Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Twisted switches

24.01.2011
Helical molecules that contract reversibly when oxidized pave the way to new single-molecule electrochemical switches

The degree of twisting of natural helical structures, such as the DNA double-helix, plays an essential role in many important biological functions. Because of their twisted architecture, artificial helices can facilitate the separation and the synthesis of chiral compounds—asymmetric molecules that cannot be superimposed with their mirror image.

New, small spring-like polymer chains, or oligomers, from organic compounds called o-phenylenes have been created by Eisuke Ohta, Takanori Fukushima, Takuzo Aida and colleagues at RIKEN Advanced Science Institute in Wako [1]. These oligomers consist of benzene rings that connect to each other at a sharp angle, leading to their helical structure. The team’s oligomers can change shape and become more rigid when subjected to an electrochemical signal (Fig. 1). They could soon serve as single-molecule machines for application in molecular computers.

Many researchers have investigated molecules that alter their features such as color, luminescence and mode of aggregation when exposed to external stimuli. However, the stimuli-induced change in rigidity demonstrated by the RIKEN team is unprecedented and may open the door to new types of molecular switches.

The researchers synthesized the o-phenylene oligomers using an iterative approach, which allowed them to gradually incorporate electrochemically sensitive units to the oligomer’s backbone.

Ohta explains that while trying to generate the longest o-phenylene oligomers ever synthesized, they noticed that the oligomers possessed highly condensed electron clouds and exhibited a significant reversible difference in rigidity upon removal of one electron during oxidation reactions.

The helical configuration easily causes cyclization—the formation of non-helical structures— which makes the synthesis and investigation of open oligomer chains difficult. The researchers overcame this hurdle by replacing hydrogen atoms positioned at the extremities of the oligomers with so-called ‘nitro functional groups’. Moreover, the octamer, which consists of eight o-phenylene units, was essential for extending the helices while preventing the cyclization, providing long oligomers of up to 48 o-phenylenes.

While purifying their products, the researchers discovered that the nitro-bearing octamer underwent a ‘chiral symmetry-breaking process’, which produced crystals that contained helices with either a left- or right-handed twist. Furthermore, the helices rapidly switched handedness in solution. However, during oxidation these structures contracted, which slowed the switching process between the two chiral states, enhancing their lifetime. These long-lived states resemble 0 and 1 in binary code, making them attractive for optical memory storage.

The researchers are currently examining the chemical and physical properties of these oligomers, which remain unexplored to date. “We want to unveil these properties now,” says Ohta.

The corresponding author for this highlight is based at the Functional Soft Matter Research Group, RIKEN Advanced Science Institute.

Journal information

[1] Ohta, E., Sato, H., Ando, S., Kosaka, A., Fukushima, T., Hashizume, D., Yamasaki, M., Hasegawa, K., Muraoka, A., Ushiyama, H., Yamashita, K. & Aida, T. Redox-responsive molecular helices with highly condensed ð-clouds. Nature Chemistry 3, 68–73 (2011).

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>