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Synthesis, Characterization and Properties of Ternary Copper(II) Complexes Having Heterocyclic Ligand and α-Amino Acid Salicylaldiminates as Models for the Type-2 Sites in Copper Oxidases

Amini, Zahra | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42376 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Mohammadi Boghaei, Davar
  7. Abstract:
  8. Ternary copper (II) complexes having heterocyclic bases and α-amino acid salicylaldiminates
    as models for the type-2 sites in copper oxidases are of great biological importance. Considerable attention has given to mixed ligand complexes due to their antitumore, antimicrobial , inflammatpry , ascorbate oxidase (AO) and dopamine β-hydroxylase(DβH) and radio- imaging properties. With this in mind, new copper (II) complexes including amino acid Schiff base and heterocyclic bases (1,10 phenanthroline and 2, 2 biprydine ) have been synthesized, investigated and characterized by IR, UV-Vis and CHN. In the case of amino acid Schiff-base complexes, the tridentate ONO Schiff base ligand coordinates to metal ion through the phenolate oxygen, the imine nitrogen and the monodentate carboxylate oxygen. The chelate heterocyclic bases coordinate through the nitrogens of the heterocyclic ring. The IR spectra of complexes 1-6 showed a strong band 1630 cm-1 due to the vibration frequency of the imine’s ν(C=N) bond. The strong bands in the region of 1591-1577 cm-1 are attributable to ν_as(COO), while the bands between 1377 and 1366 cm-1 are related to ν_s(COO). The difference between these two frequencies ∆ν=ν_as (COO)-ν_s(COO) is considerable (196-255cm-1), which indicates the coordination of the carboxylate’s monodendate to the metal ion. The complexes showed a d-d band near 665 nm and a charge transfer band near 429 nm in methanol-H2O (4:1). The interactions between ternary copper complexes and vitamin C were investigated in two temperatures (298 and 303 K) and in a [complex]: [ascorbic acid] mole ratios of 1:10 and 1:100. The reported copper (II) complexes exhibited promising oxidase catalytic activity towards the aerobic oxidation of vitamin C. A linear correlation exists between the oxidase catalytic activity and the Lewis –acidity of central copper (II) ion created by the donating properties of the parent ligand. A probable mechanistic implication of the catalytic oxidation reaction has been discussed.
  9. Keywords:
  10. Ascorbic Acid ; Oxidation ; Ternary Copper (II)Complex ; Ascorbate Oxidase ; B-Hydroxylase

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