Synthesis, characterization and catalytic activity of μ-phenoxodicopper complexes with bi-Schiff bases derived from α-amino acids
2005; CSIR-NISCAIR; Volume: 44; Issue: 11 Linguagem: Inglês
ISSN
0975-0975
Autores Tópico(s)Metal-Catalyzed Oxygenation Mechanisms
ResumoSeveral di copper compl exes and re le vant dime ta l complexes have bee n sy nthesized with th e bi -Sc hiff base li gands formed by 2,6-diformyl-4- me th y lph e no l (HDFA) with g lyci ne, L-phenylalanine, L-hi stidine or hi stamine, and characteri zed by e lemental analys is, IR, UV-vis, CD, EPR, and XPS. Usin g the CU 2 complexes as models of dopamine fi- hydroxyla se ( D,B H) and peptid y lg lycin e a-hydroxylati o n monooxygena~e ( PHM), we have in vestigated th e epoxidati on of styren e with PhlO as th e monooxygen donor. The results s how th at sty rene oxide is the main product of epoxidatio n of sty rene, and that no be nzaldehyde is formed as th e by-product. Turnover numbers (TNs) of each model complex in e poxidatio n o f sty rene are 4.7, 3. L 2.S, and 2 .5 molI C Uz. fo r the complex de ri ved from g lyc in e, phenylalan ine, L-hi stidine, and hi stam ine, respec tive ly . EPR stu dy reveals th at a hyperval e nt iodine oxo int e rmediat e CuCu <--o-lPh mi g ht be formed as th e active species. ruling o ut th e poss ibility of formation of th e hypervale nt meta l-oxo species C u(III)=O in th c oxidation course. IPC Code: Int. C I 7 C07C25 1/02; C07F I lOS Copper-containing proteins and enzymes, such as he mocyanin (Hc), tyrosinase (Tyr), dopamine fJ hydroxylase (OfJH), peptidylglycine a-hydroxylation monooxygenase (PHM), and particulate methane monooxygenase (pMMO) have biological importance. For applications related to biological oxidatio ns and developing biomimetic catalysts employed in selec tive oxidation of organics, these copper-containing proteins, enzymes and the complexes mimicking them have been continuously an active and spectacu lar re search area 1-4. In the past two decades, many inge nu
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