TanaseGroup/ResearchProjects

Outline

Our resrach activities span a wide range of inorganic chemistry, bioinorganic and organometallic chemistry with synthesis, characterization and application of a number of metal complexes originally prepared. At present, our interests mainly focused on new structural and functional multimetallic complexes and their composite and assembled systems. These strategies, learning from biological systems and from highly active heterogeneous catalytic systems, could lead to saving energy and saving resources by molecular science, technology, and electronics of the next generation. Namely, to our scientists in the 21st century, "green science" is an indispensable key word as well as more fundamental one "scientific curiosity".


 

Dr. T. Tanase's research group is divided into two subgroups, organometallic and bioinorganic subgroups, now three students belonging to each group. The recent research projects of each subgroup are described below.


Organometallic Subgroup

Recent Projects

Development of metal-metal bonded homo- and heterometallic transition metal clusters to explore new reactions with small organic molecules and physical properties.

Study on assembled small-size clusters to develope functional material, chemical and electronic devices.

Explanation

Metal-metal bonded small-size clusters of platinum and palladium have been of potential interest as minimal models for the surface of heterogeneous catalysts and as new homogeneous catalysts and photo- and electrochemical materials. In particular, heterometallic clusters could have potential to promote new homogeneous catalytic reactions which are not established by mononuclear centers. Their structures and properties can be modified by varying synthetic strategy and choice of organic ligands. In designing such cluster cores, one of the most significant problems is how to stabilize the cluster aggregation to resist cluster fragmentation during chemical reactions. The choice of supporting ligands such as multidentate phosphines is thus important to develop new metal assemblages.

 

 

We have systematically prepared and characterized metal-metal bonded di-, tri-, and high-nuclear platinum and palladium complexes supported by bidentate phosphine ligands and other multidentate organic ligands by utilizing chemical electrochemical procedures. Recently, the tridentate phosphine ligand, bis(diphenylphosphinomethyl)phenylphosphine (dpmp), has attracted our attention because the dpmp ligand has versatile bridging and chelating coordination behaviors for di- and trinuclear metal centers. We have developed systematic syntheses of homo- and heterotrimetallic platinum clusters through diplatinum precursors with dpmp ligands, which allow an access to a new family of metal-metal bonded clusters. Further, development of ordered assemblies of transition metal clusters with organic linkers has attracted increasing attention as new functional molecular devices and molecular scale electronics. We are now trying to prepare ordered-assembled metal-metal bonded cluster compounds in a hope to develop new chemical, and electronic devices.

metal-metal bonded linear triplatinum complex supported by dpmp ligands


Bioinorganic Subgroup

Recent Projects

Study on metal complexes with carbohydrate ligands to establish biomimetic sugar transformations by well-designed metal centers.

Study on carboxylate-bridged di- and multinuclear metal complexes as structural and functional models of non-redox active metalloproteins.

Explanation

Carbohydrates are indispensable building blocks and energy sources to living organisms and play important roles in many biological functions. Studies on interactions of carbohydrates with metal ions have became one of the most important subjects in bioinorganic field, since many sugar-metabolizing enzymes have been revealed to function with metal ions such as Mg2+, Mn2+, Co2+, and Zn2+ in the active sites. The bioinorganic chemistry with sugars, however, is largely unexplored in comparison with those with amino acids and nucleic acids, owing mainly to their multifunctionality, hygroscopic nature, complicated stereochemistry, and relatively low coordination ability to metal ions. We have studied the chemistry of transition-metal complexes with carbohydrates utilizing N-glycosidic bond formations. A number of mono-, di-, and trinuclear transition metal (Ni, Co, Mn, Cu, Zn) complexes with carbohydrates have been prepared and characterized by our grou. Further, we have established a facile C-2 epimerization of aldosed by nickel(II)-N-methylated diamines through a novel stereospecific rearrangement of sugar carbon skeleton. Now, we have focused on development of biomimic sugar tranformation reactions by well-designed di- and multinuclear metal complexes.

peroxo-bridged diniclear cobalt complex with N-glycoside ligands involving tetra-maltose domain

Recently, carboxylate-bridged dinuclear metal centers containing non-redox active ions such as Mg2+, Ca2+, Mn2+, Co2+ and Zn2+ are shown to be an important bioinorganic motif occurring at the active centers of phosphate ester-processing metalloenzymes, peptide and carbohydrate metabolizing metalloenzymes. We have systematically studied non-redox active dimetallic complexes by utilizing a bis-carboxylate ligand, m-xylylendiamine bis(Kemp's triacid imide) (H2XDK) and recently we are trying to introduce biorelevant molecules, such as phosphate esters and sugars, into the various dimetal centers in a hope of developing structural and functional models of non-redox active metalloproteins.

 

 
 
 

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1999.8 updated by TT
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