Carbon nanofibres fluorinated using TbF4 as fluorinating agent. Part I: Structural properties

Fluorination of carbon nanofibres (CNFs) under fluorine gas at 480 °C leads to high fluorine content but also to some partial exfoliation. In order to avoid such phenomenon, an alternative route has been performed at temperatures ranged between 420 and 500 °C using a fluorinating agent, i.e. terbium tetrafluoride. The structural properties of the fluorinated CNFs are discussed taking into account the data of ¹³C solid state NMR, Raman spectroscopy, SEM, TEM and XRD. Whatever the fluorination temperature, a fluorinated phase of (CF)_n structural type, is formed contrary to the direct process using F₂ gas for which a (C₂F)_n-type fluorinated phase appeared for fluorination temperatures lower than 450 °C. The progressive release of fluorine atoms from the thermal decomposition of TbF₄ allows an homogenous distribution of the fluorinated part into the CNFs matrix and the formation of a unique (CF)_n type structure. Moreover, for high fluorination temperatures (480 and 500 °C), the fluorination leads to some nanofibres breaking but in no way to exfoliation.     

Direct fluorination of the polyimide matrimid® 5218: The formation kinetics and physicochemical properties of the fluorinated layers

Fluorinated polymers have a set of unique properties, including improved chemical stability and thermal stability and good barrier and membrane parameters, which are mainly defined by their surface properties. This article presents systematic data on the direct fluorination of the polyimide Matrimid® 5218, a commercially available polymer suitable for the formation of gas‐separation hollow fibers. Changing the fluorination conditions (i.e., the fluorinated mixture composition, fluorine partial pressure, and treatment duration) allows the rate of formation of the surface‐fluorinated layer over the 0.1–10 μm range to be kept under control. The physicochemical properties of modified layers (i.e., the chemical composition, formation of radicals, refractive index, IR and UV spectra, density, and surface energy) are examined. The thickness of the fluorinated layer (δ_F) depends on the fluorination duration (t): δ_F ～ t^0.5. During fluorination, hydrogen atoms are replaced with fluorine, double bonds are saturated with fluorine, and at least one CN bond in the five‐member ring is disrupted. Fluorination results in a significant increase in the polymer density, transparency in the visible and ultraviolet regions of spectra, and a reduction of the refractive index. A high concentration of long‐living radicals (up to ～5 × 10¹⁹ radicals/cm³ of the fluorinated layer) is generated under fluorination. This can be used for subsequent grafting (e.g., with acrylonitrile). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 6–17, 2004     

Thermal treatment of fluorinated graphene: An in situ Raman spectroscopy study

Fluorinated graphene is a promising material for electronic applications, and its thermal properties are of high importance. Here, the resilience of fluorinated graphene to a range of temperatures is presented. The heating/cooling cycles were carried out on fluorinated monolayer, fluorinated bilayer graphene and non-fluorinated graphene as well, for comparison. In order to follow the changes of the properties of the material, in situ Raman spectra were acquired at different temperature steps. The results show that most of fluorine bonded to graphene can be removed at unusually mild temperatures, but not completely, as some fluorine can still be traced even upon heating at 800 K. Additionally, despite monolayer graphene has a higher level of fluorination than bilayer graphene, after the first heating/cooling cycle a similar amount of fluorine is found on both fluorinated graphene samples.     

The effect of nanostructure on the thermal properties of fluorinated carbon nanofibres

Using thermogravimetic analysis in air, the thermal properties of fluorinated carbon nanofibres have been investigated. The fluorination level, the C–F bonding, the number of structural defects and the distribution of fluorine atoms in the carbon matrix have been modified using three fluorination routes, (i) a direct process using a flux of pure molecular fluorine F₂ (dynamic process), (ii) a filling of a closed reactor by this reactive gas (static process) and (iii) controlled fluorination using the thermal decomposition of a solid fluorinating agent TbF₄. At given fluorine contents, only the location of the fluorine atoms within the nanofibre changes the thermal stability, which can be increased up to 480 °C; such improvement is obtained when the fluorinated regions are located in the outer shell (tubes).     

Fluorination of pressure-polymerized C60 phases

The reactivity of O-, T- and R-phases of the high pressure-high temperature (HPHT) polymerized C₆₀ towards gaseous fluorine in the temperature range of 50-250 °C was investigated. The reaction products were characterized by FTIR, powder X-ray diffraction, SEM, EDX, and VTP-EIMS to determine the bulk stoichiometries, bonding patterns, phase compositions, crystalline structures and thermal decomposition behavior of the fluorinated polymers. At 1 h isothermal treatment duration, fluorinated products with various bulk stoichiometries were obtained from different polymer phases with the R-phase showing the highest fluorine uptake. At 250 °C, all C₆₀ polymers showed partial decomposition to unfluorinated C₆₀ monomer under fluorine atmosphere. At 200 °C, the fluorination of R-phase yielded a pure fluoropolymer most likely having a {C₆₀F_x}_n (x = 36-44) composition. The same fluoropolymer was presumably obtained from O- and T-phases in lower yields. The linear chain structure was suggested for this new fluorocarbon polymer in agreement with the molecular mechanics modeling calculations.     

Development of Fragment‐Based n‐FABS NMR Screening Applied to the Membrane Enzyme FAAH

Despite the recognized importance of membrane proteins as pharmaceutical targets, the reliable identification of fragment hits that are able to bind these proteins is still a major challenge. Among different ¹⁹F NMR spectroscopic methods, n‐fluorine atoms for biochemical screening (n‐FABS) is a highly sensitive technique that has been used efficiently for fragment screening, but its application for membrane enzymes has not been reported yet. Herein, we present the first successful application of n‐FABS to the discovery of novel fragment hits, targeting the membrane‐bound enzyme fatty acid amide hydrolase (FAAH), using a library of fluorinated fragments generated based on the different local environment of fluorine concept. The use of the recombinant fusion protein MBP‐FAAH and the design of compound 11 as a suitable novel fluorinated substrate analogue allowed n‐FABS screening to be efficiently performed using a very small amount of enzyme. Notably, we have identified 19 novel fragment hits that inhibit FAAH with a median effective concentration (IC₅₀) in the low mM –μM range. To the best of our knowledge, these results represent the first application of a ¹⁹F NMR fragment‐based functional assay to a membrane protein.     

Graphene nanochains and nanoislands in the layers of room-temperature fluorinated graphite

Intercalated compound of graphite fluoride with n-heptane has been synthesized at room temperature using a multi-stage process including fluorination by a gaseous BrF₃ and a set of intercalant exchange reactions. It was found that composition of the compound is CF_0.40(C₇H₁₆)_0.04 and the guest molecules interact with the graphite fluoride layers through the van der Waals forces. Since the distance between the filled layers is 1.04 nm and the unfilled layers are separated by ∼0.60 nm, the obtained compound can be considered as a stack of the fluorinated graphenes. These fluorinated graphenes are large in area making it possible to study local destruction of the π conjugated system on the basal plane. It was shown that fluorine atoms form short chains, while non-fluorinated sp² carbon atoms are organized in very narrow ribbons and aromatic areas with a size smaller than 3 nm. These π electron nanochains and nanoislands preserved after the fluorination process are likely responsible for the value of the energy gap of the compound of ∼2.5 eV. Variation in the size and the shape of π electron regions within the fluorinated graphene layers could be a way for tuning the electronic and optical characteristics of the graphene-based materials.     

Electrochemical performance of low temperature fluorinated graphites used as cathode in primary lithium batteries

The present study highlights the electrochemical performance of two series of fluorinated graphites used as the cathode in primary lithium batteries. These compounds were prepared under fluorine gas at room temperature using a catalytic atmosphere made of boron or chlorine fluoride, and then thermally treated between 100 and 600 °C. The electrochemical properties are correlated to a complete physico-chemical characterization, already performed by XRD, NMR, FT-IR and EPR. In particular, important parameters are taken into account: C-F bonding, carbon hybridization, fluorine content (i.e. F/C ratio) and amount of intercalated catalyst residues. It is shown that the average discharge potential of fluorinated graphite used in primary lithium batteries can be predicted owing to the chemical shift values (δ_C-F) obtained by solid ¹³C NMR. On the other hand, the higher capacity values are achieved for low temperature fluorinated graphite treated at the highest temperatures, i.e. for high fluorination level. The electrochemical performance study of these materials is completed by the study of the effect of simulated storage. The differences between the various samples during electrochemical tests and those observed using different electrolytes are discussed. Fluorinated graphites obtained with a chlorine catalyst or post-treated at temperatures higher than 450 °C are unaffected by ageing.     

Discharge characteristics of graphite fluorides prepared via graphite intercalation compounds in nonaqueous lithium cells

Two types of graphite fluorides (C₂F)_n and (CF)_n were prepared by refluorination of thermally decomposed ionic graphite intercalation compounds of fluorine. Discharge behavior and effect of the heat treatment of graphite fluoride were investigated. This method drastically decreased the reaction time compared with the direct fluorination of graphite. OCV of (C₂F)_n was higher by 0.3 V than that of the conventionally prepared one, however, overpotential was the same at the constant current density of 0.5 mA cm⁻². On the other hand, the same OCV and less overpotential by 0.3 V were observed for (CF)_n. The heat treatment of these samples in fluorine atmosphere at higher temperatures increased the discharge capacity and provided a more flat discharge potential.     

Targeted Fluorination of a Nonsteroidal Anti‐inflammatory Drug to Prolong Metabolic Half‐Life

In drug design, one way of improving metabolic stability is to introduce fluorine at a metabolically labile site. In the early stages of drug design, identification of such sites is challenging, and a rapid method of assessing the effect of fluorination on a putative drug’s metabolic stability would be of clear benefit. One approach to this is to employ micro‐organisms that are established as models of drug metabolism in parallel with the synthesis of fluorinated drug analogues. In this study, we have used the filamentous fungus Cunninghamella elegans to identify the metabolically labile site of the nonsteroidal anti‐inflammatory drug flurbiprofen, to aid in the design of fluorinated derivatives that were subsequently synthesised. The effect of the additional fluorine substitution on cytochrome P450‐catalysed oxidation was then determined via incubation with the fungus, and demonstrated that fluorine substitution at the 4′‐position rendered the drug inactive to oxidative transformation, whereas substitution of fluorine at either 2′ or 3′ resulted in slower oxidation compared to the original drug. This approach to modulating the metabolic stability of a drug‐like compound is widely applicable and can be used to address metabolic issues of otherwise good lead compounds in drug development.     

氟气氟化含氢氟聚醚制备双端官能团全氟聚醚

以含氢氟聚醚（E10H）为原料，利用氟氮混合气进行氟化制备了双端羟基全氟聚醚（F-E10H-AL），分别探索了常温氟化、低温氟化及先低温后常温氟化的3种氟化工艺。然后与双三氟甲烷磺酸亚胺锂（LiTFSI）制备成锂离子电解质。采用红外光谱、核磁氢谱和氟谱分析氟化后的产物结构，并采用电化学工作站测试了阻抗和计时电流。结果表明，低温氟化工艺具有较高的氟化效率，在-10℃对E10H直接氟化12h后，分子链上有21.0%的H被F取代，但是产生较多的封端基团CF3O-。当利用六氟环氧丙烷二聚体酯化保护E10H上的羟基时，采用先低温后常温氟化工艺，分子链上有48.3%的H被F取代。最后将氟化产物还原，得到F-E10H-AL，分子链末端基本没有CF3O-，含量为0.7%。结合阻抗和计时电流的数据，计算出F-E10H-AL/LiTFSI的离子迁移数为0.32，高于PFPE-OH/LiTFSI（0.07）。     

SWATH Based Quantitative Proteomics Reveals Significant Lipid Metabolism in Early Myopic Guinea Pig Retina

Most of the previous myopic animal studies employed a single-candidate approach and lower resolution proteomics approaches that were difficult to detect minor changes, and generated limited systems-wide biological information. Hence, a complete picture of molecular events in the retina involving myopic development is lacking. Here, to investigate comprehensive retinal protein alternations and underlying molecular events in the early myopic stage, we performed a data-independent Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH) based proteomic analysis coupled with different bioinformatics tools in pigmented guinea pigs after 4-day lens-induced myopia (LIM). Myopic eyes compared to untreated contralateral control eyes caused significant changes in refractive error and choroid thickness (p < 0.05, n = 5). Relative elongation of axial length and the vitreous chamber depth were also observed. Using pooled samples from all individuals (n = 10) to build a species-specific retinal ion library for SWATH analysis, 3202 non-redundant proteins (with 24,616 peptides) were identified at 1% global FDR. For quantitative analysis, the 10 individual retinal samples (5 pairs) were analyzed using a high resolution Triple-TOF 6600 mass spectrometry (MS) with technical replicates. In total, 37 up-regulated and 21 down-regulated proteins were found significantly changed after LIM treatment (log2 ratio (T/C) > 0.26 or < −0.26; p ≤ 0.05). Data are accepted via ProteomeXchange with identifier PXD025003. Through Ingenuity Pathways Analysis (IPA), “lipid metabolism” was found as the top function associated with the differentially expressed proteins. Based on the protein abundance and peptide sequences, expression patterns of two regulated proteins (SLC6A6 and PTGES2) identified in this pathway were further successfully validated with high confidence (p < 0.05) using a novel Multiple Reaction Monitoring (MRM) assay on a QTRAP 6500+ MS. In summary, through an integrated discovery and targeted proteomic approach, this study serves as the first report to detect and confirm novel retinal protein changes and significant biological functions in the early LIM mammalian guinea pigs. The study provides new workflow and insights for further research to myopia control.     

Characterization of New Proteomic Biomarker Candidates in Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis type IVA (MPS IVA) is a lysosomal storage disease caused by mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Skeletal dysplasia and the related clinical features of MPS IVA are caused by disruption of the cartilage and its extracellular matrix, leading to a growth imbalance. Enzyme replacement therapy (ERT) with recombinant human GALNS has yielded positive results in activity of daily living and endurance tests. However, no data have demonstrated improvements in bone lesions and bone grow thin MPS IVA after ERT, and there is no correlation between therapeutic efficacy and urine levels of keratan sulfate, which accumulates in MPS IVA patients. Using qualitative and quantitative proteomics approaches, we analyzed leukocyte samples from healthy controls (n = 6) and from untreated (n = 5) and ERT-treated (n = 8, sampled before and after treatment) MPS IVA patients to identify potential biomarkers of disease. Out of 690 proteins identified in leukocytes, we selected a group of proteins that were dysregulated in MPS IVA patients with ERT. From these, we identified four potential protein biomarkers, all of which may influence bone and cartilage metabolism: lactotransferrin, coronin 1A, neutral alpha-glucosidase AB, and vitronectin. Further studies of cartilage and bone alterations in MPS IVA will be required to verify the validity of these proteins as potential biomarkers of MPS IVA.     

PVC树脂氟化后的加工性能及热稳定性

采用氟气通过PVC树脂层,制得PVC树脂颗粒表面氟化的PVC树脂,研究了氟气流量、通氟气时间、氟气含量对PVC干混料熔融因数F的影响,通氟气时间对PVC干混料热稳定时间的影响,并展望了氟化PVC树脂的应用前景。试验得出的最佳氟化反应条件为:V(N2)∶V(F2)=9∶1,氟气流量为15 mL/min,通氟气时间为4 h;制得的氟化PVC干混料的熔融因数F提高了18%,热稳定时间提高了23%。     

Effect of the fluorine-addition order on the hydrodesulfurization activity of fluorinated NiW/Al2O3 catalysts

Fluorinated NiW/Al₂O₃ catalysts with different orders of fluorine addition have been prepared, tested for hydrodesulfurization (HDS) of thiophene, and characterized using nitric oxide chemisorption and temperature-programmed sulfidation. The catalyst surface area has been affected by fluorine addition but not by the order of fluorination. The fluorine addition-order does not affect the amount of fluorine retained in the catalysts after the calcination and the reaction steps, either. On the other hand, the order of fluorine addition changes the dispersion of the nickel and the tungsten species, incorporation of nickel with the tungsten edge sites, and consequently the HDS activity of the catalysts. The catalyst fluorinated in the last step, i.e., after addition of both tungsten and nickel, shows the highest activity in thiophene HDS, which is supported by other experimental results indicating the most nitric oxide chemisorption and the largest incorporation of nickel with the tungsten species. Accordingly, enhancement of the catalyst activity by fluorination is due to the repartition of the metal species rather than to partial solubilization of alumina in the fluorine-addition step.     

Detection of Serum Protein Biomarkers for the Diagnosis and Staging of Hepatoblastoma

The present study aimed to identify serum biomarkers for the detection of hepatoblastoma (HB). Serum samples were collected from 71 HB patients (stage I, n = 19; stage II, n = 19, stage III, n = 19; and stage IV, n = 14) and 23 age- and sex-matched healthy children. Differential expression of serum protein markers were screened using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS), and the target proteins were isolated and purified using HPLC and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), SEQUEST, and bioinformatics analysis. Differential protein expression was confirmed by enzyme-linked immunosorbent analysis (ELISA). SELDI-TOF-MS screening identified a differentially expressed protein with an m/z of 9348 Da, which was subsequently identified as Apo A–I; its expression was significantly lower in the HB group as compared to the normal control group (1546.67 ± 757.81 vs. 3359.21 ± 999.36, respectively; p < 0.01). Although the expression level decreased with increasing disease stage, pair-wise comparison revealed significant differences in Apo A–I expression between the normal group and the HB subgroups (p < 0.01). ELISA verified the reduced expression of Apo A–I in the HB group. Taken together, these results suggest that Apo A–I may represent a serum protein biomarker of HB. Further studies will assess the value of using Apo A–I expression for HB diagnosis and staging.     

Direct fluorination of various poly(p-phenylene): Effects of the polymer synthesis and thermal post-treatment

In order to complete a preliminary work about the direct fluorination of poly(p-phenylene) (PPP), the main parameters of the process were investigated. The molecular (chain length and crystallinity) and morphological effects (B.E.T. surface, granulometry) were studied. So, two new starting samples were studied in addition to PPP synthesized by the Kovacic's method (i) a commercial PPP (Polysciences) and (ii) a pyrolyzed PPP, which is similar to an amorphous hydrogenated carbon. Moreover, an annealed PPP (Kovacic's synthesis and post-treatment at 400 °C for 36 h) was compared to the as-synthesized polymer. The reactions with F₂ gas differ significantly in accordance with the synthesis way and the post-treatment (annealing or pyrolysis). Investigations about the direct fluorination of PPPs were carried out for a better understanding of their behavior with respect to molecular fluorine. An extensive characterization was performed by complementary techniques (¹⁹F and ¹³C NMR, FT-IR, and EPR). The fluorine content in the fluorinated PPPs is evaluated by these methods and a reaction mechanism is proposed.     

Carbon nanofibres fluorinated using TbF4 as fluorinating agent. Part II: Adsorption and electrochemical properties

The adsorption and electrochemical properties of the carbon nanofibres fluorinated using TbF₄ as fluorinating agent have been investigated by nitrogen measurements and galvanostatic discharge in primary lithium batteries, respectively. These properties are compared to those obtained for carbon nanofibres fluorinated by pure fluorine gas (direct fluorination). The amount of structural defects, the formed structural phase and the possible partial exfoliation have been investigated in order to understand the properties difference for the CNFs fluorinated by the two routes. Higher amounts of both dangling bonds and CF₂, CF₃ groups were registered by EPR and ¹⁹F NMR for CNFs fluorinated by direct route. Moreover, SEM study underlines the partial exfoliation, which occurred only during the direct fluorination at 480 °C. As a consequence, CNFs fluorinated by TbF₄ develop the highest faradic yield for a use in primary lithium battery.     

Alkylation of Benzene with Long-Chain Olefins Catalyzed by Fluorinated β Zeolite

The effects of fluorination on H zeolite and alkylation of benzene with long-chain olefins catalyzed by fluorinated zeolite are investigated. The lifetime of the catalysts depends on the surface area and pore volume rather than acidity. When the fluorine content is 0.5%, the lifetime improves by 30%, when the catalyst has maximum specific surface area and pore volume.     

三乙胺三氟化氢在含氟脂肪族化合物合成中的应用

三乙胺三氟化氢作为一种向化合物分子中引入氟原子的有效氟化试剂,具有较小的腐蚀性、温和的反应活性以及良好的区域选择性,在含氟化合物的合成中有着广泛的应用。综述了三乙胺三氟化氢在含氟脂肪族化合物合成中的应用,重点介绍采用亲核氟化、亲电氟化、环氧开环氟化和电化学氟化进行的反应。