Synthesis and Property of Metal Complexes for Understanding the Function of Metalloenzyme

Metal complexes in the center of metalloenzymes show unique functions such as catalysis, electron transfers, and oxygen fixations.  The metal complexes are, in many cases, iron, copper, and molybdenum complexes that are surrounded by amino acid residues.

This reconstruction results in the readsorption property against small molecules.  The structural change also accompanies the color change, which is useful for visual monitoring of the structural changes.

Overall structure of the protein contributes on the appearances of their unique functions in creations of hydrophobic circumstances around the active sites, stereo selectivity against substrates, and control of coordination geometry of metal complexes.

We have focused on the functions caused by the polymeric structures of proteins, and synthesized the new metal complexes that mimic the active centers of metalloenzymes.  We designed and proceeded the synthesis of metal complexes by imidazole-carboxylate type bridging ligands, which have bio-relevant coordination sites.

Metalloenzyme Model

Unique porous framework  bound by bridging ligands

For example, we have isolated and characterized a new nickel complex with imidazole-4-acetate (ima). This complex shows a unique porous framework that is useful for adsorption of small molecules.  As a novel function, we have found that the channel structure is decomposed on heating to yield amorphous.  Moreover, the initial porous structure is recovered by contact with methanol vapor.

Vacuum dehydration

/100℃

MeOH

Crystal state

Amorphous state

Structural change upon heating and

recrystallization in contact with methanol

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  1. 箇条書き項目“Syntheses, characterizations, and redox behaviors of new self-assembled metal complexes with bridging ligands incorporating chalcogen sites”

~ Recent Papers ~

・ M. Miyazawa, Y. Irie, K. Kashimoto, N. Nishina, M. Kondo,* S. Yasue, K. Maeda, and F. Uchida,

     Inorg. Chem. Commun., 2009, 12, 336-339. [DOI: 10.1016/j.inoche.2009.02.014]

  1. 箇条書き項目“Interlayered Host Created by Assemblies of Monomeric Nickel Complex with Imidazole-4-acetate Chelate Ligands”


・ M. Kondo,* M. Amano, T. Iwase, M. Miyazawa, S. Yasue, K. Maeda, F. Uchida,

     Chem. Lett., 2008, 37, 992-993. [DOI: 10.1246/cl.2008.992]

  1. 箇条書き項目“Self-assembling Construction of Novel Nanoscale Heptacobalt Complex with a S-Shaped Folding”

     


・ M. Kondo,* S. Sugahara, Y. Nakamura, M. Miyazawa, S. Yasue, K. Maeda, F. Uchida, G. Sakane, H. Kawaguchi,    

     CrystEngComm., 2008, 10, 1516-1519. [DOI: 10.1039/B802854K]

  1. 箇条書き項目“Synthesis and structural determination of new multidimensional coordination polymers with 4,4’-oxybis(benzoate) building ligands: Construction of coordination polymers with heteroorganic bridges”

・ M. Kondo,* Y. Irie, M. Miyazawa, H. Kawaguchi, S. Yasue, K. Maeda, F. Uchida,

　 J. Organomet. Chem., 2007, 692, 136-141. [DOI: 10.1016/j.jorganchem.2006.07.048]

  1. 箇条書き項目“Flexible Hexagonal Tube Framework of a New Nickel Complex Assembled from Intermolecular Hydrogen Bonds”

・ M. Kondo,* T. Iwase, Y. Fuwa, T. Horiba, M. Miyazawa, T. Naito, K. Maeda, S. Yasue, F. Uchida,

　Chem. Lett., 2005 34, 410-411. [DOI: 10.1246/cl.2005.410]

  1. 箇条書き項目“Synthesis and Synthesis and Crystal Structures of Metal Complexes with 4,5-Imidazole-dicarboxylate Chelates:  Self-assembled Structures via NH···O=C Intermolecular Hydrogen Bonds”

・ E. Shimizu, M. Kondo,* Y. Fuwa, R. P. Sarker, M. Miyazawa, M. Ueno, T. Naito, K. Maeda, F. Uchida,

　 Inorg. Chem. Commun., 2004, 7, 1191-1194. [DOI: 10.1016/j.inoche.2004.09.008]

  1. 箇条書き項目“Dynamic Coordination Polymers with 4,4’-oxybis (benzoate).  Reversible Transformations of Nano- and Non-porous Coordination Frameworks Responding to Present Solvents.”

・ M. Kondo,* Y. Irie, Y. Shimizu, M. Miyazawa, H. Kawaguchi, A. Nakamura, T. Naito, K. Maeda, F. Uchida,

     Inorg. Chem., 2004, 43, 6139-6141. [DOI: 10.1021/ic0496166]

  1. 箇条書き項目“New Copper(II) Complexes Connected by NH···O=C and NH···S=C Intermolecular Hydrogen Bonds”

・ M. Kondo,* E. Shimizu, T. Horiba, K. Nabari, Y. Fuwa, K. Unoura, T. Naito, K. Maeda, F. Uchida,

　 Chem. Lett., 2003, 944-945. [DOI: 10.1246/cl.2003.944]

  1. 箇条書き項目“A new Zn(II) coordination polymer with 4-pyridylthioacetate: assemblies of homo-chiral helices with sulfide sites”

・ M. Kondo,* M. Miyazawa, Y. Irie, R. Shinagawa, T. Horiba, A. Nakamura, T. Naito, K. Maeda, S. Utsuno, F. Uchida,

     Chem. Commun., 2002, 2156-2157. [DOI: 10.1039/B205866A]