Simple photochemical method takes advantage of quantum mechanics
Northwestern University chemists have used visible light and extremely tiny nanoparticles to quickly and simply make molecules that are of the same class as many lead compounds for drug development. Driven by light, the nanoparticle catalysts perform chemical reactions with very specific chemical products -- molecules that don't just have the right chemical formulas but also have specific arrangements of their atoms in space. And the catalyst can be reused for additional chemical reactions.
Molecules adsorb on the surface of semiconductor nanoparticles in very specific geometries. The nanoparticles use energy from incident light to activate the molecules and fuse them together to form larger molecules in configurations useful for biological applications.
Credit: Yishu Jiang, Northwestern University
The semiconductor nanoparticles are known as quantum dots -- so small that they are only a few nanometers across. But the small size is power, providing the material with attractive optical and electronic properties not possible at greater length scales.
"Quantum dots behave more like organic molecules than metal nanoparticles," said Emily A. Weiss, who led the research. "The electrons are squeezed into such a small space that their reactivity follows the rules of quantum mechanics. We can take advantage of this, along with the templating power of the nanoparticle surface."
This work, published recently by the journal Nature Chemistry, is the first use of a nanoparticle's surface as a template for a light-driven reaction called a cycloaddition, a simple mechanism for making very complicated, potentially bioactive compounds.
"We use our nanoparticle catalysts to access this desirable class of molecules, called tetrasubstituted cyclobutanes, through simple, one-step reactions that not only produce the molecules in high yield, but with the arrangement of atoms most relevant for drug development," Weiss said. "These molecules are difficult to make any other way."
Weiss is the Mark and Nancy Ratner Professor of Chemistry in the Weinberg College of Arts and Sciences. She specializes in controlling light-driven electronic processes in quantum dots and using them to perform light-driven chemistry with unprecedented selectivity.
The nanoparticle catalysts use energy from visible light to activate molecules on their surfaces and fuse them together to form larger molecules in configurations useful for biological applications. The larger molecule then detaches easily from the nanoparticle, freeing the nanoparticle to be used again in another reaction cycle.
In their study, Weiss and her team used three-nanometer nanoparticles made of the semiconductor cadmium selenide and a variety of starter molecules called alkenes in solution. Alkenes have core carbon-carbon double bonds which are needed to form the cyclobutanes.
The study is titled "Regio- and diastereoselective intermolecular [2+2] cycloadditions photocatalysed by quantum dots." Yishu Jiang, a graduate student in Weiss' lab, is the study's first author.
Amanda Morris | EurekAlert!
Structure of a mitochondrial ATP synthase
19.11.2019 | Science For Life Laboratory
Mantis shrimp vs. disco clams: Colorful sea creatures do more than dazzle
19.11.2019 | University of Colorado at Boulder
Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.
By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...
An international team of scientists, including three researchers from New Jersey Institute of Technology (NJIT), has shed new light on one of the central mysteries of solar physics: how energy from the Sun is transferred to the star's upper atmosphere, heating it to 1 million degrees Fahrenheit and higher in some regions, temperatures that are vastly hotter than the Sun's surface.
With new images from NJIT's Big Bear Solar Observatory (BBSO), the researchers have revealed in groundbreaking, granular detail what appears to be a likely...
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...
Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.
New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...
If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.
Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...
15.11.2019 | Event News
15.11.2019 | Event News
05.11.2019 | Event News
19.11.2019 | Life Sciences
19.11.2019 | Physics and Astronomy
19.11.2019 | Health and Medicine