a molecular that can selectively sense and signal the presence of target matter. Transition metal cations and familiar anions play an important role in the chemical, environmental, biology, medicine sciences, so detected them by optical molecular probe has become one of the current fronts. Coumarin-based dyes known by their excellent spectroscopic properties of large molar extinctions coefficient and high fluorescence quantum yield, have wildly used in the field of molecular biology sciences, medicine sciences. In this paper, I would develop some optical probes for some transition metal cations and familiar anions in basis of previous work of predecessor and conditions of our own laboratory. These probes, which were designed bases on intramolecular charge transfer principle and used coumarin dyes as a signal reportor, have important worth in design principle and practical application. This disstertation consists of four chapters summarizad as follows:In chapter 1, a general introduction to optical molecular probes was simply presented. Emphasis was paid on developments of probes based on inramolecular charge transfer principle and coumarin-based chemosensors for transition metal cations and familiar anions. Through summurized the relative literatures, the objective of the dissertation was proposed.In chapter 2, we have developed a new approach to enhance the ratiometric uorescence response for ?uorescent chemodosimeters via manipulating intramolecular charge transfer by modulation of the electronic features of the substituents on a chemodosimeter. To prove the effect of the strategy, in this paper, compound 1 was designed and synthesized by modulation the configuration of the coumarin moiety. The spectral character and mechanism of the compound 1 as a chemodosimeter for Fe³⁺ ion was studied. The approach have been proved to be effective, which would have a wild application.In chapter 3, Coumarin pyridyl ketone was designed and synthesized as a new chromogenic probe for transition-metal ions. Remarkably, the probe showed ion discrimination by exhibiting different extents of bathochromic shifts. This ion-dependent red-shift in the visible region allows the selective detection of Cu²⁺, Ni²⁺, and Cd²⁺ by the naked eye. In this paper, the mechanism of coumarin pyridyl ketone as a optical probe for Cu²⁺, Ni²⁺, and Cd²⁺ was primarily studied, which revealed that the pyridyl ketone moiety was the metal-binding site, whereas the carbonyl group on the coumarin moiety did not participate in the metal-binding process. The coordination of a metal ion to the pyridyl ketone moiety increased its electron-withdrawing character, which led to a stronger ICT from the electron-donating diethylamino group to the metal-complexed pyridyl ketone moiety. On the basis of this binding mode, the bathochromic shift in the absorption spectra upon addition of metal ions was rationalized by ICT.In chapter 4, We have successfully designed and synthesizied a ?uorescence turn-on probe for iodide ions. As we known, it is difficulty to reach a fluorescence turn on aim by simple coordinate approch due to its heavy atom effect quench the matter's fluorescence. Made use of the results of the chapter 3 and the principle that based on the redox reaction between Cu²⁺ and iodide ions, we have devoloped probe F-L. The probe exhibited a 20-fold ?uorescence enhancement in the presence of 4 equiv. of iodide ions, which would adapt to use in the environment.