Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Precision molecular assembly

A finely tuned rare-earth metal catalyzes the exact interactions needed for site-selective molecular synthesis

Subtle electronic differences between metals in the periodic table can lead to radical changes in chemical reactivity. Now, a research team led by Zhaomin Hou from the RIKEN Advanced Science Institute, Wako, has found that scandium, a seldom-studied rare-earth metal, enables the catalytic addition of functional groups to unsaturated carbon bonds with better selectivity than other metals1—a boon to chemists seeking precise control over molecular assembly.

Hou and his team are experts in the field of rare-earth materials, and recently discovered that a so-called ‘half-sandwich’ complex, comprising a scandium cation and a pentagonal carbon ring, could efficiently catalyze production of long polymer chains.

“Our scandium complex acted as an excellent catalyst for olefin polymerization, with unprecedented activity and selectivity,” says Hou. Because the scandium complex targeted unsaturated carbon bonds during the polymerization process, the researchers realized its enormous potential in other important synthetic reactions, such as carbometalation.

During carbometalation, a metal catalyst helps an organic unit, such as a methyl group, and a metal—commonly aluminum—to add to a carbon–carbon double or triple bond. Researchers can then replace the metal with another molecular group, making carbometalation an effective way to construct carbon-based frameworks containing multiple, branched functional units.

What is difficult, though, is controlling the regioselectivity of the catalytic addition—the precise positions where the organic and metal units add to the unsaturated carbon bonds. When the team first attempted carbometalation with the scandium catalyst and a typical triple-bonded carbon molecule, it achieved only moderate regioselectivity, similar to other transition metal catalysts.

However, when the researchers tethered a silyl ether—a group containing silicon, oxygen, and hydrocarbon atoms—to the end of the triple-bonded carbon substrate, the carbometalation proceeded with extremely high regioselectivity; over 99% of the final product was isolated as a single chemical isomer. Further experiments revealed that the combination of a silyl ether tether group and a scandium-based catalyst enabled controllable carbometalation on numerous unsaturated organic molecules—in many cases, with higher regioselectivity than any other catalyst.

According to Hou, the unprecedented selectivity achievable through this method is due to a balanced interaction between the oxygen atom of the silyl ether adduct and the scandium cation. “This interaction should not be too strong,” he says, “otherwise coordination and insertion processes around unsaturated carbon–carbon triple and double bonds would be hampered.”

The researchers are currently exploring new ways to utilize rare-earth complexes for chemical transformations involving carbon and other elemental bonds.

The corresponding author for this highlight is based at the Organometallic Chemistry Laboratory, RIKEN Advanced Science Institute

Saeko Okada | Research asia research news
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>