Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New insights from the nano world: Direct observation of carbon monoxide binding

10.01.2011
Carbon monoxide is highly toxic since it blocks the binding site for oxygen in hemoglobin. This very principle – a porphyrin ring with a central iron or cobalt atom that the poisonous gas attaches to – can be used to implement sensors to warn against carbon monoxide. Physicists headed by Professor Johannes Barth from the Technische Universitaet Muenchen (TUM) have, in collaboration with theorists in Lyon and Barcelona, deciphered the mechanism for binding of gas molecules to iron and cobalt porphyrins. They present the unexpected phenomena they discovered in the current issue of Nature Chemistry, including the first images.

The mechanism for binding oxygen to metalloporphyrins is a vital process for oxygen-breathing organisms. Understanding how small gas molecules are chemically bound to the complexed metal centers is also important in catalysis or the implementation of chemical sensors. When investigating these binding mechanisms, scientists use porphyrin rings with a central cobalt or iron atom. They coat a copper or silver support surface with these substances.

An important characteristic of porphyrins is their conformational flexibility. Recent research has shown that each specific geometric configuration of the metalloporphyrins has a distinct influence on their functionality. In line with the current state of research, the scientists expected only a single CO molecule to bind axial to the central metallic atom. However, detailed scanning tunnel microscopy experiments by Knud Seifert revealed that, in fact, two gas molecules dock between the central metallic atom and the two opposite nitrogen atoms. Decisive is the saddle shape of the porphyrin molecules in which the gas molecules assume the position of the rider.

The significance of the saddle geometry became apparent in model calculations done by Marie-Laure Bocquet from the University of Lyon. Her analysis helped the researchers understand the novel binding mode in detail. She also showed that the shape of the molecular saddle remains practically unchanged, even after the two gas molecules bind to the porphyrin.

The porphyrins reacted very differently when the researchers replaced the carbon monoxide with stronger-binding nitrogen monoxide. As expected, this binds directly to the central atom, albeit only a single molecule fits in each porphyrin ring. This has a significant effect on the electronic structure of the carrier molecule and the characteristic saddle becomes flattened. Thus, the porphyrin reacts very differently to different kinds of gas – a result that is relevant for potential applications, like sensors.

Dr. Willi Auwaerter, one of the authors, is thrilled: "New is that we actually saw, for the first time, the mechanism on a molecular level. We even can selectively move individual gas molecules from one porphyrin to another." The team aims to explain the physical and chemical processes on surfaces and in nanostructures. Once these fundamental questions are answered they will take on new challenges: How big is the influence of the central atom? How does the binding change in planar conformations? How can such systems be utilized to implement catalyzers and sensors through controlled charge transfers?

The research was funded by the Deutsche Forschungsgemeinschaft (Excellence Cluster "Munich-Centre for Advanced Photonics" (MAP)), the TUM Institute for Advanced Study, the European Research Council (ERC Advanced Grant MolArt), as well as the Spanish Ministerio de Ciencia E Innovacion. The Leibniz Rechenzentrum of the Bayerische Akademie der Wissenschaften provided computing time. The research group of Professor Barth is member of the Catalysis Research Center (CRC) of the TUM.

Original publication:
Cis-dicarbonyl binding at cobalt and iron porphyrins with saddle-shape conformation, Knud Seufert, Marie-Laure Bocquet, Willi Auwärter, Alexander Weber-Bargioni, Joachim Reichert, Nicolás Lorente und Johannes V. Barth, Nature Chemistry, Online 9. January 2011 – DOI: 10.1038/NCHEM.956

Link: http://www.nature.com/nchem/journal/vaop/ncurrent/full/nchem.956.html

Further publications on this topic:
Discriminative Response of Surface-Confined Metalloporphyrin Molecules to Carbon and Nitrogen Monoxide, Knud Seufert, Willi Auwaerter und Johannes V. Barth, Journal of the American Chemical Society, 2010, 132, 18141–18146 – DOI: 10.1021/ja1054884

Link: http://pubs.acs.org/doi/abs/10.1021/ja1054884

Contact:
Prof. Dr. Johannes V. Barth
Technische Universitaet Muenchen
Department of Physics (E20)
James Franck Straße 1
85748 Garching, Germany
Tel: +49 89 289 12608
Fax: +49 89 289 12338
Email: jvb@ph.tum.de

Christine Kortenbruck | idw
Further information:
http://www.bio.ph.tum.de
http://www.munich-photonics.de

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

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

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>