延伸共軛紫質雙金屬錯合物的合成及其電子效應對催化反應之影響

Abstract

在本篇論文中主要合成不同的雙金屬之延伸共軛紫質錯合物，並分別探討其電子效應對於烯類環氧化、硫醚氧化以及耦合反應的催化活性影響。 第一部份的研究中，合成出CoTPP-Phen-CoCl2、ZnTPP-Phen-CoCl2以及CoTPP-Phen以不同形式配位的鈷金屬紫質錯合物，進而研究配位子對於鈷金屬催化活性的影響。利用異丁醛為輔催化劑進行烯類雙鍵的氧化催化反應時，發現此三種催化劑均有好的催化活性，指出鈷金屬無論螯合在紫質中心的吡咯環上或是在外圍的雙吡啶上，皆具有催化能力並藉此得到不錯產率的環氧產物。針對硫醚類的氧化反應只有ZnTPP-PhenCoCl2才有催化能力，在此指出了硫醚的氧化需要藉由單氧的產生才能氧化硫醚成為亞碸，而鋅金屬紫質錯合物在光照情況下為一個好的製造單氧的敏化劑。 在第二部份中，合成出MgTPP-PhenPdCl2、CoTPP-Phen-PdCl2、NiTPP-Phen-PdCl2、CuTPP-Phen-PdCl2以及ZnTPP-Phen-PdCl2五種不同紫質中心金屬的鈀金屬錯合物，並進一步探討不同金屬之電子效應對於鈀金屬進行催化耦合反應的影響。對於Heck反應，五種不同雙金屬錯合物催化劑均能得到很好的催化產率，尤其以ZnTPP-Phen-PdCl2能在最短時間內達到近乎100%的產率，而沒有延伸共軛結構的PhenPdCl2其催化活性則很差。同樣探討了Suzuki-Miyaura反應，相同的趨勢也可於此耦合反應中發現。ZnTPP-Phen-PdCl2仍是反應性最佳的催化劑，PhenPdCl2反應五小時只能觀察到微量的產物生成，而大部分催化劑則沒有很大的差異出現，唯有鈷紫質鈀催化劑於Suzuki反應的活性不同於Heck反應中的表現。

The major work of this thesis involves the synthesis of a series of extended conjugation bimetallic porphyrin complexes and the study of electronic effect on catalytic activities. The target ligand (H2TPP-Phen) was prepared by extension of conjugation through coupling with 1,10-phenatroline moiety. First, H2TPP was metallated with copper ion, followed by the nitration at β-pyrrole position to give β-NO2-CuTPP in good yields. De-metallation of β-NO2-CuTPP and subsequent reduction of nitro group into amino group β-NH2-H2TPP in the presence of tin(II) chloride and HCl proceeded smoothly. Under oxygen and photo conditions, the desired diketo-porphyrin H2TPPO2 was formed by oxidation. Finally, H2TPP-Phen was established by the condensation of H2TPPO2 and diamino-1,10-phenatroline in presence of trifluoroacetic acid. The metal complexes were prepared via the complexation with the desired metal ions. Catalytic oxidations of alkene and sulfide by a series of cobalt complexes such as CoTPP-PhenCoCl2, ZnTPP-PhenCoCl2 and CoTPP-Phen were investigated. In the epoxidation, all of the three cobalt complexes showed good catalytic activities, indicating that the cobalt ions in the coordination mode either in a porphyrin moiety or in a phenatroline site remained the same activity. Surprisingly, only the ZnTPP-PhenCoCl2 could catalyze the oxidation of a sulfide to form sulfoxide. In a detailed finding, the oxidation was through the singlet oxygen, which was produced by the irradiation of visible light of ZnTPP-PhenCoCl2 in the air. In other words, the zinc porphyrin complex can act as a photosensitizer to help the generation of singlet oxygen. Furthermore, a series of palladium complexes (MgTPP-PhenPdCl2, CoTPP-PhenPdCl2, NiTPP-PhenPdCl2, CuTPP-PhenPdCl2 and ZnTPP-PhenPdCl2) were prepared by a similar manner. The catalytic behaviors of these complexes toward Heck and Suzuki-Miyaura reactions were also investigated. In the Heck reaction, these palladium complexes showed different activities. In fact, ZnTPP-PhenPdCl2 appeared to be the most active, whereas CoTPP-PhenPdCl2 illustrated to be the least active. In Suzuki-Miyaura coupling reaction, the ZnTPP-PhenPdCl2 still remained to be the most active one.