Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

New method for studying molecule reactions a breakthrough in organic chemistry

11.03.2011
UCLA nanotech research mimics enzymes in directing chemical reactions

Good chemists are passive-aggressive — they manipulate molecules without actually touching them.

In a feat of manipulating substances at the nanoscale, UCLA researchers and colleagues demonstrated a method for isolating two molecules together on a substrate and controlling how those two molecules react when excited with ultraviolet light, making detailed observations both before and after the reaction.

Their research is published today in the journal Science.

"This is one step in measuring and understanding the interactions between light and molecules, which we hope will eventually lead to more efficient conversion of sunlight to electrical and other usable forms of energy," said lead study author Paul S. Weiss, a distinguished professor of chemistry and biochemistry who holds UCLA's Fred Kavli Chair in Nanosystems Sciences. "Here, we used the energy from the light to induce a chemical reaction in a way that would not happen for molecules free to move in solution; they were held in place by their attachment to a surface and by the unreactive matrix of molecules around them."

Weiss is also director of UCLA's California NanoSystems Institute (CNSI) and a professor of materials science and engineering at the UCLA Henry Samueli School of Engineering and Applied Science.

Controlling exactly how molecules combine in order to study the resulting reactions is called regioselectivity. It is important because there are a variety of ways that molecules can combine, with varying chemical products. One way to direct a reaction is to isolate molecules and to hold them together to get regioselective reactions; this is the strategy used by enzymes in many biochemical reactions.

"The specialized scanning tunneling microscope used for these studies can also measure the absorption of light and charge separation in molecules designed for solar cells," Weiss said. "This gives us a new way to optimize these molecules, in collaboration with synthetic chemists. This is what first brought us together with our collaborators at the University of Washington, led by Prof. Alex Jen."

Alex K-Y. Jen holds the Boeing-Johnson Chair at the University of Washington, where he is a professor of materials science and engineering and of chemistry. The theoretical aspects of the study were led by Kendall Houk, a UCLA professor of chemistry and biochemistry who holds the Saul Winstein Chair in Organic Chemistry. Houk is a CNSI researcher.

The study's first author, Moonhee Kim, a graduate student in Weiss' lab, managed to isolate and control the reactions of pairs of molecules by creating nanostructures tailored to allow only two molecules fit in place. The molecules used in the study are photosensitive and are used in organic solar cells; similar techniques could be used to study a wide variety of molecules. Manipulating the way molecules in organic solar cells come together may also ultimately lead to greater efficiency.

To isolate the two molecules and align them in the desired — but unnatural — way, Kim utilized a concept similar to that of toddler's toys that feature cutouts in which only certain shapes will fit.

She created a defect, or cutout, in a self-assembled monolayer, or SAM, a single layer of molecules on a flat surface — in this case, gold. The defect in the SAM was sized so that only two organic reactant molecules would fit and would only attach with the desired alignment. As a guide to attach the molecules to the SAM in the correct orientation, sulfur was attached to the bottoms of the molecules, as sulfur binds readily to gold.

"The standard procedure for this type of chemistry is to combine a bunch of molecules in solution and let them react together, but through random combinations, only 3 percent of molecules might react in this way," UCLA's Houk said. "Our method is much more targeted. Instead of doing one measurement on thousands of molecules, we are doing a range of measurements on just two molecules."

After the molecules were isolated and trapped on the substrate, they still needed to be excited with light to react. In this case, the energy was supplied by ultraviolet light, which triggered the reaction. The researchers were able to verify the proper alignment and the reaction of the molecules using the special microscope developed by Kim and Weiss.

The work was funded by the U.S. Department of Energy, the National Science Foundation, the Air Force Office of Scientific Research and the Kavli Foundation.

The California NanoSystems Institute at UCLA is an integrated research facility located at UCLA and UC Santa Barbara. Its mission is to foster interdisciplinary collaborations in nanoscience and nanotechnology; to train a new generation of scientists, educators and technology leaders; to generate partnerships with industry; and to contribute to the economic development and the social well-being of California, the United States and the world. The CNSI was established in 2000 with $100 million from the state of California. An additional $850 million of support has come from federal research grants and industry funding. CNSI members are drawn from UCLA's College of Letters and Science, the David Geffen School of Medicine, the School of Dentistry, the School of Public Health and the Henry Samueli School of Engineering and Applied Science. They are engaged in measuring, modifying and manipulating atoms and molecules — the building blocks of our world. Their work is carried out in an integrated laboratory environment. This dynamic research setting has enhanced understanding of phenomena at the nanoscale and promises to produce important discoveries in health, energy, the environment and information technology.

Mike Rodewald | EurekAlert!
Further information:
http://www.ucla.edu

More articles from Life Sciences:

nachricht More genes are active in high-performance maize
19.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht How plants see light
19.01.2018 | 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: Maschinelles Lernen im Quantenlabor

Auf dem Weg zum intelligenten Labor präsentieren Physiker der Universitäten Innsbruck und Wien ein lernfähiges Programm, das eigenständig Quantenexperimente entwirft. In ersten Versuchen hat das System selbständig experimentelle Techniken (wieder)entdeckt, die heute in modernen quantenoptischen Labors Standard sind. Dies zeigt, dass Maschinen in Zukunft auch eine kreativ unterstützende Rolle in der Forschung einnehmen könnten.

In unseren Taschen stecken Smartphones, auf den Straßen fahren intelligente Autos, Experimente im Forschungslabor aber werden immer noch ausschließlich von...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Fliegen wird smarter – Kommunikationssystem LYRA im Lufthansa FlyingLab

• Prototypen-Test im Lufthansa FlyingLab
• LYRA Connect ist eine von drei ausgewählten Innovationen
• Bessere Kommunikation zwischen Kabinencrew und Passagieren

Die Zukunft des Fliegens beginnt jetzt: Mehrere Monate haben die Finalisten des Mode- und Technologiewettbewerbs „Telekom Fashion Fusion & Lufthansa FlyingLab“...

Im Focus: Ein Atom dünn: Physiker messen erstmals mechanische Eigenschaften zweidimensionaler Materialien

Die dünnsten heute herstellbaren Materialien haben eine Dicke von einem Atom. Sie zeigen völlig neue Eigenschaften und sind zweidimensional – bisher bekannte Materialien sind dreidimensional aufgebaut. Um sie herstellen und handhaben zu können, liegen sie bislang als Film auf dreidimensionalen Materialien auf. Erstmals ist es Physikern der Universität des Saarlandes um Uwe Hartmann jetzt mit Forschern vom Leibniz-Institut für Neue Materialien gelungen, die mechanischen Eigenschaften von freitragenden Membranen atomar dünner Materialien zu charakterisieren. Die Messungen erfolgten mit dem Rastertunnelmikroskop an Graphen. Ihre Ergebnisse veröffentlichen die Forscher im Fachmagazin Nanoscale.

Zweidimensionale Materialien sind erst seit wenigen Jahren bekannt. Die Wissenschaftler André Geim und Konstantin Novoselov erhielten im Jahr 2010 den...

Im Focus: Forscher entschlüsseln zentrales Reaktionsprinzip von Metalloenzymen

Sogenannte vorverspannte Zustände beschleunigen auch photochemische Reaktionen

Was ermöglicht den schnellen Transfer von Elektronen, beispielsweise in der Photosynthese? Ein interdisziplinäres Forscherteam hat die Funktionsweise wichtiger...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Kongress Meditation und Wissenschaft

19.01.2018 | Veranstaltungen

LED Produktentwicklung – Leuchten mit aktuellem Wissen

18.01.2018 | Veranstaltungen

6. Technologie- und Anwendungsdialog am 18. Januar 2018 an der TH Wildau: „Intelligente Logistik“

18.01.2018 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Kongress Meditation und Wissenschaft

19.01.2018 | Veranstaltungsnachrichten

Maschinelles Lernen im Quantenlabor

19.01.2018 | Physik Astronomie

Warum es für Pflanzen gut sein kann auf Sex zu verzichten

19.01.2018 | Biowissenschaften Chemie