Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Creating a nanospace like no other

24.10.2019

Scientists build a nanocage with antiaromatic walls

Researchers at Tokyo Institute of Technology, the University of Cambridge, and the University of Copenhagen have built a self-assembled nanocage with a very unusual nanospace:


(a) construction of antiaromatic-walled nanospace. (b) X-ray crystal structure with a 3D NICS grid, showing magnetic deshielding experienced within the nanospace. Antiaromaticity effects becomes stronger in the order of yellow < orange < red color.

Credit: Nature

Its walls are made of antiaromatic molecules, which are generally considered too unstable to work with. By overturning assumptions about the limits of nano-chemical engineering, the study creates an entirely new nanospace for scientists to explore. Nanometer-sized cavities are already finding a range of useful applications in chemistry, medicine and environmental science.

Scientists including Masahiro Yamashina of Tokyo Institute of Technology (JSPS Overseas Research Fellow, at that time) and Jonathan R. Nitschke of the University of Cambridge, reporting their work in the journal Nature, describe the construction of a new type of nanospace inside "a self-assembled cage composed of four metal ions with six identical antiaromatic walls."

Until now, many teams have developed nanocages with aromatic walls, but none with antiaromatic compounds, owing to the challenges posed by their inherent instability. Aromaticity refers to a property of ring-shaped organic compounds that makes them highly stable, whereas antiaromaticity describes compounds that are far more reactive, due to a difference in the number of so-called π-electrons shared by the ring. (For a quick summary of the differences between the two types of compounds, refer to Antiaromatic molecule displays record electrical conductance.)

The team's search for a suitable building block for their nanocage led them to a 2012 study by Hiroshi Shinokubo and co-workers in Japan. This study reported the synthesis of an unusually stable, nickel-based antiaromatic compound called norcorrole. Then, drawing on Jonathan R. Nitschke and his group's expertise in subcomponent self-assembly, the team succeeded in building a three nanometer-diameter cage with a norcorrole skeleton.

To investigate the degree of antiaromacity within the cage, the team performed nucleus-independent chemical shift (NICS) calculations. The results indicated that the norcorrole panels appear to work together to enhance antiaromacity. The NICS value was consistently high in the central part of the cage, suggesting that the panels reinforce each other.

The unique environment inside the cage was further tested by encapsulating a series of guest molecules, beginning with coronene which has been already encapsulated within the aromatic cage.

The researchers hypothesized that when exposed to an external magnetic field, guest molecules in an aromatic-walled cage would experience a shielding effect, while those in an antiaromatic-walled cage would experience a deshielding effect.

As predicted by theory, nuclear magnetic resonance (NMR) spectroscopy analyses revealed a deshielding effect attributable to the antiaromatic walls.

All guest molecules tested in the study showed significant downfield chemical shifting, an indicator of the degree of deshielding. The shift differences ranged from 0.7 to 14.9 parts per million. Of these, a carbon nanobelt showed the highest degree of downfield shifting observed so far resulting from an antiaromatic environment.

The cage can be considered as a new type of NMR shift reagent, the researchers say, meaning that it could be a useful tool for structural analysis, ie for interpreting the finest structures of organic compounds.

Future work will focus on investigating chemical reactivity within the nanospace.

###

Related links

The Nitschke Group, Department of Chemistry, University of Cambridge https://www.nitschkegroup-cambridge.com

Department of Chemistry, School of Science https://educ.titech.ac.jp/chem/eng/ Biomimetics: Artificial receptor distinguishes between male and female hormones |Tokyo Tech News https://www.titech.ac.jp/english/news/2019/044145.html

Sweet success: Nanocapsule perfectly binds sucrose in water |Tokyo Tech News https://www.titech.ac.jp/english/news/2017/039190.html

Stabilization of Highly Reactive Reagents upon Encapsulation |Tokyo Tech News https://www.titech.ac.jp/english/news/2014/028504.html

Media Contact

Emiko Kawaguchi
media@jim.titech.ac.jp
81-357-342-975

http://www.titech.ac.jp/english/index.html 

Emiko Kawaguchi | EurekAlert!
Further information:
http://dx.doi.org/10.1038/s41586-019-1661-x
https://www.eurekalert.org/pub_releases/2019-10/tiot-can102319.php

More articles from Life Sciences:

nachricht Pinpointing Pollutants from Space
15.11.2019 | Max-Planck-Institut für Chemie

nachricht Chemists use light to build biologically active compounds
15.11.2019 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

Im Focus: A new quantum data classification protocol brings us nearer to a future 'quantum internet'

The algorithm represents a first step in the automated learning of quantum information networks

Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...

Im Focus: Distorted Atoms

In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.

An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

New laser opens up large, underused region of the electromagnetic spectrum

15.11.2019 | Power and Electrical Engineering

NASA sending solar power generator developed at Ben-Gurion U to space station

15.11.2019 | Power and Electrical Engineering

Typhoons and marine eutrophication are probably the missing source of organic nitrogen in ecosystems

15.11.2019 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>