Major advance made in imaging of a single-molecule switch

February 2, 2016
Molecular conductance

Development of future technologies will be greatly aided by understanding and extracting molecular-level characteristics. A University of Tsukuba research group has established a three-dimensional probe that can depict the switching of a single molecule between two different conformations, induced by a mechanical force.

This achievement is particularly encouraging because of the markedly different levels of conductance of electrical charge by the molecule in these different conformations, which could be used in molecular-sized devices.

This study involved binding individual molecules between two silicon electrodes, creating a robust "molecular junction." Altering the distance between these electrodes—in other words, applying different levels of to the individual molecules attached between them—showed that the electrical current conducted by these molecules changed. For one molecule tested, the electrical current changed gradually as the distance decreased or increased, as would be expected. However, for another molecule, there was an abrupt change in the conductance, which was shown to correspond to a switch in this molecule's overall conformation.

"We created such molecular junctions for divinylbenzene and diethynylbenzene," explains lead author Miki Nakamura of the Graduate School of Pure and Applied Sciences in the University of Tsukuba. "Using our dynamic probe based on scanning tunneling microscopy, we were able to show that applying a mechanical force to the former resulted in a gradual change in the conductance of the molecule. However, for diethynylbenzene, we saw the conductance dramatically change, which we modeled as a switch from a cis to a trans conformation and back again."

This work builds on earlier studies that successfully characterized the specific properties of individual molecules, such as flexibility, and spin properties. There were also previous suggestions that abrupt switching in the level of of a molecule is related to its ability to transition rapidly between two different, stable conformations. However, the Tsukuba team are the first to directly image these changes.

Group leader Dr. Shigekawa of the University of Tsukuba Faculty of Pure and Applied Sciences is excited about the potential for this new development. "Our work could have widespread implications for basic research on the electronic properties of molecules, as well as for the development of molecular machines," he says. "The ability to combine solid state semiconductor electrodes with into this type of junction boosts the potential for further advances in molecular computing."

Explore further: Electronic switches on the molecular scale

More information: Miki Nakamura et al. Mechanically activated switching of Si-based single-molecule junction as imaged with three-dimensional dynamic probe, Nature Communications (2015). DOI: 10.1038/ncomms9465

Related Stories

Electronic switches on the molecular scale

November 25, 2014

A molecular electronic switch is a junction created from individual molecules that can alternate between two or more stable states, making the switch act as a conductor or an insulator. These switches show promise for future ...

Study demonstrates an electronic switch based on stereoisomerism

February 25, 2015

As devices get smaller and smaller, scientists are running up against limits to how small one can feasibly construct a circuit using bulk materials. Molecular circuits offer a possible solution to overcoming these size constraints, ...

DNA-based electromechanical switch demonstrated

December 11, 2015

A team of researchers from the University of California, Davis and the University of Washington have demonstrated that the conductance of DNA can be modulated by controlling its structure, thus opening up the possibility ...

S-t-r-e-t-c-h-i-n-g electrical conductance to the limit

December 5, 2011

Individual molecules have been used to create electrical components like resistors, transistors and diodes, that mimic the properties of familiar semiconductors. But according to Nongjian (NJ) Tao, a researcher at the Biodesign ...

Manipulating molecules for a new breed of electronics

February 20, 2011

( -- In research appearing in today’s issue of the journal Nature Nanotechnology, Nongjian “NJ” Tao, a researcher at the Biodesign Institute at Arizona State University, has demonstrated a clever ...

Recommended for you

The microscopic origin of efficiency droop in LEDs

November 21, 2017

Light-emitting diodes—or LEDs, as they are commonly known—have been slowly replacing incandescent light bulbs in applications ranging from car taillights to indicators on electronics since their invention in the 1960s.

Borophene shines alone as 2-D plasmonic material

November 20, 2017

An atom-thick film of boron could be the first pure two-dimensional material able to emit visible and near-infrared light by activating its plasmons, according to Rice University scientists.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.