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Upload organization:Kyoto University Department of Synthetic Chemistry and Biological Chemistry  Upload date:2012/08/22

Concept behind our chemistry

Susumu Kitagawa
Department of Synthetic Chemistry and Biological Chemistry
Kyoto University


Chemistry of Coordination Space

 Wellness and prosperity are due in part to advances in material and life sciences; atoms and molecules play central roles in these disciplines. A major theme in the 20th century was the syntheses of molecules composed of atoms, which led to the development of supramolecular chemistry. Consequently, supramolecular chemistry has paved the way for nanoscience. Besides the microscopic building entities in nanoscience, the spaces surrounding and partitioning atoms and molecules may be another unknown world. What types of materials or new phenomena could be realized if nanosized spaces could be composed? 
 Walls in a nanosized world, which are composed of atoms, molecules, and apportioned spaces, should considerably affect the orientation, correlation, and assembled structure of guest molecules. Hence, simply changing the wall’s shape or material may control guest molecules. When molecules are confined in a space and undergo stress due to deviations from thermodynamically and kinetically stable structures of the ambient surroundings, such stress causes an effective energy conversion and new chemical reactions. Space apportioned by atoms and molecules creates new functions based on shape and dynamics.
 At the end of the 20th century, chemists focused on supramolecular frameworks composed of molecules, while chemists in the 21st century are quickly realizing a new era of nanospace chemistry. A basic methodology for nanotechnologies is new synthetic routes to effectively build nanosized spaces on a large scale. Practical methods to realize these nanosized spaces are chemical self-assembly and self-organization where coordination bonds may be key. Coordination bonds are weaker than covalent bonds, but stronger than hydrogen bonds. The constituent organic molecules and metal ions are assembled into a variety of spatial structures under mild conditions.

  It is in this area of nanospaces (or coordination spaces) that our research interests lay.  Molecules and aggregates trapped in nanospaces have the potential to exhibit physical properties based on quantum effects. Coordination space is defined as spaces where coordination bonds play an important role in the formation of spatial structures, which exhibit various physical properties. We strive to develop chemistry to control structures and functionality of spaces, which are due to reactions of metal ions or clusters (connectors) with organic ligands (linkers) to provide coordination frameworks with infinite structures. Using a non-traditional approach where chemists, physicists, and biologists collaborate to minutely design molecules will allow new phenomena based on molecular coagulation, molecular stress, and molecular activation to be discovered (Fig. 1). Consequently, we will be able to build different sized spaces composed of several or tens of molecules. For example, in nanospaces for energy storage and transfer, we aim to control and create chemical and physical functions, including charge separations and proton transfers. 

  The mission of this field is to explore (1) new synthetic methods to precisely control nanosize spaces (nanospaces), (2) various novel Nanospace Materials, and (3) the characteristics of molecular systems in nanospaces, including magnetic, dielectric and optical properties, reactivity, and catalytic functionality. In particular, we focus on previously unknown phenomena such as molecular condensation, molecular stresses, and activation of molecules that occur in these spaces. Our laboratory emphasizes porous coordination polymers where the cavities are readily functionalized by molecular building blocks, mononuclear/polynuclear metal units, and coordination bonds as a linking force.