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PFAS: Silicon-based superacids could break down “forever chemicals”
Researchers at TU Berlin have succeeded in synthesising a new class of extremely strong Lewis acids based on silicon. These compounds could play a crucial role in the degradation of harmful PFAS.
A research team from the UniSysCat Cluster of Excellence at TU Berlin has for the first time synthesised silicon-based super-Lewis acids containing an additional halogen atom. These compounds rank among the strongest Lewis acids known to date and are capable of attacking highly stable chemical bonds such as the carbon–fluorine linkages in PFAS. The findings have been published in Nature Chemistry.
One remarkable property of the new compounds is that they are not consumed during the reaction. Instead, they can regenerate, thus acting catalytically – a decisive advantage for potential applications in recycling processes and green chemistry.
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Electron hunger enables PFAS degradation
The stability of PFAS is due to their particularly strong carbon–fluorine bonds. Breaking them requires substances with an exceptionally high affinity for electron pairs. The newly developed super-Lewis acids meet this requirement: the combination of a silicon atom with a halogen atom generates an extreme electron deficiency, enabling the cleavage of PFAS bonds.
The synthesis process is complex, as the substances must be handled under inert conditions. Neither oxygen nor water can come into contact with the compounds. The breakthrough was achieved using protolysis, a method previously applied in carbon chemistry and now transferred to silicon chemistry.
Quantum chemistry provides predictive power
In addition to experimental work, theoretical calculations played a crucial role. Quantum chemical methods allowed the researchers to predict the acidity of the molecules purely from their structure. These predictions were later verified experimentally using NMR spectroscopy.
According to the team, the new super-Lewis acids hold great promise for tackling PFAS contamination in both environmental and industrial contexts. Since they regenerate, even small amounts of the acids could suffice to neutralise large volumes of these persistent pollutants.
Source: Oestreich, M. et al., Catalytic degradation of PFAS using silicon-based super-Lewis acids. Nat. Chem. (2025).
