| The design and synthesis of chemical sensors based on molecular fluorescence or luminescence sensing and molecular switch, has been one of the areas of supramolecular chemistry which is on focus. The key to get excellent performance of chemical sensors is to choose the appropriate receptors, connection as well as luminous. The crown ether ring owing cavity with different sizes in the photosensitive azacrown ether compound, is the ideal selective receptor on metal ions. If the articulated photosensitive group is proper, it can produce good selectivity and sensing performance. When it is interacted with metal ions, the corresponding photophysical and photochemical signals of photosensitive group will be occurred. The sensing mechanism can be analyzed through spectrum analysis. If the connection contains certain group, it can also participate in the identification process to improve the selective recognition property of the chemical sensor molecules with metal ions.The-CH=N-group in Schiff base chain can coordinate with metal ions effectively, it also has excellent activity spectrum. Coumarin derivatives are the excellent candidate signal groups in the design of chemical sensors because of their many advantages, such as:high fluorescence quantum yield, big Stokes shift, good light stability, adjustable photophysical and photochemical properties. Therefore, the crown ether sensors with Schiff base chain or coumarin derivatives groups bonded the azacrown rings are breakthroughs in the structural design, it is expected to get some new discoveries in the aspects of their selective recognition, sensing performance and sensing mechanism.In this paper, bis(p-dimethylaminobenzaldehyde)azine(2-L1) fragment molecule, N-(p-dimethylaminobenzaldrazocarbonylmenthly)-benzoaza-15-crown-5(3-L4), coumarin-3-formatediethanolamine(4-L1) fragment molecule, N coumarin-3-formyl benzo-10-aza-15-crown-5(5-L1), four kinds of sensor compounds were synthesized and characterized by melting point,’H-NMR, elemental analysis and MS. We investigate the spectral behaviors of the four compounds under the influence of pH as well as their selective sensibility and mechanism with metal ions in the methanol-water mixed solvent by UV-vis and fluorescence spectrum methods. Specific spectral contents are as follows:1. In order to study the selective sensibility of Schiff base chain on metal ions, in the second chapter, the bis(p-dimethylaminobenzaldehyde)azine(2-L1) fragment molecule was synthesized, and investigated the spectral behaviors under the influence of pH in the mixed solvent as well as its selective sensibility on12kinds of metal ions (Li,Na+, K+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+and Cu2+) by UV-vis and fluorescence spectrum methods. The result indicated that the UV-vis spectrum of compound2-L1only behaved special selectivity to H+; however, the fluorescence spectrum of it behaved obvious recognition and sensing behavior to H+, Mn2+and Co2+. The fluorescence of compound2-L1was efficiently quenched by H+, Mn2+and Co2+. On the basis of the Stern-Volmer formula, the effects of Mn2+and Co2+on compound2-L1belongs to the dynamic quenching of fluorescence.2. In the thirth chapter, the Schiff base chain of p-dimethylaminobenzaldrazo fragment is bonded to the crown ether ring, N-(p-dimethylaminobenzaldrazo-carbonylmenthly)-benzo-aza-15-crown-5(3-L4) was synthesized, and investigated the spectral behaviors under the influence of H+with different concentrations in the mixed solvent as well as its selective sensibility on12kinds of metal ions by UV-vis and fluorescence spectrum methods. The result indicated that the UV-vis spectrum of compound3-L4only behaved special selective sensitivity to H+; however, the fluorescence spectrum of compound3-L4behaved obvious recognition and sensing to H+and Cu2+, the fluorescence of it was efficiently quenched by H+and Cu2+. On the basis of the Stern-Volmer formula, the effect of H+and Cu2+on compound3-L4also belongs to the dynamic quenching of fluorescence. Compared with the fluorescence spectra in second chapter, the introduction of crown ether ring undoubtedly improves the selectivity recognition of chemical sensor.3. In the fourth chapter, coumarin-3-formatediethanolamine(4-L1) was synthesized, and investigated the spectral behaviors under the influence of H+with different concentrations in the mixed solvent as well as its selective sensibility on12kinds of metal ions by UV-vis and fluorescence spectrum methods. The result indicated that the UV-vis spectrum of compound4-L1only behaved special recognition to H+, with no significant response to other metal ions; however, the fluorescence spectrum of it behaved special selective sensitivity to various connections of H+, the fluorescence of compound4-L1was also efficiently quenched by Cu2+. On the basis of the Stern-Volmer formula, the effect of Cu2+on compound4-L1still belongs to the dynamic quenching of fluorescence.4. In the fifth chapter, the N-coumarin-3-formylbenzo-10-aza-15-crown-5(5-L1) was synthesized, it contains4-L1fragment molecule in its structure. It was investigated the spectral behaviors under the various connections of H+in the mixed solvent as well as its selective sensibility on12kinds of metal ions by UV-vis and fluorescence spectrum methods. The result indicated that the UV-vis spectrum of compound5-L1only behaved apparent response to H+; however, the fluorescence spectrum of it behaved obvious recognition and sensing behavior to H+and Cu2+. the fluorescence of compound5-L1was efficiently quenched by Cu2+. On the basis of the Stern-Volmer formula, the effect of Cu2+on compound5-L1belongs to the dynamic quenching of fluorescence. Compared with the fluorescence spectra in fourth chapter, the introduction of crown ether ring doesn’t have a significant contribution in selective recognition.5. In this study, the fragment molecule and the corresponding crown ether are investigated by spectrum at the same time, it is helpful to investigate the role of crown ring, connection and luminnous body in selective sensibility on metal ions. |
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