Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wired up and ready to glow

13.12.2010
Linking silicon and carbon double bonds into an extended network with bulky molecules produces air-stable and photo-responsive crystals

Thirty years ago, no one believed that elements other than carbon, nitrogen, and oxygen could form double bonds at room temperature. But the discovery of ‘kinetic protection’ ligands—large, bulky molecules that trap heavy atoms into multiply-bonded arrangements—forced a textbook rewrite.

Researchers soon found that unsaturated bonds in newly synthesized substances such as disilenes, which have double silicon–silicon connections, generated chemical reactivity unlike any materials seen before.

Kohei Tamao and colleagues from the RIKEN Advanced Science Institute in Wako and Kyoto University have now discovered a way to make disilenes into thermally stable, light-emitting crystals by combining them with aromatic hydrocarbons(1). The key to their approach is a protecting ligand known as ‘Eind’ that is rigid enough to lock carbon and silicon atoms into a wire-like network.

Atoms make double bonds by sharing electrons through banana-shaped regions of space known as ‘pi orbitals’. If enough pi orbitals exist in a molecule, they can overlap and create conjugated pathways that allow for easy movement of electrons—properties that make such materials extremely responsive to light.

Incorporating disilenes into organic conjugated systems could produce enhanced photo-activity, but positioning two types of double bonds in one geometric plane for maximum pi orbital overlap is difficult. In 2007, Tamao and his team solved this problem by developing Eind ligands to protect a disilene–benzene compound(2). Eind groups have a stiff framework of three fused hydrocarbon rings that encapsulate the pi network and force it into a planar geometry by stacking perpendicular to it, which enabled the disilene–benzene product to be isolated as a fluorescent orange solid.

In their latest work, the researchers investigated the effects of extended organic pi conjugation by adding naphthalene and fluorene groups—aromatic molecules nearly twice the size of benzene rings—to an Eind-protected disilene. X-ray analysis revealed that the resulting red crystals also had planar silicon–carbon conjugation, a structure that produced intense fluorescent light emissions after ultraviolet irradiation (Fig. 1). “We were excited to see such strong solid-state emissions even at room temperature,” says Megumi Kobayashi, a co-author of the study.

Furthermore, these novel compounds showed unprecedented thermal stability, a critical requirement for future optical applications. “Usually, compounds having unsaturated silicon bonds are reactive and air-sensitive,” says Tsukasa Matsuo, another co-author, “but our red disilenes are air-stable for almost one year.” The team is currently working on improving the solubility of disilene–aromatic molecules to help develop longer and more light-sensitive double bonded materials.

The corresponding author for this highlight is based at the Functional Element-Organic Chemistry Unit, RIKEN Advanced Science Institute

Journal information

1. Kobayashi, M., Matsuo, T., Fukunaga, T., Hashizume, D., Fueno, H., Tanaka, K. & Tamao, K. Air-stable, room-temperature emissive disilenes with ð-extended aromatic groups. Journal of the American Chemical Society 132, 15162–15163 (2010).

2. Fukazawa, A., Li, Y., Yamaguchi, S., Tsuji, H. & Tamao, K. Coplanar oligo(p-phenylenedisilenylene)s based on the octaethyl-substituted s-hydrindacenyl groups. Journal of the American Chemical Society 129, 14164–14165 (2007).

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

More articles from Life Sciences:

nachricht For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>