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 Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH

nachricht Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>