Featured Research

from universities, journals, and other organizations

New Molecular Self-Assembly Technique May Mimic How Cells Assemble Themselves

Date:
February 21, 2003
Source:
National Science Foundation
Summary:
Researchers from the University of Pennsylvania and the University of Sheffield report in the Feb. 21 issue of Science that they have created tree-like molecules that assemble themselves into precisely structured building blocks of a quarter-million atoms. Such building blocks may be precursors to designing nanostructures for molecular electronics or photonics materials, which "steer" light in the same way computer chips steer electrons.

ARLINGTON, Va. -- Researchers from the University of Pennsylvania and the University of Sheffield report in the Feb. 21 issue of Science that they have created tree-like molecules that assemble themselves into precisely structured building blocks of a quarter-million atoms. Such building blocks may be precursors to designing nanostructures for molecular electronics or photonics materials, which "steer" light in the same way computer chips steer electrons.

Virgil Percec, the P. Roy Vagelos Chair and Professor of Chemistry at the University of Pennsylvania, and his colleagues also provide chemists with pointers for designing variations of the tree-like molecules to form even larger-scale structures. The work is funded by the Engineering and Physical Sciences Research Council in the United Kingdom and the U.S. National Science Foundation, an independent federal agency that supports fundamental research in all fields of science and engineering.

"Percec and his collaborators have developed a model that may mimic what happens in cell self-assembly," said Andrew Lovinger, NSF program officer. "This is the first time where you get large-scale supramolecular structures to assemble themselves into such exceptionally large and complex structures."

The goal of photonics is to control light the way electronics control and use electrons. A working photonics crystal would have to be approximately as large as the light's wavelength -- on the order of hundreds or thousands of nanometers -- yet precisely structured to have predictable and reproducible interactions with the light. The techniques developed by Percec and colleagues may help chemists design self-assembling materials that approach photonics size.

"Photonics crystals require repeating units whose size is in the range of the wavelength of light," Percec said. "So far, we're the only ones who can design with the precision of atoms but at a nanometer scale. This sort of precision and behavior is previously unknown in organic chemistry."

The researchers start with tree-like organic molecules, called dendrons, each of which is roughly cone-shaped. Twelve of the dendrons assemble themselves into 8,500-atom spheres. Once assembled, the spheres become a "liquid crystal," a material that flows like a liquid but has some properties of a crystalline solid. Liquid crystals are commonly found in flat-panel computer screens and many other devices.

In the right conditions, liquid crystal molecules "pack" themselves into very regular, repeating patterns, called lattices. A common lattice structure resembles neatly stacked layers of golf balls in a box. However, instead of packing into common lattices, the spheres created by Percec's team arrange themselves into much more complex formations.

"We created extremely large objects that pack into the most complex lattices rather than the simplest ones that everyone expected," Percec said. "They have lattices that we haven't seen before with organic molecules. They behave like heavy atoms, with a hard core and a soft outer part, like the electron clouds surrounding metals such as uranium."

Because they are constructed from dendrons, the spheres aren't solid, but instead have a brush-like surface composed of the dendrons' "branches." The brush-like surface allows the spheres to deform slightly and fill space more like soap bubbles than like golf balls. However, the spheres are firm enough to create repetitive lattices.

In this case, the repetitive "building block," or unit cell, comprises 30 spheres -- more than 250,000 atoms -- in a rectangular volume nearly 20 nanometers by 10 nanometers. For comparison, the rhinoviruses responsible for many human colds have diameters of about 25 nanometers. The Science paper provides pointers that may allow chemists to make even larger spheres that will pack into more complex lattices that are large enough to scatter light.


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "New Molecular Self-Assembly Technique May Mimic How Cells Assemble Themselves." ScienceDaily. ScienceDaily, 21 February 2003. <www.sciencedaily.com/releases/2003/02/030221080200.htm>.
National Science Foundation. (2003, February 21). New Molecular Self-Assembly Technique May Mimic How Cells Assemble Themselves. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2003/02/030221080200.htm
National Science Foundation. "New Molecular Self-Assembly Technique May Mimic How Cells Assemble Themselves." ScienceDaily. www.sciencedaily.com/releases/2003/02/030221080200.htm (accessed April 21, 2014).

Share This



More Matter & Energy News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Why Did Nike Fire Most Of Its Nike FuelBand Team?

Why Did Nike Fire Most Of Its Nike FuelBand Team?

Newsy (Apr. 19, 2014) Nike fired most of its Digital Sport hardware team, the group behind Nike's FuelBand device. Could Apple or an overcrowded market be behind layoffs? Video provided by Newsy
Powered by NewsLook.com
Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins