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In order to improve current efficieny, a novel flow and circulation electrolytic system was developed using a Pd tube cathode coated on the inside with Pd black, and packed with Pd catalyst supported on carbon fiber, which is surrounded by a platinum wire anode. This new electrochemical flow system was shown to be highly effective for the cathodic hydrogenation of unsaturated compounds and the dehalogenation of various aromatic halides, including PCB precursors. [ABSTRACT FROM AUTHOR]

Chlorinated and fluorinated nitrophenols (HNCs) are widely used in agriculture and industry, with a global market valued at USD $25 billion, one which is expected to grow by 5% by 2030. However, these compounds pose significant environmental risks; they are classified as toxic by the International Agency for Research on Cancer (IARC). Existing treatment methods include advanced oxidation, adsorption, and bioremediation, though to date, there has been only limited research on fungal remediation of these halogenated pollutants. This study aims to explore a sustainable approach by using fungi's potential to degrade HNCs in minimal media. Ten fungi were selected through literature screening; Caldariomyces fumago and Curvularia sp. were highly effective, degrading over 50% of 2-chloro-4-nitrophenol (2C4NP) and 80% of 5-fluoro-2-nitrophenol (5F2NP) within 24 and 48 h, respectively. Additionally, five strains showed degradation potential for fluorinated compounds. Further studies revealed C. fumago could degrade up to 1 mM of chlorinated compounds and 12 mM of fluorinated compounds, far exceeding any known environmental concentrations of HNCs; importantly, ecotoxicology tests demonstrated reductions in toxicity of 77% and 85%, respectively. This work highlights fungi's underexplored ability to degrade toxic HNCs, offering a sustainable mycoremediation strategy and positioning mycology as a critical tool for future environmental remediation efforts. [ABSTRACT FROM AUTHOR]

Developing the films of N‐containing unsubstituted poly(p‐phenylene) (PPP) films for diverse applications is significant and highly desirable because the replacement of sp2 C atoms with sp2 N atoms will bring novel properties to the as‐prepared polymers. In this research, an electrochemical‐dehalogenation polymerization strategy is employed to construct two N‐containing PPP films under constant potentials, where 2,5‐diiodopyridine (DIPy) and 2,5‐dibromopyrazine (DBPz) are used as starting agents. The corresponding polymers are named CityU‐23 (for polypyridine) and CityU‐24 (for polypyrazine). Moreover, it is found that both polymers can form films in situ on different conductive substrates (i.e., silicon, gold, ITO, and nickel), satisfying potential device fabrication. Furthermore, the as‐obtained thin films of CityU‐23 and CityU‐24 exhibit good performance of alkaline hydrogen evolution reaction with the overpotential of 212.8 and 180.7 mV and the Tafel slope of 157.0 and 122.4 mV dec−1, respectively. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) have garnered significant interest within the scientific community due to their distinctive ability to act as organic semiconductors responsive to visible light. This unique attribute makes them up-and-coming candidates for facilitating photocatalytic organic reactions. Herein, two donor–acceptor COFs, TPE-BSD-COF and TPE-BD-COF, have been designed and synthesized by incorporating electron-rich tetraphenylethylene and electron-deficient benzoselenadiazole and benzothiadiazole units into the framework through a Schiff-base polycondensation reaction. Both COFs exhibit exceptional crystallinity and enduring porosity. TPE-BSD-COF and TPE-BD-COF exhibit broad light absorption capabilities, a narrow optical band gap, and low electrochemical impedance spectrum (EIS) levels, indicating that the two COFs are effective heterogeneous photocatalysts for the reductive dehalogenation of phenacyl bromide derivatives under blue LED irradiation. A high photocatalytic yield of 98% and 95% was achieved by TPE-BSD-COF and TPE-BD-COF catalysts, respectively, within only one hour. [ABSTRACT FROM AUTHOR]

Mixed plastic packaging waste sorting residue (MPO323) was treated by thermal pyrolysis to utilize pyrolysis oil and char. The pyrolysis oil was found to contain aromatic and aliphatic hydrocarbons. The chlorine and bromine contents were as high as 40,000 mg/kg and 200 mg/kg, respectively. Additionally, other elements like sulfur, phosphorous, iron, aluminum, and lead were detected, which can be interpreted as impurities relating to the utilization of oils for chemical recycling. The pyrolysis char showed high contents of potentially active species like silicon, calcium, aluminum, iron, and others. To enhance the content of aromatic hydrocarbons and to reduce the level of contaminants, pyrolysis oil was reformed with the corresponding pyrolysis char to act as an active material in a fixed bed. The temperature of the reactor and the flow rate of the pyrolysis oil feed were varied to gain insights on the cracking and reforming reactions, as well as on performance with regard to decontamination. [ABSTRACT FROM AUTHOR]

Fluorescent lead halide perovskite quantum dots (LH PQDs) micropatterns hold great potential for photonic applications. However, current photolithography for LH PQDs micropatterning is hindered by their incompatibility with traditional photolithography methods, which involve development processes using numerous solvents and exhibit poor stability due to the ionic characteristics of LH PQDs. Herein, a direct in situ photolithography to fabricate CsPbBr3 PQDs micropatterns based on ultraviolet‐C light‐driven debromination is developed. Using this approach, fluorescent CsPbBr3 PQDs micropatterns with high theoretical information storage capacity (up to 10750205) can be achieved in a single step, without the need for tedious development processes. Furthermore, the fabricated CsPbBr3 PQDs micropatterns show high stability, remaining undamaged even after immersion in water for 6 months. The combination of excellent optical properties, development‐free process, high stability, and low cost makes the in situ photolithography strategy very promising for patterning LH PQDs toward photonic integrations. [ABSTRACT FROM AUTHOR]

We present the strategic design of donor‐acceptor cyanoarene‐based photocatalysts (PCs) aiming to augment beneficial PC degradation for halogen atom transfer (XAT)‐induced dehalogenation reactions. Our investigation reveals a competitive nature between the catalytic cycle and the degradation pathway, with the degradation becoming dominant, particularly for less activated alkyl halides. The degradation behavior of PCs significantly impacts the efficiency of the XAT process, leading to exploration into manipulating the degradation behavior in a desirable direction. Recognizing the variation in the nature and rate of PC degradation, as well as its influence on the reaction across the range of PC structures, we carefully engineered the PCs to develop a pre‐catalyst, named 3DP‐DCDP‐IPN. This pre‐catalyst undergoes rapid degradation into an active form, 3DP‐DCDP‐Me‐BN, exhibited an enhanced reducing ability in its radical anion form to induce better PC regeneration and consequently effectively catalyzes the XAT reaction, even with a challenging substrate. [ABSTRACT FROM AUTHOR]

Humic electron mediators can facilitate the reductive dehalogenation of organohalogenated compounds by accelerating electron transfer. To investigate the effect of humic electron mediators on the microbial anaerobic reductive dechlorination of Polychlorinated biphenyls (PCBs), three types of humic electron mediators, humin (HM), humic acid (HA), and anthraquinone-2,6-disulfonic acid (AQDS, HA analogs), were added to PCB dechlorination cultures enriched from different sources in terrestrial and marine environments (T and M cultures). The results showed that meta- and para-site dechlorination occurred in the M culture, while only meta-site dechlorination occurred in the T culture. The dechlorination process N and the dechlorination process H or H' are presented in both cultures. HM enhanced PCB dechlorination metabolic activity in both cultures mainly by promoting meta-site dechlorination. HA showed a weak promoting effect on the M culture by promoting para-chlorine removal but inhibited the dechlorination metabolism of the terrestrial-origin culture, inhibiting meta-chlorine removal. AQDS showed inhibitory effects on both cultures by inhibiting the microbial removal of meta-chlorine. High-throughput sequencing and qPCR results suggest that HM is not a carbon source for the potential dechlorinating metabolism of Dehalococcoides but may promote reductive dechlorination by changing the community structure, and AQDS may inhibit anaerobic reductive dechlorination of PCBs by inhibiting the growth of Dehalococcoides. This study provides insights into the mechanism of enhancing PCB microbial dechlorination mediated by humic substances and plays a significant role in extending the application prospects of PCBs bioremediation technology. [ABSTRACT FROM AUTHOR]

Halogenated organic compounds are persistent pollutants that pose a serious threat to human health and the safety of ecosystems. Cobamides are essential cofactors for reductive dehalogenases (RDase) in organohalide-respiring bacteria (OHRB), which catalyze the dehalogenation process. This review systematically summarizes the impact of cobamides on organohalide respiration. The catalytic processes of cobamide in dehalogenation processes are also discussed. Additionally, we examine OHRB, which cannot synthesize cobamide and must obtain it from the environment through a salvage pathway; the co-culture with cobamide producer is more beneficial and possible. This review aims to help readers better understand the importance and function of cobamides in reductive dehalogenation. The presented information can aid in the development of bioremediation strategies. [ABSTRACT FROM AUTHOR]

We established a straightforward electrochemical dihalogenation (F, Cl, and Br) process for gem‐difluoroalkenes. This reaction exhibits a broad functional group tolerance and has been effectively utilized in the construction of complex molecules. The subsequent synthetic transformations of the products have highlighted the adaptable nature of the dihalogenated compounds, demonstrating their potential application in drug discovery and the investigation of innovative materials. The effective utilization of the dihalogenated product for 18F‐labeling represents a novel approach in generating highly potent 18F‐labeled tracers. [ABSTRACT FROM AUTHOR]

To assess the performance of hazardous waste sites remediation technologies like in situ chemical oxidation (ISCO) with persulfate (S2O82−) researchers must periodically measure concentrations of target contaminants. Due to the presence of relatively high concentrations of the residual oxidant expected in many samples, the standard analytical method requires the addition of a relatively high concentration of ascorbic acid to prevent the oxidation process from continuing after sample collection. We discovered that addition of ascorbic acid quencher results in a radical chain reaction that transforms two common halogenated solvents (i.e., tetrachloroethene and hexachloroethane). To avoid the artifact associated with the radical chain reaction, a small quantity of n-hexane can be added to aqueous samples to extract target compounds and protect them from the radical chain reaction initiated by addition of the quencher. We recommend the use of this alternative sample preservation method whenever high concentrations of residual S2O82− are expected to be present in water samples that are contaminated with halogenated solvents.

Despite the extensive application of advanced oxidation processes (AOPs) in water treatment, the efficiency of AOPs in eliminating various emerging contaminants such as halogenated antibiotics is constrained by a number of factors. Halogen moieties exhibit strong resistance to oxidative radicals, affecting the dehalogenation and detoxification efficiencies. To address these limitations of AOPs, advanced reduction processes (ARPs) have been proposed. Herein, a novel nucleophilic reductant—namely, the carbon dioxide radical anion (CO2·−)—is introduced for the simultaneous degradation, dehalogenation, and detoxification of florfenicol (FF), a typical halogenated antibiotic. The results demonstrate that FF is completely eliminated by CO2·−, with approximately 100% of Cl− and 46% of F− released after 120 min of treatment. Simultaneous detoxification is observed, which exhibits a linear response to the release of free inorganic halogen ions (R2 = 0.97, p 75%) in degrading a series of halogenated antibiotics, including chloramphenicol (CAP), thiamphenicol (THA), diclofenac (DLF), triclosan (TCS), and ciprofloxacin (CIP). The system shows high tolerance to the pH of the solution and the presence of natural water constituents, and demonstrates an excellent degradation performance in actual groundwater, indicating the strong application potential of CO2·−-based ARPs in real life. Overall, this study elucidates the feasibility of CO2·− for the simultaneous degradation, dehalogenation, and detoxification of halogenated antibiotics and provides a promising method for their regulation during water or wastewater treatment.

This article proposes a milder approach for C(sp2=−H functionalization of 2,2‐disubstituted cyclopentene‐1,3‐dione via formal 1° amination utilizing water as a solvent. In addition, this approach also offers C(sp2)−O, C(sp2)−I bond formation for the first time using sodium azide. The said highly scalable transformation does not require any prefunctionalization of the starting material. Moreover, this methodology is metal free, requires no ligand and all these reactions are carried out in an open‐air atmosphere with broad substrate scope. We have also explored a novel BF3.OEt2 mediated dehalogenation using mild reaction conditions. [ABSTRACT FROM AUTHOR]

We report a family of donor‐acceptor thermally activated delayed fluorescent (TADF) compounds based on derivatives of DMAC‐TRZ, that are strongly photoreducing. Both Eox and thus E*ox could be tuned via substitution of the DMAC donor with a Hammett series of p‐substituted phenyl moieties while Ered remained effectively constant. These compounds were assessed in the photoinduced dehalogenation of aryl halides, and analogues bearing electron withdrawing groups were found to produce the highest yields. Substrates of up to Ered=−2.72 V could be dehalogenated at low PC loading (1 mol %) and under air, conditions much milder than previously reported for this reaction. Spectroscopic and chemical studies demonstrate that all PCs, including literature reference PCs, photodegrade, and that it is these photodegradation products that are responsible for the reactivity. [ABSTRACT FROM AUTHOR]

Catalytic defunctionalization of complex molecules has attracted significant attention in organic synthesis. This reaction enables common functional groups to serve as "traceless handles" for the new bond construction. In this mini-review, we have summarized the latest advances, methodologies and mechanistic insights into the selective cleavage of C-C and C-X bonds catalysed by cobalt complexes, shedding light on their increasing importance in modern chemical synthesis. The content of this review is categorized according to the type of functional group being removed from molecules. [ABSTRACT FROM AUTHOR]

Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile; TPN) is an environmentally persistent fungicide that sees heavy use in the USA and is highly toxic to aquatic species and birds, as well as a probable human carcinogen. The chlorothalonil dehalogenase from Pseudomonas sp. CTN-3 (Chd, UniProtKB C9EBR5) degrades TPN to its less toxic 4-OH-TPN analog making it an exciting candidate for the development of a bioremediation process for TPN; however, little is currently known about its catalytic mechanism. Therefore, an active site residue histidine-114 (His114) which forms a hydrogen bond with the Zn(II)-bound water/hydroxide and has been suggested to be the active site acid/base, was substituted by an Ala residue. Surprisingly, ChdH114A exhibited catalytic activity with a kcat value of 1.07 s−1, ~ 5% of wild-type (WT) Chd, and a KM of 32 µM. Thus, His114 is catalytically important but not essential. The electronic and structural aspects of the WT Chd and ChdH114A active sites were examined using UV–Vis and EPR spectroscopy on the catalytically competent Co(II)-substituted enzyme as well as all-atomistic molecular dynamics (MD) simulations. Combination of these data suggest His114 can quickly and reversibly move nearly 2 Å between one conformation that facilitates catalysis and another that enables product egress and active site recharge. In light of experimental and computational data on ChdH114A, Asn216 appears to play a role in substrate binding and preorganization of the transition-state while Asp116 likely facilitates the deprotonation of the Zn(II)-bound water in the absence of His114. Based on these data, an updated proposed catalytic mechanism for Chd is presented. [ABSTRACT FROM AUTHOR]

Four melanin polymers prepared from different precursors (5,6‐dihydroxyindole, 5,6‐dihydroxyindole 2‐carboxylic acid, 1,8‐dihydroxynaphthalene and dopamine) have been adopted as photocatalysts in the reductive dehalogenation of a series of model α‐halogen carbonyl derivatives. The best performing melanin was that obtained from 5,6‐dihydroxyindole 2‐carboxylic acid, which allowed to dehalogenate efficiently both bromomalonate esters and phenacyl bromide; on the other hand, chloromalonate esters were almost unreactive under the same reaction conditions. Electrochemical and control experiments enabled to elucidate the reaction mechanism, demonstrating the key role of electrons as charge carriers in the observed photocatalytic process. [ABSTRACT FROM AUTHOR]

Biological regulation often depends on reversible reactions such as phosphorylation, acylation, methylation, and glycosylation, but rarely halogenation. A notable exception is the iodination and deiodination of thyroid hormones. Here, we report detection of bromotyrosine and its subsequent debromination during Drosophila spermatogenesis. Bromotyrosine is not evident when Drosophila express a native flavin-dependent dehalogenase that is homologous to the enzyme responsible for iodide salvage from iodotyrosine in mammals. Deletion or suppression of the dehalogenase-encoding condet (cdt) gene in Drosophila allows bromotyrosine to accumulate with no detectable chloro-or iodotyrosine. The presence of bromotyrosine in the cdt mutant males disrupts sperm individualization and results in decreased fertility. Transgenic expression of the cdt gene in late-staged germ cells rescues this defect and enhances tolerance of male flies to bromotyrosine. These results are consistent with reversible halogenation affecting Drosophila spermatogenesis in a process that had previously eluded metabolomic, proteomic, and genomic analyses. [ABSTRACT FROM AUTHOR]

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Cadmium sulfide (CdS)-based photocatalysts are prepared following a hydrothermal procedure (with CdCl2 and thiourea as precursors). The HydroThermal material annealed (CdS-HTa) is crystalline with a band gap of 2.31 eV. Photoelectrochemical investigation indicates a very reducing photo-potential of −0.9 V, which is very similar to that of commercial CdS. CdS-HTa, albeit having similar reducing properties, is more active than commercial CdS in the reductive dehalogenation of 2,2-dichloropropionic acid (dalapon) to propionic acid. Spectroscopic, electro-, and photoelectrochemical investigation show that photocatalytic properties of CdS are correlated to its electronic structure. The reductive dehalogenation of dalapon has a double significance: on one hand, it represents a demanding reductive process for a photocatalyst, and on the other hand, it has a peculiar interest in water treatment because dalapon can be considered a representative molecule of persistent organic pollutants and is one of the most important disinfection by products, whose removal from the water is the final obstacle to its complete reuse. HPLC-MS investigation points out that complete disappearance of dalapon passes through 2-monochloropropionic acid and leads to propionic acid as the final product. CdS-HTa requires very mild working conditions (room temperature, atmospheric pressure, natural pH), and it is stable and recyclable without significant loss of activity. [ABSTRACT FROM AUTHOR]

Background: Macroalgae, especially reds (Rhodophyta Division) and browns (Phaeophyta Division), are known for producing various halogenated compounds. Yet, the reasons underlying their production and the fate of these metabolites remain largely unknown. Some theories suggest their potential antimicrobial activity and involvement in interactions between macroalgae and prokaryotes. However, detailed investigations are currently missing on how the genetic information of prokaryotic communities associated with macroalgae may influence the fate of organohalogenated molecules. Results: To address this challenge, we created a specialized dataset containing 161 enzymes, each with a complete enzyme commission number, known to be involved in halogen metabolism. This dataset served as a reference to annotate the corresponding genes encoded in both the metagenomic contigs and 98 metagenome-assembled genomes (MAGs) obtained from the microbiome of 2 red (Sphaerococcus coronopifolius and Asparagopsis taxiformis) and 1 brown (Halopteris scoparia) macroalgae. We detected many dehalogenation-related genes, particularly those with hydrolytic functions, suggesting their potential involvement in the degradation of a wide spectrum of halocarbons and haloaromatic molecules, including anthropogenic compounds. We uncovered an array of degradative gene functions within MAGs, spanning various bacterial orders such as Rhodobacterales, Rhizobiales, Caulobacterales, Geminicoccales, Sphingomonadales, Granulosicoccales, Microtrichales, and Pseudomonadales. Less abundant than degradative functions, we also uncovered genes associated with the biosynthesis of halogenated antimicrobial compounds and metabolites. Conclusion: The functional data provided here contribute to understanding the still largely unexplored role of unknown prokaryotes. These findings support the hypothesis that macroalgae function as holobionts, where the metabolism of halogenated compounds might play a role in symbiogenesis and act as a possible defense mechanism against environmental chemical stressors. Furthermore, bacterial groups, previously never connected with organohalogen metabolism, e.g., Caulobacterales, Geminicoccales, Granulosicoccales, and Microtrichales, functionally characterized through MAGs reconstruction, revealed a biotechnologically relevant gene content, useful in synthetic biology, and bioprospecting applications. 7KFSwtia72NY8FA2HCcej3 Video Abstract [ABSTRACT FROM AUTHOR]

A ring‐expansion process for the biomass derivative Cyrene obtained from levoglucosenone has been developed using gem‐dihalocyclopropanes as intermediates. The process involves conversion of Cyrene to an enamine, reaction with an in situ generated dihalocarbene, and then ring‐opening. Competition between endocyclic and exocyclic olefinic products was switchable using solvent and temperature, and ring‐expanded alkenyl halides were obtained in 50–64 % yield from Cyrene. Under extended heating, dehalogenation occurred giving homologated levoglucosenone in 25 % overall yield from Cyrene in 3 steps. [ABSTRACT FROM AUTHOR]

AbstractThere are mounting concerns over the high concentrations of non-biogenic, toxic halogenated organic compounds being liberated into the ecosystem. Therefore, this study’s isolation of a novel bacterium from a contaminated stream in Fatsa, Ordu, Turkey, adept in degrading 2,2-dichloropropionic (of 2,2-DCP) is a welcome endeavor. The ability of the bacterial isolate to utilize 2,2-DCP as the sole carbon and energy source was discovered when the bacterium was observed to grow well on liquid minimal media containing 20 mM of 2,2-DCP, showing a doubling time of 14.2 h. The following genetic and biochemical characterizations revealed that the 16S rRNA sequence of the fatsa001strain is identical (99%) to Pseudomonas fluorescence, after which the sequence was deposited in the NCBI GenBank as Pseudomonas sp. strain fatsa001 (MN098848). The halogen-degrading ability of the P. fluorescens fatsa001 bacterium was again confirmed by the PCR data, which showed the presence of a conserved group of amino acids from the group I dehalogenase gene. It worth mentioning here that this is the first report on a P. fluorescence bacterial strain with the ability to degrade toxic 2,2-DCP. The detoxification ability of this bacterium envisages its practicality as an in situ environmental bioremediation agent. [ABSTRACT FROM AUTHOR]

Photoactive main-group complexes have been relatively underexplored in photocatalytic applications. Herein, we report a family of indium(III) complexes (In-1–In-4) containing pyridylpyrrolide ligands with different amounts of methyl groups, which all exhibit intense visible-light absorption as well as blue-green emission with nanosecond emission lifetimes and emission quantum yields of 6.7–12.5%. Electrochemical studies and quantum chemical calculations indicate that their (photo-)redox processes involve only ligand-centered events, which efficiently mediate photocatalytic dehalogenation and olefin reduction. [ABSTRACT FROM AUTHOR]

In this paper, the synthesis of a novel tetra-phenol π-extended dihydrophenazine is reported. The obtained derivative presents marked reducing properties in the excited state and was exploited as an organo-photocatalyst in dehalogenation and C–C bond formation reactions. These results underline the great potential of functionalized π-extended dihydrophenazines as organo-photocatalysts. [ABSTRACT FROM AUTHOR]

• Tourmaline enhanced the reductive dechlorination efficiency of Desulfitobacterium hafniense. • Tourmaline was able to guide the dechlorination pathway of chlorophenols. • The role of electric field in the process of reductive dechlorination was explored. • Tourmaline had good application prospects in the field of environmental remediation. The dehalogenation of organohalides has been a research hotspot in bioremediation field; however, the influence of tourmaline, a natural ore that can generate spontaneous electric field, on organohalide-respiring bacteria (OHRB) and their dechlorination process is not well known. In this study, the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol (2,3-DCP) by Desulfitobacterium hafniense DCB-2T were explored. The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L, which shortened the total time required for dechlorination reaction to 72 hr. Besides, tourmaline amendment also increased the proportion of 2-chlorophenol (2-CP) from 18% to 30% of end products, while that of 3-CP decreased correspondingly. The theoretical calculations showed that the bond charge of the ortho -substituted chlorine declined from -0.179 to -0.067, and that of meta -substituted chlorine increased from -0.111 to -0.129, which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP. Overall, tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium ,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a lyophilization protocol was established for storable and ready-to-use halohydrin dehalogenase (HHDH) from Agrobacterium radiobacter AD1 (HheC), as a model enzyme. HheC showed high activity preservation after the lyophilization procedure, even in the absence of lyoprotectants. Freeze-dried HheC exhibited higher residual activity compared to the liquid form when stored at 50 °C. Among tested additives the formulation with glycine was found to be the best choice regarding the mechanical strength of the lyophilized pellets. Besides, the results revealed significant stability of dry HheC exposed to MTBE, toluene, and 2-MeTHF. However, no activity of the lyophilized HheC was observed in the dehalogenation of 1,3-dichloro-2-propanol (1,3-DCP) in non-aqueous organic media. This study showed that the lyophilization method provides a convenient way for long-term storage of HHDH enzymes and could have an impact on their wider application in the research and industrial biotechnology. [Display omitted] • Freeze-drying of Agrobacterium radiobacter (HheC) halohydrin dehalogenase was studied. • High HheC resilience towards freeze-drying stress was established. • Long-term storage of HheC is provided by freeze-drying. • Glycine and Na 2 HPO 4 were the most effective additives. • Lyophilized HheC shows high resistance to elevated temperatures and organic solvents. [ABSTRACT FROM AUTHOR]

2,2’-Bis(4-dimethylaminophenyl)- and 2,2'-dicyclohexyl-1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazole ((N-DMBI)2 and (Cyc-DMBI)2) are quite strong reductants with effective potentials of ca. −2 V vs ferrocenium/ferrocene, yet are relatively stable to air due to the coupling of redox and bond-breaking processes. Here, we examine their use in accomplishing electron transfer-induced bond-cleavage reactions, specifically dehalogenations. The dimers reduce halides that have reduction potentials less cathodic than ca. −2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The potentials of the halides that can be reduced in this way, quantum-chemical calculations, and steady-state and transient absorption spectroscopy suggest that UV irradiation accelerates the reactions via cleavage of the dimers to the corresponding radical monomers.

In this paper, the kinetic study of the reaction between substituted 1,4-benzoquinones (RBQs) and Na2SO3 (S(IV)) is presented in aqueous solutions at different pH values and reagent concentrations. The stoichiometry of the reaction is 1:2 RBQs:S(IV) and one equivalent of chloride ion was also detected as a product when using mono- (2-CBQ) or dichloro-benzoquinones (2,5-DCBQ; 2,6-DCBQ) as reactants. This shows that reductive dehalogenation occurs instead of simple reduction to the corresponding substituted 1,4-hydroquinones (RBQHs) and quinone bisulfites are formed, analogously to the addition of bisulfite ion to carbonyl compounds. Various sulfonated quinones have been identified as products by electrospray mass spectrometry. Kinetic traces at different wavelengths were obtained by the stopped-flow technique with spectrophotometric detection, a kinetic fitting program (ZiTa) was used to fit a multi-step model to the data. A detailed mathematical evaluation of the reaction scheme was carried out under non-pseudo-first order conditions showing that our model can be fitted with a double exponential function even when none of the reagents are in large excess. [ABSTRACT FROM AUTHOR]

Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed. [ABSTRACT FROM AUTHOR]

Herein we have disclosed metal‐free 1,8‐diazabicyclo(5.4.0)undec‐7‐ene (DBU)‐catalyzed protocol for the deformylative/dehalogenative carbonylation and Michael addition of β‐bromovinyl aldehydes with acrylates and carbonylation followed by etherification with benzyl bromides to synthesize δ‐oxo esters and vinyl ethers respectively in good yields under an open atmosphere with broad substrate scope. Regeneration of starting material from vinyl ethers, organo‐catalytic and nucleophilic behavior of DBU is also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • PCB was co-pyrolyzed in fixed and fluidized bed (FB) pyrolyzers with Ca-based additives. • Catalytic and dehalogenation capacities of CaO, Ca(OH)2, and CaO + Ca(OH)2 were compared. • CaO reduced the halogen content of bio-oil up to 80 and 92% in fixed bed and FB. • Halide fixation in the solid phase by additives was more effective in FB than fixed bed. • Up to 40.6% liquid recovery was achieved in a FB containing CaO + Ca(OH) 2. This study compares the impact of the calcium-based additives and the pyrolyzer on the recovery and the halide content of the oil produced from the pyrolysis of paper-laminated phenolic resin printed circuit boards (FR2-PCB). The preliminary experiments showed that the maximum liquid recovery (40.6%) was achieved in a fluidized bed pyrolyzer containing a 50:50 mixture of CaO and Ca(OH) 2 operating at T = 620 °C and PCB-to-additive ratio (FR2/A) = 5.4 g/g for 22 min. Extra tests were then carried out under these conditions in fixed and fluidized bed pyrolyzers to separately explore the impact of CaO, Ca(OH) 2 , and CaO + Ca(OH) 2 on the liquid recovery (L R) and the halogen content of the non-solid products. In the fluidized bed, L R in the presence of CaO, Ca(OH) 2 , and CaO + Ca(OH) 2 was 34.5%, 41.2%, and 38.9 wt%, respectively. The fraction of phenolic compounds in the pyrolysis oil ranged from 86% to 93%, about 1–3% higher than the corresponding values in the fixed bed. Using additives led to lower halide content in the pyrolysis oil of the fluidized bed than that of the fixed bed. However, the opposite trend was observed in the absence of additives. Regardless of the type of pyrolyzer, Ca(OH) 2 was more successful than CaO in increasing L R , whereas CaO was more effective than Ca(OH) 2 in pyrolysis oil dechlorination. Co-pyrolysis of FR2-PCB and CaO + Ca(OH) 2 in a fluidized bed reactor was identified as a practical approach to enhance the recovery of pyrolysis oil comprising only 5% of the original halogen content of the feedstock. [ABSTRACT FROM AUTHOR]

In this study, we present a straightforward and highly effective photo-triggered hydrogenation method for aryl halides, devoid of transition-metal catalysts. Through the synergistic utilization of light, PhNHNH2, and a base, we have successfully initiated the desired radical-mediated hydrogenation process. Remarkably, utilizing mild reaction conditions, a wide range of aryl halides, including fluorides, chlorides, bromides, and iodides, can be selectively transformed into their corresponding (hetero)arene counterparts, with exceptional yields. Additionally, this approach demonstrates a remarkable compatibility with diverse functional groups and heterocyclic compounds, highlighting its versatility and potential for use in various chemical transformations. [ABSTRACT FROM AUTHOR]

Reductive dehalogenases are corrinoid and iron–sulfur cluster–containing enzymes that catalyze the reductive removal of a halogen atom. The oxygen-sensitive and membrane-associated nature of the respiratory reductive dehalogenases has hindered their detailed kinetic study. In contrast, the evolutionarily related catabolic reductive dehalogenases are oxygen tolerant, with those that are naturally fused to a reductase domain with similarity to phthalate dioxygenase presenting attractive targets for further study. We present efficient heterologous expression of a self-sufficient catabolic reductive dehalogenase from Jhaorihella thermophila in Escherichia coli. Combining the use of maltose-binding protein as a solubility-enhancing tag with the btuCEDFB cobalamin uptake system affords up to 40% cobalamin occupancy and a full complement of iron–sulfur clusters. The enzyme is able to efficiently perform NADPH-dependent dehalogenation of brominated and iodinated phenolic compounds, including the flame retardant tetrabromobisphenol, under both anaerobic and aerobic conditions. NADPH consumption is tightly coupled to product formation. Surprisingly, corresponding chlorinated compounds only act as competitive inhibitors. Electron paramagnetic resonance spectroscopy reveals loss of the Co(II) signal observed in the resting state of the enzyme under steady-state conditions, suggesting accumulation of Co(I)/(III) species prior to the rate-limiting step. In vivo reductive debromination activity is readily observed, and when the enzyme is expressed in E. coli strain W, supports growth on 3-bromo-4-hydroxyphenylacetic as a sole carbon source. This demonstrates the potential for catabolic reductive dehalogenases for future application in bioremediation. [ABSTRACT FROM AUTHOR]

Due to its favorable excited-state physicochemical properties, indium oxide (In2O3) has widely captured attention as a potentially great photocatalyst. However, an inferior charge separation efficiency limits its application. Recently, an increasing amount of evidence has demonstrated that the construction of surface defects is an effective strategy to boost photocatalytic performances. In this work, a ruthenium (Ru) species was successfully introduced into the lattice of In2O3 nanoparticles through co-precipitation and thermal treatment. It was found that the content of surface oxygen vacancies was directly related to the amount of Ru3+ doping, which further determines the separation efficiency of photogenerated carriers. As a result, the 0.5% Ru-In2O3 samples enriched with oxygen vacancies exhibit dramatically enhanced photocatalytic dehalogenation performances of decabromodiphenyl ether and hexabromobenzene, about four times higher than that of the pure In2O3 nanoparticles. This study emphasized the significance of the surface defects of the photocatalyst and may provide a valuable strategy to prepare highly active photocatalysts for photocatalytic dehalogenation reactions. [ABSTRACT FROM AUTHOR]

The effect of ionic liquids on the separation of chlorinated anionic dyes such as Mordant Blue 9 (MB9) or Acid Yellow 17 (AY17) via ion exchange has been investigated in model aqueous solutions that simulate wastewater from the textile dyeing industry. The effect of ionic liquids chemical nature on the separation efficiency of mentioned dyes has been compared. It was found that especially ionic liquid based on quaternary ammonium salts comprising two or three long alkyl chains bound to the quaternary ammonium nitrogen (typically benzalkonium chloride or Aliquat 336) are very effective for the separation of both studied MB9 and AY17 from aqueous solution. In addition, the innovative technique has been developed for the reactivation of spent ionic liquids which is based on the chemical reduction of the formed ion pairs using NaBH4/NiSO4, NaBH4/Na2S2O5 or Raney Al-Ni alloy/NaOH. Thus, only NaBH4/NiSO4 in co-action with Al-Ni alloy enables both effective reduction of the azo bond and subsequent hydrodechlorination of emerging chlorinated aromatic amines. The efficiency of tested dyes separation or regeneration of ion pairs was evaluated by determination of the absorbance at wavelength of the maximum absorbance, of the Chemical Oxidation Demand (COD), and of the Adsorbables Organically bound Halogens (AOX). The formation of ion pairs or products of reduction and hydrodechlorination of these ion pairs has been studied using the 1H NMR and LC-MS techniques. [ABSTRACT FROM AUTHOR]

Halogenated organic compounds (HOCs) pose a serious problem for the environment. Many are highly toxic and accumulate both in soil and in organisms. Their biological transformation takes place by dehalogenation, in which the halogen substituents are detached from the carbon in the organic compound by enzymes produced by microorganisms. This increases the compounds' water solubility and bioavailability, reduces toxicity, and allows the resulting compound to become more susceptible to biodegradation. The microbial halogen cycle in soil is an important part of global dehalogenation processes. The aim of the study was to examine the potential of microbial communities inhabiting natural and anthropogenically modified environments to carry out the dehalogenation process. The potential of microorganisms was assessed by analyzing the metagenomes from a natural environment (forest soils) and from environments subjected to anthropopression (agricultural soil and sludge from wastewater treatment plants). Thirteen genes encoding enzymes with dehalogenase activity were identified in the metagenomes of both environments, among which, 2-haloacid dehalogenase and catechol 2,3-dioxygenase were the most abundant genes. Comparative analysis, based on comparing taxonomy, identified genes, total halogens content and content of DDT derivatives, demonstrated the ability of microorganisms to transform HOCs in both environments, indicating the presence of these compounds in the environment for a long period of time and the adaptive need to develop mechanisms for their detoxification. Metagenome analyses and comparative analyses indicate the genetic potential of microorganisms of both environments to carry out dehalogenation processes, including dehalogenation of anthropogenic HOCs. [ABSTRACT FROM AUTHOR]

Dinuclear-gold-catalyzed radical difunctionalization of alkyl bromides with 1,7-enynes has been established via dehalogenation and 1,5-HAT processes. This protocol was used to construct, in a facile and efficient manner, a wide range of cyclopenta[c]quinolines bearing two quaternary carbon centers with good yields (28 examples, up to 84% yield). The good functional group compatibility and gram-scale preparation ability of the reaction proved its synthetic robustness. [ABSTRACT FROM AUTHOR]

The γ-radiolysis of 2-fluoroethanol-1, 2,2,2-trifluoroethanol-1, 3-fluoropropanol-1, and 4,4,4-trifluorobutanol-1 in aqueous solutions in an inert atmosphere or in the presence of oxygen has been studied. It has been found that the dehalogenation of hydroxyl-containing organic compounds is induced by •ОН and Н• radicals rather than hydrated electrons. The carbon-centered α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH are defluorinated much more efficiently than α-fluoroalkyl radicals, both vicinal (F–•CHCH2OH) and nonvicinal (F–•CHCH2CH2OH). In the absence of oxygen, α-fluoroalkyl radicals eliminate fluoride ions by the mechanism of nucleophilic substitution, and this process is enhanced in the presence of alkali. In an oxygenated medium, the dehalogenation of α-fluoroalkyl radicals occurs via the addition of oxygen molecules to them and the subsequent disproportionation of resulting peroxyl radicals. The dehalogenation of the α-hydroxy-β-fluoroethyl radicals FCH2–•CHOH is inhibited by oxygen through their oxidation. [ABSTRACT FROM AUTHOR]

The photophysical and photochemical reactivity of the organometallic mono(cyclooctatetraenide)-Ce(III) complexes: [(C8H8)Ce(μ-X)(THF)2]2 X = O3SCF3− (1), Cl− (2), were studied. In the course of these studies, a new polymorph of [(C8H8)Ce(μ-O3SCF3)(THF)2]2 (1) was described. Photoluminescence (PL) studies of 1 and 2 showed characteristic excitation and emission bands in the visible region, with bright green light emission under light irradiation from states corresponding to the 5d → 4f transition. Complexes 1 and 2 exhibit relatively long lifetime of 205.4 ± 0.2 and 145.8 ± 0.4 ns respectively. And the quantum yields (Φ) for 1 and 2 are 0.180 and 0.068 respectively. Electrochemical studies were performed on complexes 1 and 2 with a reversible Ce(III)/Ce(IV) redox couple recorded at E1/2 = −1.53 V versus the Fc/Fc+ for 2. Complex 1 shows an irreversible Ce(III / IV) oxidation wave. Complexes 1 and 2 revealed strongly-reducing, estimated, excited state reduction potentials of −3.31 and −4.02 V versus the Fc/Fc+ respectively, with small Stokes shifts of 0.12 eV. With their associated relatively long lifetimes, small Stokes shifts and large, negative values, both complexes were evaluated as potential photosensitisers for halogen atom transfer (XAT) using a test reaction of the dehalogenation of benzyl chloride. [ABSTRACT FROM AUTHOR]

(Hetero)aryl dehalogenation is a classical transformation usually performed using hydrogen gas and a metal supported on carbon, notably palladium (Pd/C). Though efficient, the need for a milder and operationally simple dehalogenation can arise. We found that the combination of Pd/C as catalyst and triethylsilane (TES) as hydrogen donor in THF resulted in a broadly applicable, easy to set up, and scalable debromination and deiodination. Optimization of the reaction showed that 1 mol% of Pd/C and 4 equiv of TES at room temperature were sufficient to obtain full conversion of most synthons of pharmaceutical interest in 4–24 h. The newly found conditions were applied to a large range of aromatic and heteroaromatic substrates, affording the desired targets in good to excellent yields with an exceptional functional group tolerance. [ABSTRACT FROM AUTHOR]

An ultrasound-assisted simple, easy and straightforward method for the synthesis of α-aminophosphonates has been developed via Kornblum/Kabachnik-fields reaction. The method involves in situ generation of an aldehyde intermediate from benzyl halides via oxidative dehalogenation followed by coupling with aryl amine and trialkyl phosphite in a one-pot three component manner under ultrasonic irradiations. The developed method is compatible with various functionalities and the desired products are obtained in good to excellent yield under mild conditions. [ABSTRACT FROM AUTHOR]

A series of 3,6-diamino-9-naphthylcarbazole derivatives were synthesized and characterized experimentally and computationally. As the lowest unoccupied molecular orbital of the naphthyl group has lower energy than that of the phenyl group, a charge transfer from carbazole to naphthyl in the excited states occurred causing solvatofluorochromism and solvent-dependency in fluorescence quantum yields. A molecule having two carbazole substituents sandwiching the central naphthyl ring had absorption reaching 470 nm and a high reducing capability in the excited state. This molecule could successfully photosensitize the hydrodehalogenation of haloarenes under visible light irradiation.

When 2‐iodobenzofuran was treated sequentially with lithium 2,2,6,6‐tetramethylpiperidide in tetrahydrofuran at −50 °C and an aldehyde, the 2‐substituted 3‐iodobenzofuran resulting from the halogen dance was the only isolated product. However, from 2‐iodobenzothiophene, these conditions led to mixtures in which the 2‐substituted 3‐iodobenzothiophene was always accompanied by the 2‐substituted benzothiophene. The use of 2‐bromobenzothiophene as a catalyst made it possible to significantly reduce this competitive dehalogenation. To confirm the halogen dance reaction, the products were unambiguously synthesized by using direct halogenations and deprotolithiation‐trapping sequences as key steps. Our efforts to access 2,7‐disubstituted and 7‐substituted derivatives of benzofuran and benzothiophene have also been reported. [ABSTRACT FROM AUTHOR]

Extracellular electron transfer materials (EETMs) in the environment, such as humic substances and biochar, are formed from the humification/heating of natural organic materials. However, the distribution of extracellular electron transfer (EET) functionality in fresh natural organic materials has not yet been explored. In the present study, we reveal the wide distribution of EET functionality in proteinaceous materials for the first time using an anaerobic pentachlorophenol dechlorinating consortium, whose activity depends on EETM. Out of 11 natural organic materials and 13 reference compounds, seven proteinaceous organic materials (albumin, beef, milk, pork, soybean, yolk, and bovine serum albumin) functioned as EETMs. Carbohydrates and lipids did not function as EETMs. Comparative spectroscopic analyses suggested that a β-sheet secondary structure was essential for proteins to function as EETMs, regardless of water solubility. A high content of reduced sulfur was potentially involved in EET functionality. Although proteinaceous materials have thus far been considered simply as nutrients, the wide distribution of EET functionality in these materials provides new insights into their impact on biogeochemical cycles. In addition, structural information on EET functionality can provide a scientific basis for the development of eco-friendly EETMs. [Display omitted] • Natural proteinaceous materials had extracellular electron transfer (EET) function. • The β-sheet secondary structure of proteins was crucial for the EET function. • A high content of reduced sulfur was potentially involved in the EET function. • Wide distribution of natural EET materials impacts biogeochemical cycling. • Structural information paves the synthetic study of eco-friendly EET materials. [ABSTRACT FROM AUTHOR]

The combination of chlorotrimethylsilane and NaI is disclosed as a reducing system for protodehalogenation of benzothiazole and thiazole derivatives; surprisingly, the alkoxy groups present in the system are unaffected. The optimized reaction conditions tolerate various functional groups and display good efficiency in the regioselective protodehalogenation of a variety of benzothiazole and thiazole derivatives. In addition, the potential application of the protocol was examined by comparing it with previously developed methods; in most of the cases, the present strategy resulted in better yields under milder condition. The mechanistic studies suggest that the reaction probably proceeds through a radical pathway. [ABSTRACT FROM AUTHOR]

By a combination of scanning tunneling microscopy imaging and density functional theory calculations, dehalogenation processes of symmetric polyhalogenated benzenes were explored on Ag(111), and a series of intermediate states were captured and visualized in real space. These results reveal a sequential dehalogenation scenario of symmetric polybrominated aromatics, which will broaden the understanding of on-surface dehalogenation reactions. [ABSTRACT FROM AUTHOR]

Herein, a novel strategy to construct artificial light‐harvesting systems (LHSs) based on micelles is proposed. Two efficient artificial LHSs are fabricated in water based on tetraphenylethene (TPE) modified surfactants (TPE‐SAA). TPE‐SAA can self‐assemble into spherical micelles in an aqueous solution through noncovalent interactions. Due to the aggregation‐induced emission effect of the TPE unit, TPE‐SAA micelles exhibit strong emission and directly act as donors to achieve the energy transfer process. Firstly, two fluorescent dyes (4,7‐bis(thien‐2‐yl)‐2,1,3‐benzothiadiazole (DBT) and amphoteric sulforhodamine 101 (SR101)), which are localized in the hydrophobic interior and positively charged surface of TPE‐SAA respectively, are chosen as energy acceptors to realize the two‐step sequential energy transfer process with high efficiency. In addition, energy transfer can also take place from TPE‐SAA to SR101, and bright white‐light emission with a CIE coordinate of (0.31, 0.33) can be achieved by adjusting the ratio of donor to acceptor. Furthermore, to utilize the harvested energy, the micelle‐based artificial LHSs are employed to promote the aerobic cross‐dehydrogenative coupling reaction. Moreover, the dehalogenation reaction of α‐bromoacetophenone can also be catalyzed by the TPE‐SAA+DBT+SR101 system in water. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of battery-type anode limits the realization of high capacitance especially at elevated charge-discharge rates for lithium-ion capacitors (LICs). In this work, graphene wrapped carbon cages (G x P y) are obtained via a facile physical-confined pyrolysis approach from graphene oxide (GO)/polyvinylidene fluoride (PVDF), which exhibits great promise as a fast and large-capacity anode for LICs. The thermal degradation process analysis reveals that carbon cages with abundant mesopores derived from the dehalogenation of PVDF are formed spontaneously due to the HF releasing in the pyrolysis process with the aid of physical confined GO template. Hollow carbon cages could ameliorate the Li+ transport path, while 2D graphene serves as a conducting bridge connecting the isolated carbon cages to minimize the barrier of charge transfer. As a result, a LIC pouch-cell based on G x P y hierarchical carbon anode demonstrates high energy density and superior power density, as well as remarkable cycle life. This study may open a unique avenue for designing fast and large-capacity carbon anode and push the development of high-performance LICs. We report a physical-confined pyrolysis pathway to prepare hierarchical carbon anode composed of graphene wrapped carbon cages. Carbon cage structure can ameliorate the Li+ transport path, while graphene serves as a conducting bridge connecting the isolated carbon cages, resulting fast kinetics and large capacity as anode material. As a result, a LIC pouch-cell based on G x P y hierarchical carbon anode demonstrates impressive electrochemical performance. [Display omitted] • A physical-confined pyrolysis pathway is developed to prepare hierarchical carbon anode composed of graphene wrapped carbon cages. • The thermal degradation mechanism reveals that carbon cages are derived from the dehalogenation of PVDF due to the HF releasing in the pyrolysis process. • Cage structure can ameliorate Li + transport path, resulting fast kinetics and large capacity as anode material. [ABSTRACT FROM AUTHOR]