LMU chemist Oliver Trapp has designed and synthesized a catalyst which flexibly molds the handedness of the reaction products with which it interacts.
Many chemical compounds contain so-called chiral centers to which functional groups can be attached in either of two orientations. This gives rise to two different forms of the product which are mirror images of one another: Their spatial conformations are related to each other in the same way as right and left hands. Moreover, such configurational pairs – generally referred to as enantiomers – may exhibit different properties. For this reason, synthetic chemists are often faced with the problem of ensuring that the final product has the correct enantiomeric form. Oliver Trapp (Professor of Organic Chemistry at LMU since September 2016) and Golo Storch (a member of his previous research group at Heidelberg University, and currently at Yale University) now report the development of a catalyst that dynamically adapts to the stereochemistry of the compounds with which it interacts, and can progressively select for the desired enantiomer. The work is described in a paper which has just appeared in the journal Nature Chemistry.
Their system is based on a pair of molecular backbones that are known to interact with one another with enantiomeric selectivity. One of these serves as the carrier of the desired product while the other is equipped with a metal catalyst and flexible binding sites that recognize the product. The catalyst interacts transiently and repeatedly with the products of its own action, and can swiftly adjust the configuration of its binding sites. “We ourselves were surprised at how rapidly the catalyst adapts,” Trapp says. These interactions effectively modify the structure of the catalyst in such a way that its stereoselectivity is enhanced. Once the catalyst has recognized the desired enantiomer, its selective efficiency improves with every further catalytic cycle. The final result of this self-amplifying action is that the end-products all have the same chiral structure.
This dynamic adaptability is of great interest in the context of the drug industry’s never-ending search for biologically active compounds. Not only that, it may throw new light on how stereoselective chemical reactions operate in biological systems, where one normally finds only one chiral form of any given compound. “The world in which we live is monochiral,” says Trapp. “Researchers have not yet found a convincing explanation for this. But it is conceivable that the functional principle of supermolecular interaction which we have exploited was also crucial for the origin of life.”
Technology marries light-harvesting nanoantennas to high-reaction-rate catalysts
In a find that could transform some of the world’s most energy-intensive manufacturing processes, researchers at Rice University’s Laboratory for Nanophotonics have unveiled a new method for uniting light-capturing photonic nanomaterials and high-efficiency metal catalysts.
Each year, chemical producers spend billions of dollars on metal catalysts, materials that spur or speed up chemical reactions. Catalysts are used to produce trillions of dollars worth of chemical products. Unfortunately, most catalysts only work at high temperatures or high pressure or both. For example, the U.S. Energy Information Agency estimated that in 2010, just one segment of the U.S. chemical industry, plastic resin production, used almost 1 quadrillion British thermal units of energy, about the same amount of energy contained in 8 billion gallons of gasoline.
Nanotechnology researchers have long been interested in capturing some of the worldwide catalysis market with energy-efficient photonic materials, metallic materials that are tailor-made with atomic precision to harvest energy from sunlight. Unfortunately, the best nanomaterials for harvesting light — gold, silver and aluminum — aren’t very good catalysts, and the best catalysts — palladium, platinum and rhodium — are poor at capturing solar energy.
The new catalyst, which is described in a study this week in the Proceedings of the National Academy of Sciences, is the latest innovation from LANP, a multidisciplinary, multi-investigator research group headed by photonics pioneer Naomi Halas. Halas, who also directs Rice’s Smalley-Curl Institute, said a number of studies in recent years have shown that light-activated “plasmonic” nanoparticles can be used to increase the amount of light absorbed by adjacent dark nanoparticles. Plasmons are waves of electrons that slosh like a fluid across the surface of tiny metallic nanoparticles. Depending upon the frequency of their sloshing, these plasmonic waves can interact with and harvest the energy from passing light.
Results Suggest a More Efficient Way to Convert Solar and Wind Power to Renewable Fuels
With a combination of theory and clever, meticulous gel-making, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and the University of Toronto have developed a new type of catalyst that’s three times better than the previous record-holder at splitting water into hydrogen and oxygen – the vital first step in making fuels from renewable solar and wind power.
The research, published today in the journal Science, outlines a potential way to make a future generation of water-splitting catalysts from three abundant metals – iron, cobalt and tungsten – rather than the rare, costly metals that many of today’s catalysts rely on.
“The good things about this catalyst are that it’s easy to make, its production can be very easily scaled up without any super-advanced tools, it’s consistent, and it’s very robust,” said Aleksandra Vojvodic, a SLAC staff scientist with the SUNCAT Center for Interface Science and Catalysis who led the theoretical side of the work.
Rice University scientists find possible replacement for platinum as catalyst
Rice University chemists who developed a unique form of graphene have found a way to embed metallic nanoparticles that turn the material into a useful catalyst for fuel cells and other applications.
Read more: Laser-burned graphene gains metallic powers