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| 題名: | 氟苯取代氮碳異位紫質鐵錯合物之合成、鑑定與氧化反應;Synthesis, Characterization and Oxygenation Reactions of meso-tetrakis(pentafluorophenyl)-N-confused-porphyrin Iron Complexes |
| 作者: | 許凱淳;Hsu, Kai-Chun |
| 貢獻者: | 化學學系 |
| 關鍵詞: | 鐵錯合物;氮碳異位紫質;Iron Complexes;N-confused-porphyrin |
| 日期: | 2018-07-30 |
| 上傳時間: | 2018-08-31 11:33:50 (UTC+8) |
| 出版者: | 國立中央大學 |
| 摘要: | 本研究我們以文獻上的方法合成出氟苯取代氮碳異位紫質 (NCTPFPP, 1)合成過程中合成出文獻上未記載的氟苯取代氮碳異位紫質衍生物 (NCTPFPOP, 2)，透過核磁共振 (NMR)、質譜(Mass)及紅外線吸收光譜 (FT-IR)進行鑑定，也得到(2)的單晶結構解析確認其結構。並且研究(1)和(2)在二氯甲烷 (DCM)及二甲基甲醯胺 (DMF)溶劑中造成互變異構的性質，(1)與DMF的氫鍵作用力會影響其結構，(2)與DMF的氫鍵作用力不易影響其結構。此外，當meso-位置取代基是拉電子基會使對氮碳異位紫質在紫外可見吸收光譜(UV-vis) 發生藍位移，而推電子基則是發生紅位移。對(1)和苯取代氮碳異位紫質 (NCTPP)進行電化學分析，以循環伏安法 (CV)量測其氧化還原電位。在正電位方面，(1)符合較缺電子的紫質特性有較高的氧化電位，無測得可逆的氧化還原峰。NCTPP的氧化電位較低，有兩組可逆的氧化還原峰。在負電位方面， NCTPP測得一組半可逆的氧化還原峰和一組可逆的氧化還原峰。(1)則測得二組可逆的氧化還原峰。由NCTPFPOP (2)在不同濃度的1H NMR測量所得環外NH化學位移隨濃度變化，我們確認NCTPFPOP (2)存在單體和二聚體的平衡反應，當二聚體比例愈高，環外NH與另一分子的環外O的分子間氫鍵作用力越強，1H NMR光譜上環外NH的化學位移會往down-field方向移動。
使用上述的(1)合成出氟苯取代氮碳異位紫質鐵錯合物( (HCTPFPPH)FeIIBr 1a、(HCTPFPP)FeIIIBr 1b )，透過ESI-MS、順磁1H NMR及UV-vis搭配過去的文獻鑑定(1a)和(1b)之結構。也得到(1b)的單晶結構解析確認其結構。(1a)的meso-位置取代基是拉電子基會使氮碳異位紫質鐵錯合物的UV-vis光譜發生藍位移。而(1a)和(1b)在順磁1H NMR光譜上可辨識的peak數目變少，推測pyrrole上H有部分的化學位移位在逆磁化學位移區域。(HCTPFPPH)FeIIBr (1a) 進行氧化反應的速率比(HCTPPH)FeIIBr要慢，符合先失去電子後活化C-H的推測反應機構，且失去電子為速率決定步驟。測量CV發現氮碳異位紫質鐵錯合物比起未接金屬的氮碳異位紫質有較佳的可逆的氧化還原表現，苯取代氮碳異位紫質鐵錯合物(HCTPPH)FeIIBr、(HCTPP)FeIIIBr和(HCTPPO)FeIIIBr分別有二組、一組和二組的可逆氧化還原峰。另外(HCTPPH)FeIIBr和(HCTPPO)FeIIIBr在高電位為單電子的氧化還原過程，在低電位則為雙電子的氧化還原過程。(HCTPFPPH)FeIIBr (1a)和(HCTPFPP)FeIIIBr (1b)分別觀察到有二個和四個可逆氧化還原步驟。
最後使用(HCTPP)FeIIIBr、(HCTPPO)FeIIIBr、(HCTPFPP)FeIIIBr (1b)與TPPFeIIICl的紫質鐵錯合物作為催化劑進行氧氣活化反應並用PPh3比較氧原子轉移反應活性。發現以TPPFeIIICl為催化劑與沒有金屬錯合物的blank幾乎無任何OPPh3產物產生，氮碳紫質鐵錯合物為催化劑有大量的OPPh3產生，反應速率低到高依序為(HCTPP)FeIIIBr、(HCTPPO)FeIIIBr及(HCTPFPP)FeIIIBr (1b)。表示氮碳異位紫質鐵錯合物在與氧氣反應的過程中或許經過高價數紫質鐵氧錯合物催化氧原子轉移反應，且具有拉電子基的(HCTPFPP)FeIIIBr 表現出最好的反應活性，符合我們預期缺電子的NCTPFPP鐵錯合物具有較穩定及活性較高的反應中間態，有助於成為較有效率的催化劑。
;The meso-tetrakis(pentafluorophenyl) N-confused porphyrin (NCTPFPP 1) was synthesized using literature method, and the other meso-tetrakis(pentafluorophenyl) N-confused oxo-porphyrin (NCTPFPOP 2) was firstly isolated and purified from the same reaction. Compound 2 was characterized by NMR and FT-IR spectroscopy methods, ESI-MS techinique and single-crystal X-ray diffraction determination to confirm a unique structure. Solvent-dependent tautomeric forms were studied on compounds 1 and 2. Compound 1 contains one amino NH proton and one inner C-H at an opposite site (2H form) in DMF, while compounds 2 has two amino NH and one inner C-H (3H form). The electron withdrawing and donating meso-substituents of N-confused porphyrin resulted in blue-shift and red-shift, respectively, on the UV-vis absorption spectrum. Cyclic voltammetery studies of 1 and meso-tetrakis(phenyl) N-confused porphyrin (NCTPP) were carried out to elucidate the positive shift on the redox potential for electron withdrawing meso-substituents of N-confused porphyrin. In the case of NCTPP, two reversible wave were observed on the positive side and one reversible and one half-reversible wave were oberserved on the negative side. In the case of 1, no reversible wave was observed on the positive side but two reversible wave were observed on the negative side. In addition, the NH chemical shift varied with concentration of 2 indicated the equilibrium between monmer and dimer.
The iron complexes of meso-tetrakis(pentafluorophenyl) N-confused porphyrin, (HCTPFPPH)FeIIBr (1a) and (HCTPFPP)FeIIIBr (1b), were synthesized and characterized by 1H NMR, UV-vis spectra and single-crystal X-ray diffraction technique. The electron withdrawing meso-substituents of 1a resulted in blue-shift on the Soret band and Q band of UV-vis absorption spectrum, while the iron complex of meso-tetrakis(p-methoxylcarbonylphenyl) N-confused porphyrin with electron donating meso-substituent resulted in red-shift on the Soret band and Q band of UV-vis absorption spectrum. The 1a and 2a with electron withdrawing meso-substituents have less amount of peaks found in paramagantic 1H NMR spectrum than (HCTPPH)FeIIBr and (HCTPP)FeIIIBr. The oxidation rate of 1a is slower than (HCTPPH)FeIIBr, which correspond to proposed mechanism. In the proposed mechanism, losing electron is rate determining step. Cyclic voltammetery studies were carried out for 1a, 1b, (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr. There are two, one and two reversible waves in (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr, respectively. Furthermore, (HCTPPH)FeIIBr and (HCTPP)FeIIIBr have one elcetorn transfer in high potential redox processes and two electrons transfer in low potential redox processes. Besides, there are two and four reversible redox steps in 1a and 1b.
Finally, we used (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr, 1b and TPPFeIIICl as catalysts to activate dioxygen and compared oxygen atom transfer reactive activity with triphenylphosphine (PPh3). We found almost no triphenylphosphine oxide (OPPh3) product was produced when using TPPFeIIICl as catalyst and blank without any complex. However using N-confused Iron complexes as catalysts could produce OPPh3. In increasing order of reaction rate are (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr and 1b. It means N-confused Iron complexes may undergo oxygen atom transfer reaction catalyzed by high valence FeV=O complexes intermediates during the reaction wih oxygen. In this process, 1b showed highest reactive activity with more stable and higher activity intermediate. |
| 顯示於類別: | [化學研究所] 博碩士論文
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