"It is possible to finely tune the properties of molecules through chemical synthesis to achieve just the right balance of properties needed," says Jonathan Rudick, an assistant professor of chemistry at Stony Brook University. "For example, through chemical synthesis, we can select ranges of the solar spectrum that a molecule will absorb, which has been essential for progress made in the area of organic molecules for solar power."
The National Science Foundation (NSF)-funded scientist is studying a class of molecules known as dendrons, highly branched molecules shaped like wedges or cones, which pack together to form circular or spherical assemblies with nanoscale dimensions. His group aims to develop a new class of nanoscale materials that can be processed like conventional synthetic polymers, yet retain the high structured order found in proteins.
One potential benefit of their work could be in developing a low-cost, low-weight and compact material that could be used to purify large volumes of water, and prove valuable in developing countries where potable water is difficult to find. It also could be useful in large scale water treatment facilities "where you need to be able to purify large volumes quickly, and the less membrane it takes to do that, the better," he says.
This requires creating the tiniest of channels for the water to pass through, which is not as simple as it sounds.
"The composition lining of the hole determines whether the water will go through," he says. "When you get a hole down to being the size of a molecule, then the interactions between the atoms in the water molecule and the atoms that line the hole become critical as to whether or not the water will go through. It's not like shooting water through a faucet."
Dendrons pose a special challenge in that "there is very little order to how the atoms are arranged within their assembly," making it difficult for scientists to manipulate the atoms, Rudick says.
However, peptides, on the other hand, another class of molecules "can take on a helical conformation, in which the atoms are arranged like a spiral staircase," with known locations for each atom, he explains. "Because the location of each atom in the helical molecule is known, we can accurately anticipate the positions of atoms in bundles of helical peptides."
Dendronized helix bundle assemblies also could have a major impact in the development of molecular materials for solar power, he says.
"The active components in organic photovoltaic materials are organic molecules that can absorb light called chromophores," he explains. "The arrangement of chromophores in a film plays an important role in determining whether an absorbed photon of light is transformed into energy we can use.
"Furthermore, the best arrangement of chromophores is not yet known, and will likely vary depending on the particular chromophore being used," he adds. "By incorporating chromophores within the helical bundle portion of our hybrid molecular materials, we will be able to systematically explore how to optimize the performance of solar conversion materials."
Read more at: http://phys.org/news/2014-01-hybrid-molecules-materials-function-nanoscale.html#jCp
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