Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Interfaces: Different for every molecule

19.10.2009
A novel spectroscopic technique reveals a new fundamental property of air/water interfaces

Contrary to expectations, structurally different molecules can display different solvent properties at an interface between air and water, researchers in Japan have discovered1.

Tahei Tahara and colleagues from the RIKEN Advanced Science Institute in Wako showed that polarity at this interface cannot be defined simply, because it depends on the nature of the solute molecule at the interface.

The finding could have significant consequences for chemistry at interfaces, since the polarity of a molecule’s environment affects how it reacts with other molecules. Fields such as atmospheric science, where air/water interfaces abound, will be particularly affected.

The researchers made their discovery using an interface-selective spectroscopic technique that they developed earlier2. The spectra that the technique produces are of comparable quality to those of bulk solutions, enabling previously impossible comparisons between systems.

The researchers looked at the electronic spectra of five coumarin dyes at the interface between air and water; electronic spectra are essentially a graphical representation of a molecule’s color. Coumarin dyes all share the same basic chemical structure and are used to probe the polarity of solvents because their spectra differ depending on the molecules’ environment.

Tahara and colleagues found that the spectra of all five coumarin dyes at the air/water interface resembled a cross between the bulk spectra of coumarin in polar water and non-polar hexane. This is because the dye molecules were positioned partly in the polar water and partly in the non-polar air at the interface. However, the closeness of the spectra to either the spectrum in water or in hexane changed depending on the precise structure of each coumarin dye.

Previously it was thought that, in ordinary cases, molecules experience the same polarity—the average of that of polar water and non-polar air. The spectra Tahara and colleagues measured, however, showed that even molecules having similar structures experience substantially different polarity at the air/water interface.

The researchers found that the different molecules were positioned at slightly different angles at the interface of air and water so have different sections of their structures submerged and are, consequently, in quantitatively different surroundings.

“This work showed that, even at the same air/water interface, the interaction between the solute and solvent is significantly varied,” says Tahara. This means the molecules experience different environments at the interface, similar to being in different solvents from a view point of the stabilization energy. “This fundamental understanding of molecular behavior will be very important when people consider chemical reactivity at liquid interfaces.”

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

1. Sen, S., Yamaguchi, S. & Tahara, T. Different molecules experience different polarities at the air/water interface. Angewandte Chemie International Edition 48, 6439–6442 (2009).

2. Yamaguchi, S. & Tahara, T. Precise electronic ÷(2) spectra of molecules adsorbed at an interface measured by multiplex sum frequency generation. Journal of Physical Chemistry B 108, 19079–19082 (2004).

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6068
http://www.researchsea.com

More articles from Life Sciences:

nachricht Inactivate vaccines faster and more effectively using electron beams
23.03.2017 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

nachricht Hunting pathogens at full force
22.03.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Pulverizing electronic waste is green, clean -- and cold

22.03.2017 | Materials Sciences

Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars

22.03.2017 | Physics and Astronomy

New gel-like coating beefs up the performance of lithium-sulfur batteries

22.03.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>