Synthesis, Magnetic Properties, and Phosphoesterase Activity of Dinuclear Cobalt(II) Complexes

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• 作者：Lena J. Daumann ; Peter Comba ; James A. Larrabee ; Gerhard Schenk ; Robert Stranger ; German Cavigliasso ; Lawrence R. Gahan
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：February 18, 2013
• 年：2013
• 卷：52
• 期：4
• 页码：2029-2043
• 全文大小：622K
• 年卷期：v.52,no.4(February 18, 2013)
• ISSN：1520-510X

文摘

A series of dinuclear cobalt(II) complexes has been prepared and characterized to generate functional and spectroscopic models for cobalt(II) substituted phosphoesterase enzymes such as the potential bioremediator GpdQ. Reaction of ligands based on 2,2鈥?(((2-hydroxy-5-methyl-1,3-phenylene)bis(methylene))bis((pyridin-2-ylmethyl)azanediyl)))diethanol (L1) and 2,6-bis(((2-methoxyethyl)(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol (L2) with cobalt(II) salts afforded [Co₂(CO₂EtH₂L1)(CH₃COO)₂](PF₆), [Co₂(CO₂EtL2)(CH₃COO)₂](PF₆), [Co₂(CH₃L2)(CH₃COO)₂](PF₆), [Co₂(BrL2)(CH₃COO)₂](PF₆), and [Co₂(NO₂L2)(CH₃COO)₂](PF₆). Complexes of the L2 ligands contain a coordinated methyl-ether, whereas the L1 ligand contains a coordinated alcohol. The complexes were characterized using mass spectrometry, microanalysis, X-ray crystallography, UV鈥搗is鈥揘IR diffuse reflectance spectroscopy, IR absorption spectroscopy, solid state magnetic susceptibility measurements, and variable-temperature variable-field magnetic circular dichroism (VTVH MCD) spectroscopy. Susceptibility studies show that [Co₂(CO₂EtH₂L1)(CH₃COO)₂](PF₆), [Co₂(CO₂EtL2)(CH₃COO)₂](PF₆), and [Co₂(CH₃L2)(CH₃COO)₂](PF₆) are weakly antiferromagnetically coupled, whereas [Co₂(BrL2)(CH₃COO)₂](PF₆) and [Co₂(NO₂L2)(CH₃COO)₂](PF₆) are weakly ferromagnetically coupled. The susceptibility results are confirmed by the VTVH MCD studies. Density functional theory calculations revealed that magnetic exchange coupling occurs mainly through the phenolic oxygen bridge. Implications of geometry and ligand design on the magnetic exchange coupling will be discussed. Functional studies of the complexes with the substrate bis(2,4-dinitrophenyl) phosphate showed them to be active towards hydrolysis of phosphoester substrates.