| From C. J. Pedersen's discover the fundamental of crown ethers to J. M. Lehn's proposition of supramolecular chemistry, molecular recognition, one of the most important concept, is not only the basis of molecular device information processing, but also an important way to assemble the advance structure. In recent years, people are paying close attention to the reserch of fluorescence chemical sensor which is based on molecular recognition. The optical chemosensors have played a vital role in the field of biomedicine owing to their ability to recognize specific objective molecule with the optical information being the output signal selectively. They are divided into colorimetric chemosensors and fluorescent chemosensors.In this thesis, salicylaldehyde azine(SAA),4,7,13,16-tetra-acetyl hydr-azine salicylidene-1,10-dioxo-4,7,13,16-tetraaza-18-crown-6(3-L4),4,7,13, 16-tetra acetyl hydrazine quinoline-1,10-dioxo-4,7,13,16-tetraaza-18-crown-6 (4-L4) and 4,7,13,16-tetra-coumarin-3-acyl-1,10-dioxo-4,7,13,16-tetraaza-18-crown-6(5-L2) were synthesized and characterized by melting point, ele-mental analysis and 1H-NMR spectrometry methods. By UV and fluorescence spectroscopy methods, we studied the spectral behavior of four compounds under the influence of H+in solution, at the same time we researched their selective sensibility and mechanism for metal ions. Specific contents are as follows:1. Schiff base compounds and their complexes have widely biological pharmacological activities, their activities depends on the structure of schiff bases and metal ions. In the second chapter, salicylaldehyde azine(SAA) was synthesized by hydrazine hydrate and salicylaldehyde for studying on the selectivity and sensing mechanism of schiff base chain for metal ions. We studied the structure of SAA under the influence of H+and investigated its selective sensibility for Ca2+, Mg2+, Zn2+, Cd2+, Mn2+, Ni2+, Co2+, Hg2+ and Cu2+ with spectroscopy methods. The result indicated that acidity of the solution can significantly affect SAA, the conformation of SAA was changed from the enol type to anion type with the increase of pH value, the absorption peak of enol type is between 295nm and 355nm, while the absorption peak of anion type at 408nm. We could learn that SAA has only spectral response for Cu2+ on selective experiments for metal ions, it can be used as chemical sensors for specific recognition to Cu2+2. Crown ether is an important receptor of molecular sensor structure, in order to investigate the impact on the selectivity on metal ions after the schiff base chain fragment of SAA was connected to crown ring and the sensing mechanism between armed crown ether and side arms. In the third chapter, crown ether 3-L4 was synthesized by the salicylidene schiff base chain of SAA was attached to 1,10-dioxo-4,7,13,16-tetraaza-18-crown-6. We also studied the effect of pH values on spectra of crown ether 3-L4 and selectivity on metal ions. The result showed the UV-visible spectra of crown ether 3-L4 is similar to changing regularity of SAA with reducing acidity of solution, but the position of peak shifted. The absorption peak of enol type appeared bule shift from 355nm to 322nm and the absorption peak of anion type also appeared bule shift from 408nm to 369nm. Fluorescence spectra also showed that the structure of crown ether 3-L4 was affected by pH value,fluorescence peak position of crown ether 3-L4 changed due to the pH's changing. Compared with the SAA, crown ether 3-L4 on the selectivity of metal ions has great change, it also has a special sensibility on Co2+ besides Cu2+, and this is a result which crown ring cooperative with side arm schiff base chain.3. Armed crown ethers have particular function because of the special function of side arm. Changing the fluorophore of side arm could investigate the selective difference and sensing mechanism of armed crown ether for metal ions and discover excellent sensor. For this reason crown ether 4-L4 was synthesized in the fourth chapter, we tested the change of UV and fluorescence spectra with pH value increasing and studied its selective sensibility for metal ions. The result indicated the absorption peak of UV visible spectra occurred red shift by the increasing of pH, intensity of absorption peak also has regular change, fluorescence intensity also marked the decrease. The test of metal ions on the selectivity showed it has only significant sensibility for Cu2+and Hg2+when pH=6.0, UV-visible and fluorescence spectra demonstrated the same conclusion on selectivity on metal ions.4. The changes of fluorophore and side arm can further explore the contributions and sensing mechanism of crown ring, side arm chain and photosensitive group on selectivity on metal ions. Crown ether 5-L2 was synthesized in the fifth chapter. We also studied the effect of pH values on spectra of crown ether 5-L2 and selective sensibility for alkali metals and alkaline earth metals. The result indicated that the absorption peak of crown ether 5-L2 gradually disappear at 276nm and arised a new absorption peak at 368nm while the system pH value more than 8.52 and gradually increases, moreover the peak of fluorescence spectra occurred red shift from 400nm to 500nm. The test of metal ions on the selectivity showed it has special sensibility for Mg2+... |
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