Chemists at the University of Oregon have discovered a way to create carbon-based molecules with a distinct structural feature: interlocking rings.
These linked-together molecules, like other nanomaterials, have interesting properties that can be “tuned” by changing their size and chemical makeup. As a result, they have the potential to be useful for a wide range of applications, including specialized sensors and new types of electronics.
“It’s a new topology for carbon nanomaterials, and we’re finding new properties that we haven’t been able to see before,”
said first author James May, a graduate student in chemistry professor Ramesh Jasti’s laboratory.
Nanohoops And Other Structures
Credit: Nature Chemistry (2023). DOI: 10.1038/s41557-022-01106-9
Although numerous kinds of interlocking molecules have been created by other labs, the Jasti lab’s technique enables the linking of structures resembling carbon nanotubes. Chemists will be able to experiment with the structure in many different ways and learn more about the new materials’ characteristics as a result.
“You can create structures you can’t with other methods,”
Jasti said.
His team, for example, used the method to create three interlocked rings, as well as a rod-like structure with multiple rings that can slide up and down. The breakthrough stemmed from Jasti’s research on nanohoops, which are carbon atom rings that are a scaled-down version of long, skinny carbon nanotubes.
“Because we’re able to make these circular structures at will, I started thinking, could you make things that just don’t exist in nature?That’s where this idea of interlocking rings came in,”
Jasti said.
Metal Kickstart
It required a creative approach to identify a sequence of chemical reactions that could produce the intricate ring structures. The key to their solution is the addition of a metal atom to one ring.
That metal initiates the chemical reaction that produces the second ring, forcing it to occur within the first ring. When that reaction occurs, the second ring becomes trapped and locked together with the first ring.
“We’re able to get chemistry to happen inside of a space where it might never occur,”
May said.
If the size of the interlocked molecules changes, the rings are arranged differently, or new chemical elements are added, the molecules behave differently.
Flexible Electronics, Glowing Sensors
Scientists could improve the material to do exactly what they want it to do by making nanoscale modifications. Scientists are still exploring all of the potential applications because the class of materials is so new.
However, Jasti’s group is most interested in their potential as sensors, where a change in the position of the rings in response to a specific chemical could result in a fluorescent glow. They could also be used to develop dynamic biomedical materials or flexible electronics.
“Typical carbon nanomaterials like carbon nanotubes, graphene or even diamond are static materials. Here, we have created new types of carbon nanomaterials that maintain their fascinating electrical and optical properties but now have capability to do things like rotate, compress, or stretch,”
he said.
Reference: May, J.H., Van Raden, J.M., Maust, R.L. et al. Active template strategy for the preparation of π-conjugated interlocked nanocarbons. Nat. Chem. (2023).
