槲黃素氧化酶活性中心之雙銅擬態化合物的合成、結構及其對3-羥基黃銅醇催化反應之研究
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2009
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為了合成槲黃素氧化酶活性中心的擬態化合物，本研究設計了一個對稱性的多牙基配子2,6-bis[(2-di(2-pyridylmethyl)aminoethoxy)]- benzoic acid (BDPABH)，並由此配子成功地合成出擬態化合物[Cu2(BDPAB)(CH3CN)(ClO4)](ClO4)2 (1) 及其鋅衍生物[Zn2(BDPAB)- (CH3CN)2](ClO4)3 (2)。兩個錯合物皆利用紅外光光譜和電灑質譜及X-光結構解析法進行鑑定。錯合物1為具有雙銅中心的分子結構，每個銅金屬中心的配位環境皆為扭曲的八面體。兩個銅離子間的距離為5.73 Å。在77 K下偵測錯合物1的電子順磁共振光譜，發現在g‖區域具有七隻分裂的精細結構線，且其平均精細偶合常數為72 G，並推測雙銅之間具有微弱的磁性交互作用。此外，錯合物1在乙腈電解質溶液中由循環伏安法顯示出有兩個擬可逆(quasireversible)的過程，分別為一個電子的氧化還原反應。錯合物1進行3-羥基黃銅醇的氧化斷裂催化反應時，會產生2-(dimethylamino)-2-phenylbenzofuran-3(2H)-one、3-(dimethylamino)-3-phenyl-3H-chromene-2,4-dione、benzoic acid及2-hydroxybenzil四種產物。當催化劑1的劑量提升至10 mol%時，反應24小時後，受質會被消耗完畢，且主要產物為benzoic acid；然而當受質濃度稀釋為1 × 10-4 M時，主要產物會變為3-(dimethylamino)-3-phenyl-3H-chromene-2,4-dione。
In order to mimic the active site of quercetine-2,3-dioxygenase, a symmetric ligand, 2,6-bis[(2-di(2-pyridylmethyl)aminoethoxy)]benzoic acid (BDPABH), was designed to synthesize a model complex, [Cu2(BDPAB)(CH3CN)(ClO4)](ClO4)2 (1), and a zinc derivative, [Zn2(BDPAB)(CH3CN)2](ClO4)3 (2). Both complexes 1 and 2 were characterized by IR and ESI-MS spectroscopies, and X-ray crystallography. The molecular structure of 1 revealed a dicopper core, in which the two copper centers were separated with a distance of 5.73 Å. Each copper center possessed a distorted octahedral geometry. The EPR spectrum of complex 1 recorded at 77 K has shown seven hyperfine lines in the g‖ region, with an average hyperfine coupling constant of 72 G. A weak magnetic exchange interaction between two copper centers of 1 was proposed. Cyclic voltammetry experiments recorded in CH3CN electrolytic solution of 1 exhibited two successive one-electron electrochemical events, which are quasireversible processes. Complex 1 can catalyze the oxidative cleavage of 3-hydroxyflavone to form 2-(dimethylamino)-2-phenylbenzofuran-3(2H)-one, 3-(dimethylamino)-3- phenyl-3H-chromene-2,4-dione, benzoic acid, and 2-hydroxybenzil. When catalyst 1 was increased to 10 mol%, the substrate was completely consumed within 24 hours, and the major product was benzoic acid. However, 3-(dimethylamino)-3-phenyl-3H-chromene-2,4-dione would become the major product as the concentration of the substrate was decreased to 1.4 × 10-4 M.
In order to mimic the active site of quercetine-2,3-dioxygenase, a symmetric ligand, 2,6-bis[(2-di(2-pyridylmethyl)aminoethoxy)]benzoic acid (BDPABH), was designed to synthesize a model complex, [Cu2(BDPAB)(CH3CN)(ClO4)](ClO4)2 (1), and a zinc derivative, [Zn2(BDPAB)(CH3CN)2](ClO4)3 (2). Both complexes 1 and 2 were characterized by IR and ESI-MS spectroscopies, and X-ray crystallography. The molecular structure of 1 revealed a dicopper core, in which the two copper centers were separated with a distance of 5.73 Å. Each copper center possessed a distorted octahedral geometry. The EPR spectrum of complex 1 recorded at 77 K has shown seven hyperfine lines in the g‖ region, with an average hyperfine coupling constant of 72 G. A weak magnetic exchange interaction between two copper centers of 1 was proposed. Cyclic voltammetry experiments recorded in CH3CN electrolytic solution of 1 exhibited two successive one-electron electrochemical events, which are quasireversible processes. Complex 1 can catalyze the oxidative cleavage of 3-hydroxyflavone to form 2-(dimethylamino)-2-phenylbenzofuran-3(2H)-one, 3-(dimethylamino)-3- phenyl-3H-chromene-2,4-dione, benzoic acid, and 2-hydroxybenzil. When catalyst 1 was increased to 10 mol%, the substrate was completely consumed within 24 hours, and the major product was benzoic acid. However, 3-(dimethylamino)-3-phenyl-3H-chromene-2,4-dione would become the major product as the concentration of the substrate was decreased to 1.4 × 10-4 M.
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槲黃素氧化酶