Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hundreds of highly branched molecules unite in a giant self-assembled liquid crystal lattice

25.02.2003


A new liquid crystal lattice created by scientists at the University of Pennsylvania and University of Sheffield may be invisible to the naked eye, but it’s a giant in its own way.



Uniting hundreds of thousands of atoms, this supramolecular structure is one of the most complex ever made via self-assembly, where molecules organize themselves into larger structures. What’s more, it’s the first organic compound to assume an intricate structure previously seen only in metals such as uranium and various metal alloys.

The work is described in a paper published on the Web site of the journal Science.


"Understanding how self-assembly is controlled by molecular architecture will enable the design of increasingly complex nanostructures," said Virgil Percec, a professor of chemistry at Penn. "The achievement of a lattice of this size is a significant step towards designing new synthetic molecules which would form even larger structures, with dimensions approaching the wavelength of light."

Among self-assembled structures, bigger is better. Percec says if this lattice can attain dimensions equaling the wavelength of light the material could represent a new class of photonic crystals and a new approach to telecommunications. Such work could also yield molecular-scale electronics.

To create these large nanostructures, Percec and his colleagues started with a supersized building block: a carefully designed, well-defined and highly branched molecule referred to as a dendron. When thousands of these tree-like molecules come together, they organize themselves, unaided, into discrete microscopic spheres.

In the liquid crystal phase, each sphere consists of 12 tapered dendrons linked at their narrow end. Percec and his colleagues observed 30 of these globular structures arrange themselves into a tetragonal lattice whose repeat unit is a rectangular prism containing 255,240 atoms and measuring 169 by 169 by 88 angstroms. This repeat unit size is comparable to the crystal form of some spherical virus particles isolated from plants.

"Some of the complex structures in metal alloys have 200 atoms per lattice, and uranium has 30 atoms per unit," Percec said. "This encourages researchers to aim for equivalent self-assembled structures, and our work gives some pointers to synthetic chemists on how to design new dendrons for specific ’crystal’ structures."

Using increasingly sophisticated techniques, scientists engineer self-assembling molecules to arrange themselves into much larger, functioning objects. The field draws inspiration from nature, where proteins and cells are genetically encoded to arrange themselves into functional entities.

"We started our studies by trying to replicate the protein coat that surrounds a virus," Percec said. "We’ve designed these dendrons and other self-assembling molecules based on that model."

Self-assembly may prove useful in a wide range of fields, many involving encapsulation of materials: drug delivery, adhesives, pesticides, composites, coatings and paints, photographic and imaging media, catalysis, microfabrication and microelectronics. Percec’s group is now tweaking the structure of their dendron molecules so they might assemble into hollow spheres.


###
Percec is joined in the Science paper by co-authors Wook-Dong Cho at Penn and Goran Unger, Yongsong Liu and Xiangbing Zeng at the University of Sheffield. The research was funded by the UK Engineering and Physical Sciences Research Council and the National Science Foundation.


Steve Bradt | EurekAlert!
Further information:
http://www.upenn.edu/

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>