| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 87 === Water-soluble chromium meso-tetrakis(2,3,5,6-tetrafluoro-N-N-N-trimethyl-4-aniliniumy)porphyrin (CrIIITF4TMAP) has been synthesized. The ortho-fluoro groups in meso-substituents have provided sterical protection againet nucleophilic attack at the meso-carbon. The electron-withdrawing ability makes it more different for radical cation formation at porphine ring. The pKa1 and pKa2 for (H2O)2CrIIITF4TMAP are 7.0 and 10.0, respectively. In acidic solutions, CrIIITF4TMAP could be oxidized to form either CrIVTF4TMAP or CrVTF4TMAP by oxidants but in basic solution, only O=CrVTF4TMAP was formed. A reversible one-electron oxidation could be observed by spectroelectrochemical method, and the electronic spectra of O=CrIVTF4TMAP is obtained. O=CrVTF4TMAP could oxidize cyclopent-2-ene-1-acetic acid ( 1 ) electrocatalytically to form the corresponding enone ( 2 ) in pH 5.0 buffer solution while O=CrIVTF4TMAP could not.
A water-soluble porphyrin vanadyl meso-tetrakis(3-sulfonatomesityl)porphyrin (VOTSMP) has been synthesized. In acidic buffer solutions, a reversible one-electron oxidation could be observed by cyclic voltammetry and spectroelectrochemical method. The Soret band shifts from 424 to 420 nm and a broad band at 600 ~ 700 nm appears, indicating cation radical formation. The stable cation radical could oxidize ( 1 ) to form ( 2 ). In organic solutions, the catalytic reaction could not be observed.
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