Ohio – From snowflakes to the leaves on a tree, objects
in nature are made of irregular molecules called
fractals. Scientists now have created and captured
an image of the largest man-made fractal molecule
at the nanoscale.
molecule, developed by researchers at the University
of Akron, Ohio University and Clemson University,
eventually could lead to new types of photoelectric
cells, molecular batteries and energy storage,
according to the scientists, whose study was published
online today by the journal Science .
A University of Akron research team led by Vice
President for Research George Newkome used molecular
self-assembly techniques to synthesize the molecule
in the laboratory. The molecule, bound with ions
of iron and ruthenium, forms a hexagonal gasket.
Ohio University physicists Saw-Wai Hla and Violeta
Iancu, who specialize in imaging objects at the nanoscale,
confirmed the creation of the man-made fractal. To
capture the image, the physicists sprayed the molecules
onto a piece of gold, chilled them to minus 449 degrees
Fahrenheit to keep them stable, and then viewed them
with a scanning tunneling microscope.
invisible to the naked eye – the molecules
are about one million times smaller than the colorful
hexagons shown in the Science image – the objects
are 12 nanometers wide. “That's big for a nanoscale
molecule. It's huge,” said Hla, an associate professor
of physics and astronomy.
“This man-made structure is one of the first nanoscale,
non-branched fractal molecules ever produced,” said
Newkome, who is lead author on the Science paper
and also serves as dean of the Graduate School and
the James and Vanita Oelschlager Professor of Science
and Technology at the University of Akron. “Blending
mathematics, art and science, these nanoscopic hexagonal-shaped
materials can be self-assembled and resemble a fine
bead necklace. These precise polymers — the first
example of a molecule possessing a ‘Star of David'
motif — may provide an entrée into novel new
types of photoelectric cells, molecular batteries
and energy storage.”
Fractals are irregular curves or shapes that retain
the same pattern when reduced or magnified. The molecule
in the study, for example, is composed of six rings,
which are made up of six smaller rings, and so on,
Hla explained. Snowflakes, broccoli florets or tree
bark would be just a few examples from nature.
and Iancu, a graduate student, also were able to
measure the electronic structure of the molecule,
which is useful to know for possible electronic
molecules) are unique in their own way, so you have
to find out what kind of properties they have so
we can initiate possible applications,” he said.
The study authors were George R. Newkome, Pingshan
Wang, Charles N. Moorefield, Tae Joon Cho, Prabhu
Mohapatra, Sinan Li, Seok-Ho Hwang and Judith A.
Palagallo, all from the University of Akron; Violeta
Iancu and Saw-Wai Hla of Ohio University; and Olena
Lukoyanova and Luis Echegoyen of Clemson University.
The research was supported by the National Science
Foundation, Air Force Office of Scientific Research
and the Ohio Board of Regents.
is a member of Ohio University's Nanoscale & Quantum
Phenomena Institute, Condensed Matter and Surface
Science group and Biomimetic Nanoscience and Nanotechnology
group, which is part of Ohio University's $8 million
NanoBioTechnology Initiative, one of three major
research priorities of the institution.