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Polyfluoroalkyl and perfluoroalkyl substances (PFASs) are found in many everyday consumer products, often because of their high thermal and chemical stabilities, as well as their hydrophobic and oleophobic properties 1 . However, the inert carbon–fluorine (C–F) bonds that give PFASs their properties also provide resistance to decomposition through defluorination, leading to long-term persistence in the environment, as well as in the human body, raising substantial safety and health concerns 1 , 2 , 3 , 4 – 5 . Despite recent advances in non-incineration approaches for the destruction of functionalized PFASs, processes for the recycling of perfluorocarbons (PFCs) as well as polymeric PFASs such as polytetrafluoroethylene (PTFE) are limited to methods that use either elevated temperatures or strong reducing reagents. Here we report the defluorination of PFASs with a highly twisted carbazole-cored super-photoreductant KQGZ . A series of PFASs could be defluorinated photocatalytically at 40–60 °C. PTFE gave amorphous carbon and fluoride salts as the major products. Oligomeric PFASs such as PFCs, perfluorooctane sulfonic acid (PFOS), polyfluorooctanoic acid (PFOA) and derivatives give carbonate, formate, oxalate and trifluoroacetate as the defluorinated products. This allows for the recycling of fluorine in PFASs as inorganic fluoride salt. The mechanistic investigation reveals the difference in reaction behaviour and product components for PTFE and oligomeric PFASs. This work opens a window for the low-temperature photoreductive defluorination of the ‘forever chemicals’ PFASs, especially for PTFE, as well as the discovery of new super-photoreductants. Photocatalysis at 40–60 °C is shown to be able to defluorinate perfluoroalkyl substances, known as ‘forever chemicals’, allowing the recycling of fluorine in polyfluoroalkyl and perfluoroalkyl substances as inorganic fluoride salt.

Organic halides are highly useful compounds in chemical synthesis, in which the halide serves as a versatile functional group for elimination, substitution and cross-coupling reactions with transition metals or photocatalysis 1 , 2 – 3 . However, the activation of carbon–fluorine (C–F) bonds—the most commercially abundant organohalide and found in polyfluoroalkyl substances (PFAS), or ‘forever chemicals’—is much rarer. Current approaches based on photoredox chemistry for the activation of small-molecule C–F bonds are limited by the substrates and transition metal catalysts needed 4 . A general method for the direct activation of organofluorines would have considerable value in organic and environmental chemistry. Here we report an organic photoredox catalyst system that can efficiently reduce C–F bonds to generate carbon-centred radicals, which can then be intercepted for hydrodefluorination (swapping F for H) and cross-coupling reactions. This system enables the general use of organofluorines as synthons under mild reaction conditions. We extend this method to the defluorination of PFAS and fluorinated polymers, a critical challenge in the breakdown of persistent and environmentally damaging forever chemicals. An organic photoredox catalyst system efficiently reduces C–F bonds, generating carbon-centred radicals for hydrodefluorination and cross-coupling reactions, enabling the general use of organofluorines as synthons and breaking down environmentally damaging forever chemicals.

Summary Poly‐ and perfluorinated chemicals, including perfluorinated alkyl substances (PFAS), are pervasive in today’s society, with a negative impact on human and ecosystem health continually emerging. These chemicals are now subject to strict government regulations, leading to costly environmental remediation efforts. Commercial polyfluorinated compounds have been called ‘forever chemicals’ due to their strong resistance to biological and chemical degradation. Environmental cleanup by bioremediation is not considered practical currently. Implementation of bioremediation will require uncovering and understanding the rare microbial successes in degrading these compounds. This review discusses the underlying reasons why microbial degradation of heavily fluorinated compounds is rare. Fluorinated and chlorinated compounds are very different with respect to chemistry and microbial physiology. Moreover, the end product of biodegradation, fluoride, is much more toxic than chloride. It is imperative to understand these limitations, and elucidate physiological mechanisms of defluorination, in order to better discover, study, and engineer bacteria that can efficiently degrade polyfluorinated compounds. This review discusses recent knowledge pertaining to the microbial degradation of polyfluorinated compounds and PFAS. It further explores underlying reasons why this biodegradation is so rare in nature and posits prospects for future discovery and implementation.

We report the defluorination of the per- and polyfluoroalkyl substances (PFAS) chemical perfluorooctane sulfonate (PFOS) by deep ultraviolet light assisted electrocatalysis, using the industrial thermoelement materials Constantan and Nichrome as anodes. Surface analysis of wire anodes after anodic conditioning in aqueous base, which enabled uptake of incidental iron from the electrolyte, showed the in situ formation of surface nickel–iron (oxy)hydroxides, which are active electrocatalysts for PFOS defluorination. The defluorination activity of Constantan wire was higher than that of Nichrome wire, which was unstable under PFOS defluorination conditions. Constantan wire mesh completely defluorinated PFOS over a 48-hour period, maintaining 85.5% defluorination after 120 h. The decrease in PFOS defluorination efficiency was attributed to an increase in charge transfer resistance due to the buildup of transition metal hydroxides, oxyhydroxides, or oxides on the wire surface, rather than anode dissolution. Our results provide necessary mechanistic insights into the stability of commercially widely available nickel alloys for the development of economically viable aqueous PFAS remediation systems.

Controlling radical selectivity within nanoreactors remains a formidable challenge due to the inherent high reactivity and short half-lives of reactive species. Herein, we report a novel size-matched nanoconfinement strategy using a cobalt-nickel-layered double hydroxide (CoNi-LDH) nanoreactor for the highly selective generation and stabilization of sulfate radicals (SO4∙−) via piezoelectric activation of peroxymonosulfate (PMS). By precisely tailoring the LDH interlayer spacing to 5.27 Å to match the kinetic diameter of SO4∙−, the nanoreactor effectively suppresses non-selective side reactions and radical quenching. Consequently, the CoNi-LDH achieves an unprecedented reaction rate (kobs = 0.40 min−1) and superior defluorination efficiency (78.9%) for fluoroquinolone antibiotics, significantly outperforming non-size-confined counterparts. Mechanistic insights reveal a synergistic pathway where piezo-generated hot electrons, mediated by Ni sites, accelerate the Co2+/Co3+ redox cycle to ensure long-term catalytic stability. The robustness of this nanoconfined system is further demonstrated by its exceptional tolerance to complex water matrices and its practical operability in a continuous-flow reactor. This study provides a pioneering approach for spatial radical control at the nanoscale to achieve efficient and targeted environmental remediation.

Owing to the low atomic weight of fluorine, rechargeable fluoride-based batteries could offer very high energy density. However, current batteries need to operate at high temperatures that are required for the molten salt electrolytes. Davis et al. push toward batteries that can operate at room temperature, through two advances. One is the development of a room-temperature liquid electrolyte based on a stable tetraalkylammonium salt–fluorinated ether combination. The second is a copper–lanthanum trifluoride core-shell cathode material that demonstrates reversible partial fluorination and defluorination reactions. Science , this issue p. 1144 Fluoride ion–conducting liquid electrolytes enable room-temperature cycling of fluoride ion electrochemical cells. Fluoride ion batteries are potential “next-generation” electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion–conducting electrolytes are known only in the solid state. We report a liquid fluoride ion–conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper–lanthanum trifluoride (Cu@LaF 3 ) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion–mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology.

Fluorinated organic chemicals, such as per- and polyfluorinated alkyl substances (PFAS) and fluorinated pesticides, are both broadly useful and unusually long-lived. To combat problems related to the accumulation of these compounds, microbial PFAS and organofluorine degradation and biosynthesis of less-fluorinated replacement chemicals are under intense study. Both efforts are undermined by the substantial toxicity of fluoride, an anion that powerfully inhibits metabolism. Microorganisms have contended with environmental mineral fluoride over evolutionary time, evolving a suite of detoxification mechanisms. In this perspective, we synthesize emerging ideas on microbial defluorination/fluorination and fluoride resistance mechanisms and identify best approaches for bioengineering new approaches for degrading and making organofluorine compounds. Microbial degradation and biosynthesis of fluorinated compounds is a field of increasing importance, but is hampered by the significant toxicity of fluoride. Here authors discuss emerging ideas on microbial defluorination/fluorination and fluoride resistance mechanisms, providing guidance on how this knowledge can guide future bioengineering approaches.

A major challenge in per- and polyfluoroalkyl substances (PFAS) remediation has been their structural and chemical diversity, ranging from ultra-short to long-chain compounds, which amplifies the operational complexity of water treatment and purification. Here, we present an electrochemical strategy to remove PFAS from ultra-short to long-chain PFAS within a single process. A redox-polymer electrodialysis (redox-polymer ED) system leverages a water-soluble redox polymer with inexpensive nanofiltration membranes, facilitating the treatment of varied chain lengths of PFAS without membrane fouling. Our approach combines both ion migration by electrodialysis (for PFAS with chain lengths ≤C4) and electrosorption strategies (for PFAS with chain lengths ≥C6) to eliminate approximately 90% of ultra-short-, short-chain, and long-chain PFAS. At the same time, we achieve continuous desalination of the source water down to potable water level. The redox-polymer ED exhibits remarkable PFAS removal in real source water scenarios, including from matrices with 10,000 times higher salt concentrations, as well as secondary effluents from wastewaters. Additionally, the removed PFAS is mineralized with a defluorination performance between 76-100% by electrochemical oxidation, highlighting the viability of integrating the separation step with a reactive degradation process. PFAS remediation is challenging due to their diverse chain lengths, complicating water treatment. Here, the authors present an electrochemical approach for the removal of ultra-short to long-chain PFAS in a single process by integrating redox-electrodialysis and electrosorption.

Constructing organic fluorophosphines, vital drug skeletons, through the direct fluorination of readily available alkyl phosphonates has been impeded due to the intrinsic low electrophilicity of P V and the high bond energy of P═O bond. Here, alkyl phosphonates are electrophilically activated with triflic anhydride and N -heteroaromatic bases, enabling nucleophilic fluorination at room temperature to form fluorophosphines via reactive phosphine intermediates. This approach facilitates the late-stage (radio)fluorination of broad dialkyl and monoalkyl phosphonates. Monoalkyl phosphonates derived from targeted drugs, including cyclophosphamide, vortioxetine, and dihydrocholesterol, are effectively fluorinated, achieving notable yields of 47−71%. Radiofluorination of medically significant 18 F-tracers and synthons are completed in radiochemical conversions (radio-TLC) of 51−88% and molar activities up to 251 ± 12 GBq/μmol (initial activity 11.2 GBq) within 10 min at room temperature. Utilizing a phosphonamidic fluoride building block (BFPA), [ 18 F]BFPA-Flurpiridaz and [ 18 F]BFPA-E[c(RGDyK)] 2 demonstrate high-contrast target imaging, excellent pharmacokinetics, and negligible defluorination. Constructing organic fluorophosphines via direct fluorination of alkyl phosphonates is challenging. Herein, the authors show that alkyl phosphonates are electrophilically activated with triflic anhydride and N -heteroaromatic bases, enabling nucleophilic fluorination at room temperature to form fluorophosphines via reactive phosphine intermediates.

Tertiary stereogenic centres containing one fluorine atom are valuable for medicinal chemistry because they mimic common tertiary stereogenic centres containing one hydrogen atom, but they possess distinct charge distribution, lipophilicity, conformation and metabolic stability 1 – 3 . Although tertiary stereogenic centres containing one hydrogen atom are often set by enantioselective desymmetrization reactions at one of the two carbon–hydrogen (C–H) bonds of a methylene group, tertiary stereocentres containing fluorine have not yet been constructed by the analogous desymmetrization reaction at one of the two carbon–fluorine (C–F) bonds of a difluoromethylene group 3 . Fluorine atoms are similar in size to hydrogen atoms but have distinct electronic properties, causing C–F bonds to be exceptionally strong and geminal C–F bonds to strengthen one another 4 . Thus, exhaustive defluorination typically dominates over the selective replacement of a single C–F bond, hindering the development of the enantioselective substitution of one fluorine atom to form a stereogenic centre 5 , 6 . Here we report the catalytic, enantioselective activation of a single C–F bond in an allylic difluoromethylene group to provide a broad range of products containing a monofluorinated tertiary stereogenic centre. By combining a tailored chiral iridium phosphoramidite catalyst, which controls regioselectivity, chemoselectivity and enantioselectivity, with a fluorophilic activator, which assists the oxidative addition of the C–F bond, these reactions occur in high yield and selectivity. The design principles proposed in this work extend to palladium-catalysed benzylic substitution, demonstrating the generality of the approach. Enantioselective activation of a single C–F bond in a difluoromethylene group is achieved using a chiral transition metal catalyst and a fluorophilic activator.