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 A novel synthetic antibody enables conditional “protein knockdown” in vertebrates
20.08.2018 | Technische Universität Dresden

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Metamolds: Molding a mold

20.08.2018 | Information Technology

It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

20.08.2018 | Power and Electrical Engineering

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>