Subscribe free to our newsletters via your
. 24/7 Space News .




Subscribe free to our newsletters via your




















NANO TECH
New aspect of atom mimicry for nanotechnology applications
by Staff Writers
Tokyo, Japan (SPX) Dec 07, 2016


This image shows the structure of Divalent Phenylazomenthine dendrimer, Comparison of the DPA and Bohr atom model, and 1D/2D supramolecular polymer. Image courtesy Tokyo Institute of Technology. For a larger version of this image please go here.

In nanotechnology control is key. Control over the arrangements and distances between nanoparticles can allow tailored interaction strengths so that properties can be harnessed in devices such as plasmonic sensors. Now researchers at Tokyo Institute of Technology use dendrimers that mimic the electron valency of atoms and link them into arrays using molecules that coordinate with the dendrimer as they would form a covalent electron pair in their valence shell - "electron pair mimicry".

Kimihisa Yamamoto, Ken Albrecht, and colleagues at Tokyo Tech considered the dendritic polyphenylazomethine (DPA), which has a structure that branches out from a central core.

"Lewis acid" molecules coordinate to the "Lewis base" sites of DPA. Analysis of the ratio of SnCl2 Lewis acid molecules coordinating with each dendrimer revealed step increases from 2 to 4 to 8 to 16, which mimics the valency of the Bohr atom that has 2, 8, 18, and 32 electrons in the 1st, 2nd, 3rd , and 4th orbitals. This reflects the increase in the number of molecules that can coordinate with the dendrimer with increasing distance from the core, as the number of dendrimer branches and electron density increases.

Yamamoto's team analysed the coordination of DPA with a stronger binding Lewis acid - triphenylmethylium (TPM) - bound to the rod-like molecule phenylene ethynylene. The phylene ethynlene backbone is rigid enough that the acid cations at either end cannot then bind to the same dendrimer. Instead a polymer chain of dendrimers forms.

Using a different starting dendrimer (ZnPG4 instead of DPAG4) - which has a core valency of four instead of two - led to the formation of two dimensional polymerisation of the dendrimers, producing a 2D array of nanocontainers for that can accumulate other Lewis acids into the outer orbitals.

The work describes "a new aspect of atom mimicry" conclude the researchers. "The geometry and pitch can be controlled by the design of the dendrimer and the linker and are potentially applicable to plasmonics (after seed-mediated growth) and nanoelectrode grids (which are also useful as electrocatalysts)."

The Bohr model of the atom set out by Niels Bohr and Ernest Rutherford in 1913 describes the atom as a positive nucleus surrounded by electrons in different shells or energy levels. Each shell has a prescribed number of electrons that can occupy it - that is, two electrons can occupy the first shell, eight the next, and eighteen the next, and so on.

While there are aspects of the atom behaviour that the model does not cover, it is particularly successful at explaining the spectral emission lines. When excited, an electron can jump to the next energy level. When it returns to the initial energy level, the difference in the energies is emitted as light at the specific wavelength equivalent to the energy difference.

Where a shell is not full, the atom can bond with another chemical species. In this way the valency of an atom describes how full the electron shell is and how readily bonds can form. The electron density gradient of dendrimers moving radially from the core to the more branched outer regions dictates how many Lewis acid coordinating molecules it can accommodate and in this way it mimics the energy levels of the Bohr atom.

A Lewis acid is a chemical species that can accept a lone pair of electrons from a chemical that can donate a lone pair, that is, from a Lewis base. This behaviour is defined by the electron structure of the chemical. Lewis acids include acidic compounds but also metal cations.

When the dendrimer coordinates with the Lewis acids it takes the place of the Lewis base that would donate an electron pair. The researchers describe the di-Lewis acid compound (linker molecule) as electron pair mimicry.

When two chemicals react the amount of light absorbed can change depending on how much light the products versus the reactants absorb. If the products and reactants absorb the same amount of light at a particular wavelength, it is described as the isosbestic point.

The researchers used isosbestic points to identify the step increases in Lewis acid reacting with the dendrimers. A wavelength shift in the isosbestic point indicates coordination of the Lewis acid to the subsequent layer of the dendrimer.

Research paper


Comment on this article using your Disqus, Facebook, Google or Twitter login.

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Tokyo Institute of Technology
Nano Technology News From SpaceMart.com
Computer Chip Architecture, Technology and Manufacture






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
NANO TECH
Supersonic spray yields new nanomaterial for bendable, wearable electronics
Chicago IL (SPX) Nov 25, 2016
A new, ultrathin film that is both transparent and highly conductive to electric current has been produced by a cheap and simple method devised by an international team of nanomaterials researchers from the University of Illinois at Chicago and Korea University. The film is also bendable and stretchable, offering potential applications in roll-up touchscreen displays, wearable electronics, flexi ... read more


NANO TECH
Cold plasma freshens up French fries

Orbital ATK Ends 2016 with Three Successful Cargo Resupply Missions to ISS

Space Food Bars Will Keep Orion Weight Off and Crew Weight On

Russian Space Sector Overcomes Failures

NANO TECH
Russia to Launch Fewer Spacecraft in 2016 Than US, China for First Time

Soyuz-U Carrier Rocket Installed to Baikonur Launching Pad

Ariane 5's impressive 75 in-a-row launch record

Vega ready for GOKTURK-1A to be encapsulated

NANO TECH
CaSSIS Sends First Images from Mars Orbit

First views of Mars show potential for ESA's new orbiter

ExoMars space programme needs an extra 400 million euros

Opportunity team onsidering a new route due to boulder field

NANO TECH
China launches 4th data relay satellite

Material and plant samples retrieved from space experiments

Chinese astronauts return to earth after longest mission

China completes longest manned space mission yet

NANO TECH
ESA looks at how to catch a space entrepreneur

Thales and SENER to jointly supply optical payloads for space missions

Citizens' space debate: the main findings and the future

Two-year extensions confirmed for ESA's science missions

NANO TECH
Shape matters when light meets atom

New technology of ultrahigh density optical storage researched at Kazan University

Earth's 'technosphere' now weighs 30 trillion tons

A watershed moment in understanding how H2O conducts electricity

NANO TECH
Biologists watch speciation in a laboratory flask

Life before oxygen

Timing the shadow of a potentially habitable extrasolar planet

Fijian ants began farming 3 million years ago

NANO TECH
New analysis adds to support for a subsurface ocean on Pluto

Pluto follows its cold, cold heart

New Analysis Supports Subsurface Ocean on Pluto

Mystery solved behind birth of Saturn's rings




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement