Supramolecular complex formation—anthracene macrocycle and C60 fullerene

June 8, 2018, Wiley
Supramolecular complex formation—anthracene macrocycle and C60 fullerene
Credit: Wiley

Saturn is the second largest planet in our solar system and has a characteristic ring. Japanese researchers have now synthesized a molecular "nano-Saturn." As the scientists report in the journal Angewandte Chemie, it consists of a spherical C60 fullerene as the planet and a flat macrocycle made of six anthracene units as the ring. The structure is confirmed by spectroscopic and X-ray analyses.

Nano-Saturn systems with a spherical molecule and a macrocyclic ring have been a fascinating structural motif for researchers. The ring must have a rigid, circular form, and must hold the molecular sphere firmly in its midst. Fullerenes are ideal candidates for the nano-sphere. They are made of carbon atoms linked into a network of rings that form a hollow sphere. The most famous , C60, consists of 60 arranged into 5- and 6-membered rings like the leather patches of a classic soccer ball. The electrons in their double bonds, knows as the π-electrons, are in a kind of "," able to freely move about and have binding interactions with other molecules, such as a macrocycle that also has a "cloud" of π-electrons. The attractive interactions between the electron allow fullerenes to lodge in the cavities of such macrocycles.

A series of such complexes has previously been synthesized. Because of the positions of the electron clouds around the macrocycles, it was previously only possible to make rings that surround the fullerene like a belt or a tire. The ring around Saturn, however, is not like a "belt" or "tire," it is a very flat disc. Researchers working at the Tokyo Institute of Technology and Okayama University of Science (Japan) wanted to properly imitate this at nanoscale.

Their success resulted from a different type of bonding between the "nano-planet" and its "nano-ring." Instead of using the attraction between the π-electron clouds of the fullerene and macrocycle, the team working with Shinji Toyota used the weak attractive interactions between the π-electron cloud of the fullerene and non- π-electron of the carbon-hydrogen groups of the macrocycle.

To construct their "Saturn ," the researchers chose to use anthracene units, molecules made of three aromatic six-membered carbon rings linked along their edges. They linked six of these units into a macrocycle whose cavity was the perfect size and shape for a C60 fullerene. Eighteen hydrogen atoms of the macrocycle project into the middle of the cavity. In total, their interactions with the fullerene are enough to give the complex enough stability, as shown by computer simulations. By using X-ray analysis and NMR spectroscopy, the team was able to prove experimentally that they had produced Saturn-shaped complexes.

Explore further: String of Fullerene Pearls

More information: Yuta Yamamoto et al. Nano-Saturn: Experimental Evidence of Complex Formation of an Anthracene Cyclic Ring with C60, Angewandte Chemie International Edition (2018). DOI: 10.1002/anie.201804430

Related Stories

String of Fullerene Pearls

November 30, 2007

Under an atomic force microscope, the tiny structures look like fragments of nanoscopic pearl necklaces. In reality, the “pearls” are fullerene molecules that are linked together by means of a special fullerene-binding ...

Visualization of molecular soccer balls

May 10, 2018

Fullerenes are composed of 60 carbon atoms joined together in hexagonal rings to form a sphere that resembles a soccer ball. Fullerenes are of great interest to materials scientists because their interesting electronic properties ...

Image: Saturn's B ring peaks

February 19, 2018

While the Winter Olympics is in full swing in PyeongChang, South Korea, and many winter sport fanatics head to snow-clad mountains to get their thrills on the slopes this ski-season, this dramatic mountain scene is somewhat ...

Image: Sliver of Saturn

April 4, 2017

Although only a sliver of Saturn's sunlit face is visible in this view, the mighty gas giant planet still dominates the view.

Recommended for you

Producing defectless metal crystals of unprecedented size

October 19, 2018

A research group at the Center for Multidimensional Carbon Materials, within the Institute for Basic Science (IBS), has published an article in Science describing a new method to convert inexpensive polycrystalline metal ...

Nanodiamonds as photocatalysts

October 19, 2018

Climate change is in full swing and will continue unabated as long as CO2 emissions continue. One possible solution is to return CO2 to the energy cycle: CO2 could be processed with water into methanol, a fuel that can be ...

Researchers unfold secret stability of bendy straws

October 18, 2018

Collapsible dog bowls, bendable medical tubes and drinking straws all seem to work on a common principle, snapping into a variety of mechanically stable and useful states. Despite the many applications for such "designer ...

Shining light on the separation of rare earth metals

October 18, 2018

Inside smartphones and computer displays are metals known as the rare earths. Mining and purifying these metals involves waste- and energy-intense processes. Better processes are needed. Previous work has shown that specific ...

0 comments

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.