With boron 'buckyball' find, nanotechnology advances
The discovery that a cluster of 40 boron atoms can form a hollow molecular 'cage' similar to a buckyball could be a nanotechnology game-changer.
Mon, Jul 14, 2014 at 02:50 PM
When carbon buckyballs, soccerball-shaped molecular structures, were first discovered back in 1985, it essentially launched the nanotech revolution. Now researchers have discovered a new kind of buckyball made of the element boron, which could lead to a whole new line of useful nanomaterials, reports Brown University News.
Classical carbon buckyballs are made of 60 carbon atoms all arranged in pentagons and hexagons to form a hollow ball-like structure that acts like a molecular cage. The newly discovered boron buckyballs, by comparison, are made up of 40 boron atoms. The resulting structure, which consists of 48 triangles, four seven-sided rings and two six-membered rings, is not as smoothly spherical as its carbon counterpart, but it still forms a stable molecular 'cage' just the same.
"This is the first time that a boron cage has been observed experimentally," said Lai-Sheng Wang, the Brown University professor who led the team that made the discovery. "As a chemist, finding new molecules and structures is always exciting. The fact that boron has the capacity to form this kind of structure is very interesting."
Wang and his team were also responsible for the earlier discovery of clusters of 36 boron atoms that form one-atom-thick disks, another important nano-structure that could potentially be stitched together to form an analog to graphene, called borophene. In fact, it was this earlier research that led to the suspicion that 40-atom clusters of boron could be something special too, since they were unusually stable compared to other boron nano-structures.
To identify the precise structure of these 40-atom clusters, Wang and his team required assistance from high-powered supercomputers that could model potential formations of the boron clusters. Over 10,000 possible arrangements were initially identified. Computer simulations also linked each arrangement with its estimated electron binding energy-- a measure of how tightly a molecule holds its electrons.
The team then measured the electron binding energy of the 40-atom clusters produced in the lab and matched them up against the appropriate arrangement identified by the supercomputer simulations. The lab results were consistent with two possible structures — a semi-flat molecule and, sure enough, a buckyball-like spherical cage.
One potential use for the boron buckyballs, which are being called "borospherene," could be as hydrogen storage, since boron's electron deficiency could be ideal for bonding with hydrogen. The tiny boron cages could be used to protect and house the even smaller hydrogen atoms.
"For us, just to be the first to have observed this, that’s a pretty big deal," said Wang. "Of course if it turns out to be useful that would be great, but we don’t know yet. Hopefully this initial finding will stimulate further interest in boron clusters and new ideas to synthesize them in bulk quantities."
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