Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

21.02.2003


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.


NSF Science Expert: Andrew J. Lovinger, 703-292-4933, alovinge@nsf.gov
Principal Investigator: Virgil Percec, 215-573-5527, percec@sas.upenn.edu

NSF is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of nearly $5 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives about 30,000 competitive requests for funding, and makes about 10,000 new funding awards. NSF also awards over $200 million in professional and service contracts yearly.

Julie A. Smith | NSF
Further information:
http://www.nsf.gov
http://www.nsf.gov/od/lpa/
http://www.fastlane.nsf.gov/a6/A6Start.htm

More articles from Life Sciences:

nachricht Hopkins researchers ID neurotransmitter that helps cancers progress
26.04.2019 | Johns Hopkins Medicine

nachricht Trigger region found for absence epileptic seizures
25.04.2019 | RIKEN

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Unprecedented insight into two-dimensional magnets using diamond quantum sensors

For the first time, physicists at the University of Basel have succeeded in measuring the magnetic properties of atomically thin van der Waals materials on the nanoscale. They used diamond quantum sensors to determine the strength of the magnetization of individual atomic layers of the material chromium triiodide. In addition, they found a long-sought explanation for the unusual magnetic properties of the material. The journal Science has published the findings.

The use of atomically thin, two-dimensional van der Waals materials promises innovations in numerous fields in science and technology. Scientists around the...

Im Focus: Full speed ahead for SmartEEs at Automotive Interiors Expo 2019

Flexible, organic and printed electronics conquer everyday life. The forecasts for growth promise increasing markets and opportunities for the industry. In Europe, top institutions and companies are engaged in research and further development of these technologies for tomorrow's markets and applications. However, access by SMEs is difficult. The European project SmartEEs - Smart Emerging Electronics Servicing works on the establishment of a European innovation network, which supports both the access to competences as well as the support of the enterprises with the assumption of innovations and the progress up to the commercialization.

It surrounds us and almost unconsciously accompanies us through everyday life - printed electronics. It starts with smart labels or RFID tags in clothing, we...

Im Focus: Energy-saving new LED phosphor

The human eye is particularly sensitive to green, but less sensitive to blue and red. Chemists led by Hubert Huppertz at the University of Innsbruck have now developed a new red phosphor whose light is well perceived by the eye. This increases the light yield of white LEDs by around one sixth, which can significantly improve the energy efficiency of lighting systems.

Light emitting diodes or LEDs are only able to produce light of a certain colour. However, white light can be created using different colour mixing processes.

Im Focus: Quantum gas turns supersolid

Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.

Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...
All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

Hopkins researchers ID neurotransmitter that helps cancers progress

26.04.2019 | Life Sciences

Unprecedented insight into two-dimensional magnets using diamond quantum sensors

26.04.2019 | Physics and Astronomy

Liquid crystals in nanopores produce a surprisingly large negative pressure

26.04.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>