Nav: Home

Synthesis of helical ladder polymers

May 20, 2019

Ladder polymers -- molecules made of adjacent rings sharing two or more atoms -- are challenging to synthesize, because they require highly selective, quantitative reactions to avoid the formation of branching structures or of interruptions in the ring sequence in the polymer chain. Moreover, most existing strategies for the synthesis of ladder polymers suffer from severe limitations in terms of selectivity and quantitativity. Another important type of molecules are molecules with a helical structure (such as DNA and proteins), which play an important role in molecular recognition and catalysis. Thus, the fabrication of molecules that possess both a ladder and a helical structure could open up new applications of polymeric materials.

Tomoyuki Ikai, Timothy M. Swager and colleagues from an international collaboration started from triptycene, an aromatic hydrocarbon that is an achiral molecule, but from which chiral derivatives can be obtained by introducing substituents in the benzene rings in an asymmetric manner. Optically active triptycenes have practical uses as chiral materials, for example for chiral separation and circularly polarized luminescent materials. The researchers then used the chiral triptycenes as a framework to efficiently form single-handed helical ladder polymers using electrophilic aromatic substitution. Steric repulsion in the system resulted in the formation of one-handed twisted ladder units. The reactions were quantitative and regioselective (that is, there is a preferred direction of chemical bonding), which enabled the synthesis of optically active ladder polymers with well-defined helical geometry. No byproducts were detected.

Several techniques, including spectroscopy and microscopy techniques, were used to characterize the reaction products during synthesis, and molecular dynamics simulations were employed to understand the structure of the resulting molecules, confirming the right-handed helical ladder geometry. The researchers also measured the optical activity of the molecules.

The newly reported synthesis route will open up the synthesis of nanoscale helical ladder architectures and optically active chiral materials. "We believe that these ladder polymers, which can fall into a new category of helical polymers, represent a promising class of advanced materials for use as nanochannels for molecular/ion transport, organic electronics, specific reaction fields, and functional hosts through further modification of the backbone and pendant units," commented the authors in the paper.
-end-


Kanazawa University

Related Molecules Articles:

How molecules self-assemble into superstructures
Most technical functional units are built bit by bit according to a well-designed construction plan.
Breaking down stubborn molecules
Seawater is more than just saltwater. The ocean is a veritable soup of chemicals.
Shaping the rings of molecules
Canadian chemists discover a natural process to control the shape of 'macrocycles,' molecules of large rings of atoms, for use in pharmaceuticals and electronics.
The mysterious movement of water molecules
Water is all around us and essential for life. Nevertheless, research into its behaviour at the atomic level -- above all how it interacts with surfaces -- is thin on the ground.
Spectroscopy: A fine sense for molecules
Scientists at the Laboratory for Attosecond Physics have developed a unique laser technology for the analysis of the molecular composition of biological samples.
Looking at the good vibes of molecules
Label-free dynamic detection of biomolecules is a major challenge in live-cell microscopy.
Colliding molecules and antiparticles
A study by Marcos Barp and Felipe Arretche from Brazil published in EPJ D shows a model of the interaction between positrons and simple molecules that is in good agreement with experimental results.
Discovery of periodic tables for molecules
Scientists at Tokyo Institute of Technology (Tokyo Tech) develop tables similar to the periodic table of elements but for molecules.
New method for imaging biological molecules
Researchers at Karolinska Institutet in Sweden have, together with colleagues from Aalto University in Finland, developed a new method for creating images of molecules in cells or tissue samples.
How two water molecules dance together
Researchers have gained new insights into how water molecules interact.
More Molecules News and Molecules Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.