寡電子鐵紫質之製備、電化學及光譜性質研究

Preparation, Electrochemical and Spectral Properties of Iron N-Methyl-Pyridylethynyl Porphyrins

鄭宇翔(Yu-Hsian Cheng)

指導教授 ： 林敬堯

國立暨南國際大學/科技學院/應用化學系/碩士(2009年)

https://doi.org/10.6837/NCNU.2009.00258

摘要

我們之前已經成功的在free-base 5,15-biphenylporphine的meso位置接上一個或兩個N-methyl-2,3,4-pyridylethynyl的取代基，合成出一系列新穎無金屬寡電子紫質。現在我們進一步合成出同一系列的鐵紫質，並且對它們的光譜化學性質及電化學性質做進一步探討。
由觀測這些鐵紫質的紫外光-可見光光譜可以得知，個各取代基會使鐵紫質的吸收光譜產生強度不一的紅位移。在三種取代基中，以N-methyl-4-pyridylethynyl取代基對紫質的吸收光譜會產生最大的影響。
這些紫質在電化學研究中有明顯的還原電位變化，其中以N-methyl-2-pyridylethynyl顯現出有最強的拉電子效應。從電化學的偵測結果，我們推論Fe0的還原反應除了三價鐵還原變為二價鐵外，還包括了一個紫質大環的還原，推測為形成陰離子自由基（anion radical）；而Fe1、Fe3、Fe5則更進一步的表現出了第三個電子的還原，且這些還原都顯示出了相當高可逆性。各項測定結果顯示，在無金屬紫質中心鑲入鐵金屬後，並不會大幅度的改變取代基對於紫質的影響。

關鍵字

寡電子鐵紫質 ； 紫外光-可見光光譜 ； 電化學

並列摘要

We have previously studied a series of novel electron-deficient free-base porphyrins by attaching one or two N-methyl-2, 3, or 4-pyridylethynyl group to the meso positions of free-base 5,15-biphenyl-porphine. In this thesis, a series of iron(III) N-methyl-pyridylethynyl-5,15-biphenyl-porphines are prepared and studied. The UV-Visible spectra demonstrate significant absorption red-shifts of these iron porphyrins upon attaching the electron-withdrawing substituents, and N-methyl-4-pyridylethynyl group has the strongest influence on the porphyrin absorptions. Electrochemical studies show significant changes in the reduction potentials of these pophyrins, and N-methyl-2-pyridylethynyl group is the strongest electron-withdrawing substituent in the series. Based on the results of electrochemical, we conclude that Fe0 undergo two reduction. The first reduction is to reduce iron(III) to Iron(II), the second reduction is to reduce the porphyrin-ring to it’s anion radical. In addition, Fe1、Fe3、Fe5 undergo the third electron reduction, and these reductions all display good reversibility.

並列關鍵字

UV-Vis

參考文獻

1.J. Walter, X. Z. Song, A. S. John, J. Phys. Chem. B, 1997, 101, 1684-1699

2.K. M. Barkigia, M. D. Berber, J. Fajer, C. J. Medforth, M. W. Rener, K. M. Kadish, J. Am. Chem. Soc., 1990, 112, 8851-8857

3.L. D. Sparks, C. J. Medforth, M. S. Park, J. R. Chamberlain, M. R. Ondrias, M. O. Senge, K. M. Smith, and J. . Shelnutt, J. Am. Chem. Soc., 1993,115, 581-592

4.物理雙月刊2004年6月二十六卷三期 P.465

5.H. L. Anderson, Chem. Commun., 1999, 2323–2330