Synthetic chemist Rebekka Klausen has received a prestigious Brown Investigator Award to design and synthesize three-dimensional silicon polymers revealing novel electronic and quantum phenomena.
"The way I think about it is the frontiers of complexity. What are the most complex silicon structures that can be made?" says Klausen, a professor in the Department of Chemistry at Johns Hopkins University's Krieger School of Arts and Sciences.
The award is designed for mid-career faculty advancing fundamental discoveries in the physical sciences with the potential to seed breakthroughs that benefit society. Brown Investigators are recognized for their curiosity-driven research and receive up to $2 million over five years. The award gives scientists the opportunity to pursue areas of interest in which they have not established themselves.
Klausen was trained as an organic chemist—someone who studies the highly abundant element carbon, found in everything from sugar and proteins to petroleum and plastics. But she was always surprised that the even more abundant element silicon, which sits just below carbon on the periodic table and therefore has similar bonding properties, received much less attention. So her lab at Johns Hopkins has focused on making molecules with silicon-silicon bonds that possess the "beautiful complexity" of organic molecules found in nature.
Klausen's lab does curiosity-driven basic science with the simple aim of exploring silicon's unknowns, but applications have presented themselves. For example, through making hexagons out of silicon and then finding ways to link them into chains, the lab found that silicon molecules are much more flexible than carbon molecules. Many carbon-based plastic products tear easily and are then discarded, which sends waste into the environment, but the researchers found that replacing just a fraction of the carbon atoms with silicon makes the materials much tougher and therefore longer lasting.
"I think this is a great example of how fundamental, basic science observations can have an unanticipated impact on more applied research," Klausen says.
The Brown award will allow Klausen's lab to go beyond silicon hexagons to new, three-dimensional silicon structures and then link them into repeating polymer strands. The new structures, Klausen says, have the potential to push the frontiers of what can be made from them because they have what is known as strain, meaning the bonds or angles are distorted. The lab's research to date suggests that these clusters of silicon atoms are likely to have interesting electronic properties, like unusual colors or the ability to release or store energy. Exploring these properties could unlock new understanding about the polymers and where researchers might follow them next.
"It's a big step forward in our ambition of identifying and making silicon molecules that can give carbon molecules a run for their money," Klausen says. "I expect that studying these molecules will lead us down new directions and make an impact on fields beyond silicon chemistry."
Through the new funding, Klausen is also excited to offer her lab members opportunities to visit other sites to learn new techniques or measurements and then return to train their peers.
Between the new techniques and the uncharted research directions, the possibilities seem almost limitless. "I think what's impactful about this is the investment in really fundamental, open-ended, big-picture questions and basic science," Klausen says.
"The reason it's important to invest in it is because we don't know what future problems will emerge or what knowledge will be relevant when that need arises."
