The creative power of chemistry lies in the ability of scientists to shape matter in unprecedented ways and generate new substances and materials with unique and advantageous properties. Now, researchers in the Light4Function project are looking to the next step, aiming to use light to control the timing and location of chemical and physical processes, as Professor Stefan Hecht explains
Researchers shine new light on chemical processes
There is a
long history of chemists designing sophisticated molecules to create new pharmaceuticals and novel materials. This work has underpinned a great deal of technical and industrial development, but the level of sophistication is still way behind mother Nature’s machinery. Now researchers in the Light4Function project are looking to the next step, aiming to develop new methods to remotely yet precisely control chemical processes. “We are investigating the use of light as a trigger to control where and when chemical reactions take place,” explains Professor Stefan Hecht, the project’s Principal Investigator. The project aims to design and implement new functional photoswitchable systems, drawing inspiration from the natural world. “Nature uses stimuli – such as the presence of a messenger molecule, for example a hormone, or light – to trigger an event. The latter offers great advantages since light can be applied with exquisite spatio-temporal as well as energetic resolution – it’s the ideal remote-control,” says Professor Hecht. This work is inspired by observations of the natural world, where light triggers and drives important processes. Professor
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Hecht points to the example of photosynthesis. “In photosynthesis, light generates a proton gradient across a membrane, and that drives synthesis of adenosine triphosphate,” he explains. With modern spectroscopy techniques, it is now possible to pulse light at very high frequencies, which allows researchers to control the timing of a chemical reaction using light. “Nowadays you can pulse light
Photoswitches Light can also be applied externally, in a non-invasive manner, offering a way to precisely control the outcome of a chemical reaction without adding a chemical. However, one component has to interact with the light; Professor Hecht and his colleagues hold deep expertise in this area, particularly in the design of a specific type of molecules, so-called photoswitches.
We are investigating the use of light as a trigger to control where and when chemical reactions take place at the atto-second frequency (10 -18 seconds). Even fast chemical processes occur on a timescale longer than 10 -15 seconds and typically chemistry is much slower as it is limited by diffusion, which occurs at 10 -10 seconds. So light gives you absolutely exquisite control over time and we can initiate a reaction very precisely,” outlines Professor Hecht. “For spatial resolution, light is inferior to techniques such as Atomic Force Microscopy and Scanning Tunnelling Microscopy, but with state-of-the-art equipment you can go well below the so-called diffraction limit.”
“These molecules can exist in two different forms. Light can turn the molecules from one form into another. We want these two forms to behave very differently – like Dr. Jekyll and Mr. Hyde – because we want to exploit their differences to regulate various chemical and physical processes,” he says. The project’s agenda includes fundamental research into these photoswitches, of which there are several different types. “We are looking to both design new photoswitches and improve existing photoswitches. We want them to switch reliably and very efficiently, ideally upon exposure to
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