Scientists from the Gwangju Institute of Science and Technology Develop a Catalyst That Goes Off When Illuminated
GWANGJU, South Korea, January 14, 2022 /PRNewswire/ — In an effort to develop catalysts that allow better spatio-temporal control of chemical reactions, scientists at the Gwangju Institute of Science and Technology have developed a new ““intelligent” catalyst that deactivates under UV illumination. This feat was achieved by strategically combining a well-known ruthenium catalyst with azobenzene, a light-sensitive organic compound. Their findings pave the way for new modes of photolithography and cooperative catalyst systems, the latter of which could be used to synthesize sophisticated chemicals.
Catalysts are compounds that enable and accelerate desired chemical reactions without degrading and are essential in virtually all applied chemistry. Over the past few decades, many researchers have sought to develop what is known as ‘clever‘ catalysts to facilitate the synthesis of sophisticated chemicals. In general, the reactivity of smart catalysts can be controlled by applying an external stimulus, such as lowering the temperature or increasing the acidity of the medium, making them much more versatile tools than conventional catalysts.
In a recent effort to bring a new smart catalyst to the table, scientists at Korea’s Gwangju Institute of Science and Technology zeroed in on a particular organic molecule called azobenzene. This compound undergoes a reversible structural change when illuminated by light of a certain frequency. Although this property had previously been exploited to design light-sensitive polymers and proteins, very few have explored its potential to design smart transition metal catalysts. Thus, the research team, led by Professor Sukwon Hong, attempted to introduce azobenzene into cyclic(alkyl)(amino)carbene-ruthenium (CAAC-Ru), an established catalyst widely used in olefin metathesis reactions for the production of drugs, cosmetics and cosmetics. other complex chemicals. Their study was Posted in ACS catalysts.
They strategically modified CAAC-Ru so that the active site of ruthenium is more or less exposed to the reactants depending on the shape adopted by the inserted azobenzene group. In this way, they produced a pair of photoswitchable catalysts with a twist, as Professor Hong explains: “Unlike previously reported photosensitive catalysts where light activates the catalytic reaction, our catalysts exhibit the opposite behavior; that is, they deactivate when illuminated by ultraviolet (UV) light, providing a new mode of photoswitching.The team also demonstrated the reversibility of the photoswitching mechanism through other experiments, showing that reactions can be turned on and off repeatedly by simply switching the UV light source.
Using light to activate or deactivate a catalyst is convenient because light is both non-invasive and remarkably easy to manipulate with high resolution in time and space. Therefore, the catalysts developed can be leveraged to effectively activate a desired chemical reaction only when needed and exactly where desired. This is crucial for applications such as photolithography, where chemical reactions are used to create microscopic patterns on thin layers using chemical masks. Another interesting application would be the design of a cooperative catalyst system using two different photoswitchable catalysts – one that activates with light and one with the opposite behavior – to aid in the controlled production of complex substances. “In the long term, the development of smarter catalysts will unlock much more sophisticated synthetic mechanisms to produce chemicals that improve people.‘his daily life,“concludes Professor Hong.
Only time will tell what clever uses we will find for these clever catalysts!
Title of the original article: Reversibly Photoswitchable Catalysts for Olefin Metathesis Reactions
Newspaper: ACS catalysis
DO I: https://doi.org/10.1021/acscatal.1c04281
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