Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More bang for your bond

22.02.2010
Size-controllable bulky ligands stabilize multiple bonds of heavy elements into photoactive materials

Organic compounds containing double or triple bonds can pack a powerful punch. By sharing electrons between atoms through a process called pi conjugation, unsaturated molecules often have exceptional photonic and electronic behavior, making them essential components in state-of-the-art products such as polymer light-emitting displays.

One way to boost the usefulness of multiply bonded materials is to add heavy elements other than carbon into organic frameworks. Now, Kohei Tamao and colleagues from the RIKEN Advanced Science Institute in Wako and Kyoto University have developed a size-controllable molecular ring system that enables double bonded silicon–phosphorus units (Si=P) to be securely incorporated into pi conjugated networks1—unlocking previously unseen photo-absorption and emission activity.

Because Si=P bonds are extremely reactive, chemists typically attach them to geometrically large molecules known as bulky ligands that protect the double bonded elements. Unfortunately, most bulky ligands cause the Si=P double bond to twist, disrupting the critical pi conjugation.

Tamao and his team designed a new type of bulky molecule—the so-called ‘Rind’ ligands—to address this rotational problem. Based on a rigid, symmetric skeleton of three fused rings known as s-hydrindacene, Rind groups also contain alkyl side chains that can be tailored in length to control ligand bulkiness.

Adding Rind ligands to Si- and P-based starting materials produced molecules with highly coplanar Si=P bond with aromatic groups on Si that maintained pi conjugation in the solid state and allowed a unique room temperature fluorescence to emerge. According to Tsukasa Matsuo, a co-author of the study, the Rind ligands interlock with each other to enforce the favored planar geometry for pi conjugation.

“Rind groups can make planar arrangements out of a variety of conjugated systems,” says Matsuo. “But the electronic effect of Rind itself is small, because they are perpendicular to the conjugated electron system.”

The researchers also discovered that Rind ligands produced startling results when used to stabilize molecules containing copper atoms and organic groups2. While organocopper compounds are extremely useful in synthetic chemistry, their structures remain largely unknown because of continuous aggregation and dissociation processes in solution. By intoducing Rind ligands to copper bromide, the team isolated stable compounds containing remarkable internal architectures, such as four copper atoms arranged into a planar square.

“We were surprised when we found the beautiful structures of the organocopper materials,” says Matsuo. The four-copper framework also gave new luminescent qualities to these complexes—another reason why the researchers are continuing to explore ways to make functional materials using innovative bulky Rind ligands.

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

Journal information
1. Li, B., Matsuo, T., Hashizume, D., Fueno, H., Tanaka, K. & Tamao, K. ð-Conjugated phosphasilenes stabilized by fused-ring bulky groups. Journal of the American Chemical Society 131, 13222–13223 (2009).

2. Ito, M., Hashizume, D., Fukunaga, T., Matsuo, T. & Tamao, K. Isolated monomeric and dimeric mixed diorganocuprates based on the size-controllable bulky ‘Rind’ ligands. Journal of the American Chemical Society 131, 18024–18025 (2009).

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6177
http://www.researchsea.com

More articles from Life Sciences:

nachricht New catalyst controls activation of a carbon-hydrogen bond
21.11.2017 | Emory Health Sciences

nachricht The main switch
21.11.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>