Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Nanoblinds

Abstract:
Helical polymer with side groups that synchronously flip “on command”

Nanoblinds

October 25, 2005

Some molecules occur in two versions related to each other like mirror images; this property is called chirality. For example, helical polymers are chiral - they can be either left- or right-handed helices. The left and right versions differ in their optical properties, such as their optical activity (they twist the plane of polarized light in opposite directions). Molecules whose optical properties can be precisely controlled - and switched - are highly sought after, as they present interesting possibilities for new data storage devices, optical components, or liquid-crystal displays. American researchers have now developed a helical polymer with side groups that can be flipped back and forth synchronously, like Venetian blinds.

The research team headed by Bruce M. Novak from North Carolina State University and Prasad L. Polavarpu from Vanderbilt University produced a helical polymer from an achiral building block. The use of a chiral catalyst made it possible to link the monomers exclusively into helices twisted in the same direction. Raising the temperature or changing the solvent causes a sudden - and reversible - change in some of the polymer’s optical properties (optical activity and electronic circular dichroism); contrary to expectations, one other property (vibrational circular dichroism) remains unchanged. What is happening with this molecule? Does the direction of the helix change? The researchers have now been able to prove that isn’t the case. The backbone of the polymer remains the same. The only explanation for these initially contradictory seeming observations is the following: the polymer has side chains that stick out from the backbone at an angle, like little flat wings. All of these “wings” twist around the bond that attaches them to the backbone. In the end, they point in the opposite direction, relative to the helix, from where they started. This occurs synchronously, like a Venetian blind being flipped.

Why does raising the temperature or changing the solvent cause this flip? The two wing positions are not equivalent. Depending on the polarity of the solvent, one or the other form of the molecule is stabilized. A higher temperature stabilizes the less energetically favorable form of the molecule, a lower temperature stabilizes the more energetically favorable form.

“The coordinated, blind-like flipping of the many side groups as the result of an external stimulus,” says Novak, “ could also indicate a very interesting potential for the construction of molecular motors and nanomachines.”

####


Author: Bruce M. Novak, North Carolina State University Raleigh (USA),
www.ncsu.edu/chemistry/novak/page004.html

Title: A Thermal and Solvocontrollable Cylindrical Nanoshutter Based on a Single Screw-Sense Helical Polyguanidine

Angewandte Chemie International Edition, doi: 10.1002/anie.200501977

Contact:
Editorial office:
angewandte@wiley-vch.de

or David Greenberg (US)
dgreenbe@wiley.com

or Julia Lampam (UK)
jlampam@wiley.co.uk

Copyright © Angewandte Chemie

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Possible Futures

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

GLOBALFOUNDRIES Demonstrates Industry-Leading 112G Technology for Next-Generation Connectivity Solutions: High bandwidth, low power SerDes IP portfolio enables ‘connected intelligence’ in data centers and networking applications November 15th, 2017

Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures: Forgeries and product piracy are detrimental to society and industry -- 3-D microstructures can increase security -- KIT researchers develop innovative fluorescent 3-D stru November 15th, 2017

Molecular Machines

How to draw electricity from the bloodstream: A one-dimensional fluidic nanogenerator with a high power-conversion efficiency September 11th, 2017

First 3-D observation of nanomachines working inside cells: Researchers headed by IRB Barcelona combine genetic engineering, super-resolution microscopy and biocomputation to allow them to see in 3-D the protein machinery inside living cells January 27th, 2017

Micro-bubbles make big impact: Research team develops new ultrasound-powered actuator to develop micro robot November 25th, 2016

Scientists come up with light-driven motors to power nanorobots of the future: Researchers from Russia and Ukraine propose a nanosized motor controlled by a laser with potential applications across the natural sciences and medicine November 11th, 2016

Announcements

ICN2 researchers compute unprecedented values for spin lifetime anisotropy in graphene November 17th, 2017

Math gets real in strong, lightweight structures: Rice University researchers use 3-D printers to turn century-old theory into complex schwarzites November 16th, 2017

The stacked color sensor: True colors meet minimization November 16th, 2017

Nanometrics to Participate in the 6th Annual NYC Investor Summit 2017 November 16th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project