- A combined experimental and theoretical study to explore the catecholase-like activity of a hepta coordinated dinuclear Zn(II) complex
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A heptadentate N4O3 coordinating dinuclear zinc complex was synthesized and characterized by 1H NMR spectroscopy, IR spectroscopy and ESI MS spectroscopy studies. X-ray single crystal structure of the dinuclear complex revealed that both zinc atoms have pentacoordinated environment realized by the N2O2 donor set of ligand and one water molecule. The theoretical optimized structure of the dinuclear complex in solution phase was indicated a larger elongation take place in the bond distance between zinc and oxygen atom of coordinated water molecule which leads to come closer of two zinc atoms in solution phase in comparison of crystalline structure. This proximity of two zinc atoms fulfilled my aim for investigating the catalytic catecholase activity. The catecholase activity of the complex has been investigated under completely aerobic conditions in MeOH water medium at pH 8.0 against the model substrate 3,5-di-tert-butylcatechol (3,5-DTBC). Saturation kinetic studies have shown the order of conversion of substrate to product quinone. The mechanistic path of the oxidation process has been confirmed by UV–vis, CV and EPR spectral studies are made-up to be responsible for the oxidation of 3,5-DTBC. EPR experiment suggested generation of radical in the presence of 3,5-DTBC and that finding has been strengthened by cyclic voltammetric study. Thus, it proposed that the radical pathway is responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complex of redox-innocent ZnII ion. The ligand-centered radical generation has been further verified by density functional theory calculation.
- Hens, Amar
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- Development of bis(2-picolyl)amine-zinc chelates for imidazole receptors
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New phenyl and phenol bis(2-picolyl)amine (Dpa) derivatives have been synthesized in order to generate zinc chelates for imidazole anion receptors. Previously, binuclear phenolic zinc and copper chelates have shown affinity for pyrophosphate and guanidine anions, respectively. Herein we report significant imidazole affinity increasing from 2.38 × 106 to 2.90 × 107 for phenol-bridged binuclear zinc-Dpa chelates, as evidenced by dynamic and titration 1H NMR studies. Among the Dpa chelates investigated, the zinc-coordinated phenol group plays a crucial role in the mechanism of anion binding. Low-temperature 1H NMR experiments suggest a σν-symmetric geometry for the imidazole chelate. Computational DFT studies at the B3LYP level of theory imply that imidazole binding displaces the phenol bridge between the zinc ions. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Routasalo, Taina,Helaja, Juho,Kavakka, Jari,Koskinen, Ari M. P.
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experimental part
p. 3190 - 3199
(2009/04/07)
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- Development of Dpa-based imidazole zinc anion receptors
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A synthetic route for a new, phenolic Dpa-based aza ligand is presented and its chelation with zinc ions and imidazole were studied using UV/vis and mass spectrometry. A bathochromic shift of 30 nm was observed for the 2*Zn complex of the ligand in UV/vis
- Salo, Taina M.,Helaja, Juho,Koskinen, Ari M.P.
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p. 2977 - 2980
(2007/10/03)
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- Synthesis, molecular modeling, and pharmacological testing of bis- quinolinium cyclophanes: Potent, non-peptidic blockers of the apamin- sensitive Ca2+-activated K+ channel
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The synthesis and pharmacological testing of two series of novel bis- quinolinium cyclophanes as blockers of the apamin-sensitive Ca2+-activated K+ (SK(Ca)) channel are presented. In these cyclophanes the two 4- aminoquinolinium grou
- Rosa, Joaquin Campos,Galanakis, Dimitrios,Piergentili, Alessandro,Bhandari, Kalpana,Ganellin, C. Robin,Dunn, Philip M.,Jenkinson, Donald H.
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p. 420 - 431
(2007/10/03)
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