Researchers develop programmable photocatalyst

Chemical reactions can be controlled using coloured light by means of an intelligent photocatalyst developed by researchers at the Chair of Physical Chemistry at FAU and the Max Planck Institute of Colloids and Interfaces. The colour of the light determines which programmed chemical reactions are triggered by the photocatalyst. The researchers have now published their findings in the journal ‘Angewandte Chemie Int. Ed.’.

Photocatalysts are special materials that use the energy of sunlight or LEDs in order to trigger a desired reaction. These reactions usually produce many products that chemists then have to separate using complex processes, which is why the term poor selectivity is associated with photocatalysts.

In order to specifically synthesise sulphonamides, in other words organosulphur compounds that can be used as antibiotics to treat bacterial infections, researchers at the Max Planck Institute and FAU have created a photocatalyst made of active carbon nitride material. When exposed to light, this material usually produces a mixture of three materials. The intelligent photocatalyst can differentiate between blue, red and green light. With the correct colour of light, it demonstrates high selectivity and produces exclusively sulphonamides. The reaction is automatically linked to the colour of the light. This method could also potentially be used to make the production of sulphonamide antibiotics more sustainable.


Ultrakurzzeitspektrometer

Measurements using ultrafast spectroscopy (image: Christoph Schüßlbauer)

In order to use the smart photocatalyst to produce other specific materials, it is important to find out how it works and why it differs from conventional photocatalysts. The team led by Prof. Dr. Dirk Guldi at the Chair of Physical Chemistry therefore investigated the mechanism of the catalyst using a wide variety of spectroscopic methods that enable the physical properties of materials to be determined by means of the interaction of these materials with light. By using ultrafast spectroscopy in particular, where measurements are carried out at speeds of less than one microsecond, the scientists were able to demonstrate that the activation of oxygen by the photocatalyst plays a decisive role in selectively triggering the desired reaction. ‘Our findings are the first milestone towards intelligent molecules. In future, we could use them to trigger specific reactions and thus manufacture precisely those materials that we require,’ explains Prof. Dr. Guldi.

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