Now at the molecular level: electric motors

Now at the molecular level: electric motors

The molecular structure of the electric molecular motor is shown. Credit: Northwestern University

Electric cars, which are powered by macroscopic electric motors, are increasingly spreading on our streets and highways. These quiet, environmentally friendly machines began nearly 200 years ago when physicists took the first small steps to bring electric motors to the world.

Now an interdisciplinary team led by Northwestern University has created an electric motor you can’t see with the naked eye: an electric motor on the molecular scale.

This early work—a motor that can convert electrical energy into unidirectional motion at the molecular level—has implications for materials science and especially medicine, as an electric molecular motor can combine with biomolecular motors in the human body.

“We have taken molecular nanotechnology to another level,” said Sir Fraser Stoddart of Northwestern University, who received the 2016 Nobel Prize in Chemistry for his work designing and manufacturing molecular machines. “This elegant chemistry uses electrons to effectively drive a molecular motor, just like a macroscopic motor. While this area of ​​chemistry is still in its infancy, I predict one day these tiny motors will make a huge difference in medicine.”

Stoddart, MD, Professor of Chemistry on the Board of Trustees of the Weinberg College of Arts and Sciences, is a co-author of the study. The research was conducted in close collaboration with Dean Astomian, a molecular machine theorist and professor at the University of Maine, and William Goddard, a computational chemist and professor at Caltech. Long Zhang, a postdoctoral fellow in Stoddart’s lab, is the paper’s first author and co-author.

The molecular motor is only 2 nanometers wide, and it is the first to be mass-produced in abundance. The engine is easy to make, runs fast, and produces virtually no waste.

The magazine published today (January 11) the study and an informative summary of it nature.

The research team focused on a specific type of ring-linked molecule known as catenanes, which are held together by strong mechanical bonds, so that the components can move freely relative to each other without disintegrating. (Decades ago, Stoddart played a key role in creating the mechanical bond, a new type of chemical bond that led to the development of molecular machines.)

The electric molecular motor is specifically based on a [3]catenane whose components – a ring crosslinked with two identical rings – are redox-active, that is, they undergo unidirectional motion in response to changes in voltage potential. The researchers discovered that two loops were needed to achieve this one-way motion. Experiments have shown that a [2]The catenan, which has one ring interlocked with one ring, does not act as a motor.

The synthesis and operation of molecules that perform the actuator function – converting external energy into directional motion – has challenged scientists in the fields of chemistry, physics and molecular nanotechnology for some time.

To achieve this breakthrough, Stoddart, Zhang, and their team at Northwestern spent more than four years designing and installing their electric molecular motor. This included a year working with Astumian and Caltech’s Goddard of UMaine to complete quantum mechanical calculations to explain the working mechanism behind the engine.

“Controlling the relative motion of components at the molecular level is a huge challenge, so collaboration was critical,” Zhang said. “Working with experts in synthesis, measurements, computational and theoretical chemistry enabled us to develop an electric molecular motor that works in solution.”

A few examples of single-molecular electric motors have been reported, but they require extreme operating conditions, such as the use of a very high vacuum, and they produce waste.

The researchers said the next steps for their electric molecular motor are to attach several motors to an electrode surface to act on the surface and eventually do some useful work.

“The achievement we are reporting today is a testament to the creativity and productivity of our young scientists as well as their willingness to take risks,” Stoddart said. “This work gives me and the team tremendous satisfaction.”

more information:
Long Zhang et al, Electric Molecular Motor, nature (2023). DOI: 10.1038/s41586-022-05421-6

Provided by Northwestern University

the quote: Now at the Molecular Scale: Electric Motors (2023, January 11) Retrieved January 12, 2023 from

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