二席夫鹼雙亞硝基鐵錯合物之鑑定及其反應性
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2013
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一氧化氮具有多種生理上的功能,可以調節免疫系統、使平滑肌細胞放鬆。雙亞硝基鐵錯合物在生物系統中被視為負責儲存和傳遞一氧化氮。利用[L1 = N,N’-(2,6-diisopropylphenyl)-2,3-dimethyl- 1,4-diaza-1,3-butadiene]配位基,可合成錯合物L1Fe(NO)2 (1)並確認結構。經由遠紅外線光譜儀偵測可得νNO = 1674, 1714 cm-1兩支吸收峰。錯合物1為深紫色,是因為Fe-NO電荷轉移(λmax = 550, 924 nm)所致。類似物L2Fe(NO)2 (2) [L2 = N,N’-(2,6-diisopropylphenyl)bis(imino)- acenaphthene]也被合成出來。由於錯合物2共軛骨架的影響造成遠紅外線吸收峰在1690, 1723 cm-1以及紫外/可見光吸收峰位移到λmax = 582, 1037 nm。錯合物1和2皆為空氣敏感物質,在−80 oC有氧氣的條件下,錯合物1及2的特徵吸收峰會逐漸減小,過程中沒有捕捉到含過氧化亞硝酸根的中間產物。因此,針對配位基進行修飾,選用2-吡啶甲醛以降低配位基的立體障礙、並增加配位基的電子密度。各種不同提供能力的配位基之雙亞硝基鐵錯合物[L3Fe(NO)2] (3), [L4Fe(NO)2] (4), [L5Fe(NO)2] (5) [L3 = 2,6-Diisopropyl-N-((pyridine-2-yl)methylene)benzenamine, L4 = N,N-dimethyl-N-(pyridine-2-ylmethylene)benzene-1,4-diamine, L5 = N-(2-pyridylmethylene)-4-fluorophenylamine]被一一合成。在氧氣存在的環境,錯合物3的紫外/可見光吸收峰的強度在−80 oC下逐漸減弱。我們推測在雙亞硝基鐵錯合物中,若配位基上的氮屬於sp2混成時,電子供給能力比配位基含sp3混成還弱,因此,在所合成的雙亞硝基鐵錯合物與氧氣的反應中,無法觀察到過氧化亞硝酸根中間體的生成。
Nitric oxide (NO) has versatile physiological functions including immune system regulation, and smooth muscle relaxation. It has been suggested that dinitrosyliron complexes (DNICs) is responsible for storage and transport of NO in biological systems. Dinitrosyliron complex, L1Fe(NO)2 (1) (L1 = N,N’-(2,6-diisopropylphenyl)-2,3-dimethyl-1,4- diaza-1,3-butadiene), was synthesized and structurally characterized. Two characteristic IR absorption bands (νNO = 1674, 1714 cm-1) were observed in the THF solution of 1. Complex 1 has intensive purple color due to the absorption of Fe-NO charge transfer transition (λmax = 550, 924 nm). An analogous, L2Fe(NO)2 (2) (L2 = N,N’-(2,6-diisopropylphenyl)bis(imino)- acenaphthene), was also synthesized. Infrared (1690, 1723 cm-1) and UV/vis absorptions (λmax = 582, 1037 nm) of 2 indicate the electronic influence of L2 from its conjugated backbone. Both 1 and 2 are air-sensitive. In the presence of O2, UV-vis absorption bands of 1 and 2 gradually diminish even below −80 oC. In the process, catch peroxynitrite intermediate was not observed. Hence, we manage to modify ligands which employing 2-pyridinecarboxaldehyde for reducing the steric hindrance and strengthening electron density of ligands. The L3Fe(NO)2 (3), L4Fe(NO)2 (4), and L5Fe(NO)2 (5) (L3 = 2,6-diisopropyl-N- ((pyridine-2-yl)methylene)benzenamine, L4 = N,N-dimethyl-N-(pyridine- 2-ylmethylene)benzene-1,4-diamine, L5 = N-(2-pyridylmethylene)-4- fluorophenylamine) containing differential electron donating ligands was synthesized. In the presence of O2, UV-vis absorption bands of 3 also diminish below −80 oC. We speculate that the prepared DNICs containing sp2 nitrogen donor ligands which possess less electron-donating ability than that of sp3 nitrogen donor ligands. Therefore, no peroxynitrite intermediate were observed in the reactions of the prepared DNICs and O2.
Nitric oxide (NO) has versatile physiological functions including immune system regulation, and smooth muscle relaxation. It has been suggested that dinitrosyliron complexes (DNICs) is responsible for storage and transport of NO in biological systems. Dinitrosyliron complex, L1Fe(NO)2 (1) (L1 = N,N’-(2,6-diisopropylphenyl)-2,3-dimethyl-1,4- diaza-1,3-butadiene), was synthesized and structurally characterized. Two characteristic IR absorption bands (νNO = 1674, 1714 cm-1) were observed in the THF solution of 1. Complex 1 has intensive purple color due to the absorption of Fe-NO charge transfer transition (λmax = 550, 924 nm). An analogous, L2Fe(NO)2 (2) (L2 = N,N’-(2,6-diisopropylphenyl)bis(imino)- acenaphthene), was also synthesized. Infrared (1690, 1723 cm-1) and UV/vis absorptions (λmax = 582, 1037 nm) of 2 indicate the electronic influence of L2 from its conjugated backbone. Both 1 and 2 are air-sensitive. In the presence of O2, UV-vis absorption bands of 1 and 2 gradually diminish even below −80 oC. In the process, catch peroxynitrite intermediate was not observed. Hence, we manage to modify ligands which employing 2-pyridinecarboxaldehyde for reducing the steric hindrance and strengthening electron density of ligands. The L3Fe(NO)2 (3), L4Fe(NO)2 (4), and L5Fe(NO)2 (5) (L3 = 2,6-diisopropyl-N- ((pyridine-2-yl)methylene)benzenamine, L4 = N,N-dimethyl-N-(pyridine- 2-ylmethylene)benzene-1,4-diamine, L5 = N-(2-pyridylmethylene)-4- fluorophenylamine) containing differential electron donating ligands was synthesized. In the presence of O2, UV-vis absorption bands of 3 also diminish below −80 oC. We speculate that the prepared DNICs containing sp2 nitrogen donor ligands which possess less electron-donating ability than that of sp3 nitrogen donor ligands. Therefore, no peroxynitrite intermediate were observed in the reactions of the prepared DNICs and O2.
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雙亞硝基鐵錯合物, 過氧化亞硝酸根陰離子, 一氧化氮, DNICs, peroxynitrite, nitric oxide