Takashi Uemura & Susumu
Kitagawa talk with ScienceWatch.com and answer a
few questions about this month's Fast Moving Front in the
field of Materials Science.
Article: Prussian blue nanoparticles protected by
Journal: J AM CHEM SOC, 125 (26): 7814-7815 JUL 2
Addresses: Kyoto Univ, Grad Sch Engn, Dept Synthet Chem
& Biol Chem, Sakyo Ku, Kyoto 6068501, Japan.
Kyoto Univ, Grad Sch Engn, Dept Synthet Chem & Biol
Chem, Sakyo Ku, Kyoto 6068501, Japan.
Why do you think your paper is highly
Coordination polymers composed of transition metal ions and bridging
ligands have shown many prominent features—such as magnetic, optical,
electrical, and porous properties, etc.—during the past decade. In
order to apply these fascinating properties to nanosize materials, the
understanding of their size effects in the nanometer-size regime is highly
Prussian blue (PB) analogs are representative of coordination polymers and
have played important roles in the field of molecular magnets. In this
paper, we showed a facile preparation method of size-changeable PB
nanoparticles, using an organic polymer as a protecting agent, and
demonstrated new size-dependent magnetic properties of PB. We believe that
our work has opened up new directions in the fields of not only inorganic
chemistry, but also that of the physical and materials sciences, which may
have resulted in the high citation rate.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
We have shown three new and important features which have attracted the
interest of many researchers. These are as follows:
1) PB nanoparticles could be easily prepared by the addition of an organic
polymer into the reaction mixture, and the size of the nanoparticles was
controllable by changing the feed ratio of the polymer.
2) Although bulk PB is not soluble in organic solvents, our PB
nanoparticles could be dissolved in many organic solvents because of their
miniaturized size and polymer protection. It was of interest that the PB
nanoparticles were remarkably stable in an organic solution without a
3) The PB nanoparticles exhibited a quite different magnetic behavior from
that of the bulk PB, and have also shown the first example of a
size-dependent magnetic property of the coordination polymers.
Would you summarize the significance of your paper
in layman's terms?
Before this work appeared, researchers focused only on the bulk properties
of coordination polymers. Therefore, no one knew of the properties of
coordination polymers characteristic of the nanometer regime. In this
paper, we have demonstrated, for the first time, nanosize properties of a
How did you become involved in this research and
were any particular problems encountered along the way?
Tremendous attention has been given to size-controlled particles consisting
of metals, metal oxides, and metal sulfides, because of their many
interesting properties which are significantly different from the
corresponding bulk materials. It is also well-known that organic polymers
show molecular-weight-dependent features such as solubility, viscosity,
conductivity, film-forming properties, and so on. Even though the
coordination polymers are named "polymer," studies on the molecular weight
(crystal size) effect had not been explored at that time and this is the
reason why we focused our attention on this area.
Where do you see your research leading in the
The concept described in this paper can be extended to produce a variety of
nanomaterials, and actually, many works on coordination polymer
nanoparticles have appeared recently. Formation of nanomaterials based on
coordination polymers would display advanced and characteristic functions,
such as flexible, porous, and chiral properties, which are different from
those observed in the conventional metal or metal-oxide systems.
Do you foresee any social or political implications
for your research?
Organic–inorganic hybrid nanocrystals are a new class of materials
that combine the flexibility of the electronic structure and the versatile
architecture of coordination systems, which will provide new
functionalities at the nanoscale. These coordination polymer nanomaterials
will be applied to sensors, memories, imaging, catalysts, drug delivery,
etc., and can open up new dimensions within the field of nanomaterials
Takashi Uemura, Ph.D.
Department of Synthetic Chemistry and Biological Chemistry
Graduate School of Engineering
Susumu Kitagawa, Ph.D.
Institute for Integrated Cell-Material Sciences