| Summary: | 博士 === 國立臺灣師範大學 === 化學研究所 === 89 === Abstract
This dissertation includes two major parts. The first part mainly involves the research of the applications of 16 ring c-pivot lariat crown ethers regarding their elctrochemistry. The second part involves the research of 16 ring c-pivot lariat crown ether and their application in fluorescence.
First Part: The main donors of the 16 ring c-pivot lariat crown ethers synthesized in this research are oxygen atoms. Therefore, it is basically better to use hard metal ions that can coordinate with oxygen atoms. The
main purpose of introducing the sidearm donor is to use its sidearm, to promote the three-dimensional complexion to increase the complex ability of crown ether on metal ions. When the side arms have different functional groups, they can be used to modify the selectivity of different metal ions. From the results of previous experiments, that the sidearm lariat crown ethers 3d, 3e and 3f, composing of —CH2CH2CH=CH3,
CH2CH2OCH3 and —CH2Py, respectively, have good selectivity for silver, lead(II) and copper (II) ions, respectively. Thus, we use these three lariat crown ethers as ionophore and fabricate selective electrodes for silver (I), lead (II) and copper (II) ions, respectively. From experimental results, we understand that the selectivity and sensitivity of ion selective electrode depends not only on the Ionophore itself, but also relates to the composition of the membrane and the characteristics of the plasticizer. The membrane electrode made of lariat crown ethers 3d-PVC-NaTPB
-NOPE and 3e-PVC-NaTPB-NOPE at a ratio of 5:50:1:100 yielded a 55.4 and 28.9 mV/decade response, near Nerstain response. On the other hand, the membrane electrode made of lariat crown ether 3f-PVC-NaTPB
-NOPE at a ratio of 25:50: 1:100 yielded a 42 mV/decade response, slightly greater than Nerstain response. The main reason for the super-Nerstain slope is the complexes of 3f lariat crown ether and copper(II) ion co-exists at 1:1 and 2:1 ratio. The effective working concentrations of the 3d, 3e and 3f lariat crown ether selective electrodes for silver, lead(II) and copper(II) ions, are range from 5´10-5 to 1´10-1M, 5´10-5 to 1´10-1M and 1´10-5 to 1´10-1M, respectively. The detection limit for all membrane ion selective electrodes is 1´10-6M. All electrodes have response time of less than 30 seconds, and their reprodibilies and life time are more than three months. Potentiometric method was used to measure the complex stability constants of these lariat crown ethers with silver, lead(II) and copper(II) in methanol. For 3d lariat crown ethers with silver and 3e lariat crown ethers with lead(II), the stability constants Ks for the 1:1 is calculated as logKs = 3.11 ± 0.03 and logKs = 3.23 ± 0.11, respectively. Similarly, for the 3f lariat crown ether with copper(II) ion, the stability constants Ks for 1:2 complex is calculated as logKs=8.99, and logKs=5.75 for the 1:1 in methanol at 25℃. In addition, commercialized sodium and silver selective electrodes were used to measure the thermodynamic parameters and complex stability constant of this series of nine 16 ring c-pivot lariat crown ethers 3a-3i. Which is very important for understanding of how the metal ions complex with metal ions. From thermodynamic data we know that the complexation of sodium and silver ions are mainly controlled by their enthalpies. While their entropies are controlled by their sidearms.
Second Part: Novel new 16 c-pivot lariat crown ethers (3j-3r) containing fluorescence group were synthesized and developed as fluorescent sensors for silver and sodium ions. From the experimental results it is found that this series of lariat crown ethers enhance on the fluorescence spectra upon the addition of sodium ions. Among the series, lariat crown
3m ether has the strongest effect. On the other hand, the emission intensity reveled for this series of lariat crown ethers are quenched of silver ions. Among the series, Ag+ showed the greatest quenching effects in the excited 3p . Single crystal X-ray diffraction results reveal the oxygen atoms of the crown ether, and the oxygen atom of the bridge head carbon, participate in the coordination of sodium ion and form a six-coordination complex.
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