Featured Research

from universities, journals, and other organizations

Molecule With A Split Personality

Date:
August 3, 2007
Source:
John Wiley & Sons, Inc.
Summary:
Researchers made a porphyrin-like ring that can do something its paper analogue can't: the new molecule can switch back and forth between the one-sided Möbius topology and a "normal" two-sided state (Hückel topology) -- without breaking the ring.

If you take a strip of paper, twist one end by 180° and then stick the two ends together to form a ring, the result is called a Möbius strip, a geometric shape with only one surface and one edge.

You can prove this by making a line along the strip with a pencil: Without lifting the pencil you get back to your starting point in the end—with the whole strip marked: at each point, both sides of the strip are marked by the line.

Ring-shaped aromatic molecules can also have a topology like that of the Möbius strip, with only one side.

Polish researchers have now made a porphyrin-like ring that can do something its paper analogue can’t. As the team led by Lechosław Latos-Grażyński reports in the journal Angewandte Chemie, the new molecule can switch back and forth between the one-sided Möbius topology and a “normal” two-sided state (Hückel topology)—without breaking the ring.

An aromatic compound is a nearly planar ring (or ring system) with bonding, yet freely mobile, electron pairs from double bonds. These so called π electrons reside in a kind of “electron cloud” with a part above and a part below the plane of the ring. This is the classic Hückel topology. Even rings that are twisted into a figure eight can have this topology.

If the ring system is twisted by 180°, the result is a Möbius topology; there is no longer a difference between the upper and lower “electron cloud”. Like the pencil line on the Möbius strip made of paper, the two clouds merge together to form a single continuous surface.

The Polish researchers have now synthesized a large molecular ring, which can be classified as an expanded porphyrin analogue, which can do what the glued-together paper strip cannot: Without having to break a single bond in the figure-eight-shaped ring system, it can switch back and forth between the Hückel and Möbius topologies.

Even the figure-eight shape is retained. The trick to this molecule with a “split personality” is two aromatic six-membered rings that lie directly opposite each other in the large ring system and form the crossing point of the figure eight. These two freely spinning rings can either lie flat on top of each other, with their planes lying in parallel, or one of the rings can be twisted by 90° so that their planes lie perpendicular to each other.

In the parallel arrangement, there is a clear distinction of the upper and lower parts of the π-electron cloud, in accordance with a Hückel topology—a solution of the compound in this configuration is green in color.

The perpendicular arrangement is the Möbius arrangement and is blue in color. The rotated six-membered ring provides the twist required to unite the upper and lower electron clouds.

Which topology the molecule prefers depends on the type of solvent and the temperature.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "Molecule With A Split Personality." ScienceDaily. ScienceDaily, 3 August 2007. <www.sciencedaily.com/releases/2007/08/070802130902.htm>.
John Wiley & Sons, Inc.. (2007, August 3). Molecule With A Split Personality. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2007/08/070802130902.htm
John Wiley & Sons, Inc.. "Molecule With A Split Personality." ScienceDaily. www.sciencedaily.com/releases/2007/08/070802130902.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) — AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) — Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) — Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) — TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins