Journal of Fluorine Chemistry最新文献

The research on SF₆ degradation and conversion is of great significance for environmental protection. Based on the density functional theory, the adsorption process of SF₆ on the TiO₂(001) and TiO₂(101) surfaces was investigated. The results indicate a strong interaction between SF₆ and the TiO₂ surface. Significant structural changes in the SF₆, such as elongation of the S-F bonds, were observed after adsorption, rendering the SF₆ more prone to decomposition. According to Mulliken charge analysis, electron transfer occurs from the TiO₂ surface to the SF₆, revealing SF₆ as an electron acceptor while TiO₂ acts as an electron donor. Analysis of the density of states confirms a pronounced electronic orbital overlap between the S/F atoms of SF₆ and the Ti/O atoms of TiO₂, and the charge density distribution along the Z-axis further supports this charge transfer process. Additionally, experimental studies have demonstrated that TiO₂ photocatalysis can accelerate the degradation of SF₆ during DBD. This study demonstrates the catalytic potential of TiO₂ in the degradation of SF₆ insulating gas and provides theoretical support for the efficient and harmless treatment of SF₆.

The interaction of tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato)europium(III), (Eu(FOD)₃), with xenon difluoride in acetonitrile solution was found to be accompanied by chemiluminescence (CL). The kinetic curve of CL at a ratio of reagents Eu³⁺/XeF₂ of 1:2 has a complex form; an initial rapid decrease is replaced by an increase in CL intensity, the maximum of which is reached approximately 10 min after the start of the reaction. Next, an exponential decay of the CL intensity is observed over several tens of minutes. The CL spectrum is located in the wavelength range 400–750 nm and corresponds to the emission of an electronically excited europium (III) ion coordinated with FOD and fluoride ion. Spectral methods were used to identify the reaction products – europium (III) fluoride in the sediment and oxygen difluoride in the gas phase. A mechanism for chemiexcitation of europium(III) has been proposed, including: 1) acceptance of fluorine anion from the XeF₂ molecule by europium ion with the formation of active intermediate XeF⁺; 2) oxidative fluorination of the ligand, which is initiated by the interaction of oxygen atom of the FOD ligand with XeF⁺ cation and ends with the formation of oxygen difluoride and the electronically excited product P*, presumably a fluorinated ketone; 3) non-radiative transfer of excitation energy from P* to the europium ion within its coordination sphere, followed by its radiative deactivation.

The carbon residue is a hazardous waste generated by the aluminum electrolysis production process, which contains a large amount of electrolyte fluoride salts. In order to recover the electrolyte components in carbon residue, this paper proposes a new method of using carbon residue to prepare aluminum fluoride by converting Na₅Al₃F₁₄ and Na₃AlF₆ in carbon residue into aluminum fluoride to realize the recycling of fluoride in carbon residue. In the initial step, optimal parameters for carbon removal during roasting have been determined, including an oxygen flow rate of 7 g/min, a roasting temperature of 670 °C, and a roasting time of 80 min. The roasted clinker is obtained, and the removal rate of carbon reaches 99.95 % while the loss rate of fluorine is 0.48 %. In the second step, the mix anhydrous Al₂(SO₄)₃ with roasted clinker for roasting. The optimal roasting temperature of 670 °C, the time of 10 min, and the mass ratio of anhydrous Al₂(SO₄)₃ to roasted clinker of 5:5 could convert fluoride to AlF₃ products, with a conversion rate of 99.76 % and a loss rate of fluorine of 1.05 %. Finally, by removing sulfate impurities through water leaching for 15 min at 35 °C and with a liquid-solid ratio of 6 ml/g, the loss rate of fluorine is 3.98 %. This process yields AlF₃ with a purity of 94.30 %. The recovery rate of fluorine in the whole process is 94.56 %, which successfully achieves the recycling of fluorine in the carbon residue to obtain AlF₃ products.

NaLuF₄:Yb³⁺,Er³⁺ micrometer prismatic crystals are potential materials for the preparation of optical waveguide devices. However, structural defects and OH^– groups are generated inside and on their surfaces during growth processes. The structural defects and OH^– groups lead to a large depletion of excitation energy and severely quench the downconversion luminescence of Er³⁺. In addition, the Yb³⁺/Er³⁺ co-doping ratio significantly affects the downconversion luminescence of the microcrystals, which in turn affects the performance of the optical waveguide amplifiers based on the microcrystals. By adjusting the co-doping ratio of Yb³⁺ and Er³⁺ in the microcrystals and removing the defects in the crystals, their downconversion luminescence performance was significantly improved. The results showed that the downconversion luminescence under the excitation from a 980 nm laser reached the maximum value when the doping ratio of Yb³⁺ and Er³⁺ was 20:1.5. In addition, the OH^– groups and structural defects in the micrometer crystals were significantly eliminated by ion-exchange and high-temperature annealing treatments, and the crystalline quality was significantly improved. After ion-exchange and high-temperature annealing treatments, the downconversion luminescence enhancement of NaLuF₄:Yb³⁺,Er³⁺ microcrystals was 2.5 times that of the untreated samples.

An interesting product divergence in the reaction of trifluorodiazoethane with arylidene-1,3-indanediones is reported. The reaction conducted using 10 mol% of silver carbonate afforded trifluoromethylspiropyrazolines, while with excess of cesium fluoride in methanol, the cycloaddition was followed by nucleophilic ring opening of the spiropyrazoline to afford trifluoromethylated o-carbomethoxybenzoylpyrazolines. Both protocols work under mild reaction conditions and exhibit good functional group tolerance.

The current investigation evaluated the in vitro bioefficacy of a newly synthesized unsymmetrical imidazolium salt [1-(2,6-diisopropylphenyl)-3-(2-fluoro-benzyl)-1H-imidazol-3-ium bromide] that contains the electron-withdrawing fluorine atom at the ortho position against agriculturally significant phytopathogens. The molecular structure of the imidazolium salt was characterized by various spectroscopic techniques such as ¹H, ¹³C, and ¹⁹F NMR, FTIR, and high-resolution mass spectrometry (HRMS). Antimicrobial bioassay of the compound has been tested against two Gram-negative, bacterial phytopathogens namely Ralstonia solanacearum (Rs) (Gen Bank accession no. OQ743450) [causal agent: bacterial wilt of solanaceous crops], and Xanthomonas citri pv. citri (Xcc) (Gen Bank accession no. OR7036310) [causal agent: citrus canker in citrus trees] and two fungal phytopathogens namely Fusarium solani (Gen Bank accession no. OR140825) [causal agent: Fusarium die-back in tea] and Pseudopestalotiopsis chinensis (Gen Bank accession no. OR140826) [causal agent: grey blight in tea]. Different concentrations of imidazolium salt was tested against the target phytopathogens using the in vitro antimicrobial bioassay through disc diffusion method. The imidazolium salt demonstrated a maximum percentage inhibition of 16.70 and 21.78 against the bacterial phytopathogens R. solanacearum, and X. citri pv. citri, respectively, at a concentration of 2000 ppm over negative control. Similarly, the compound demonstrated promising antagonism against the tea fungal pathogens F. solani and P. chinensis (percentage inhibition up to 61.43 and 80.84, respectively at 2000 ppm) over negative control. Five replications were maintained in each of the cases. The present investigation demonstrated the potential of fluorinated imidazolium salt as commercial antimicrobial agent in integrated disease management schedule to control significant phytopathogenesis in agriculture including in tea.

Decarboxylative transformations are valuable tools for carbon-heteroatom bond formation. However, synthetic applications of the decarboxylation of aromatic carboxylic acids to produce C(sp²)–F bonds remain limited. Herein, we propose a tandem catalytic decarboxylation/fluorination of N-acetylanthranilic acids to produce useful organofluorine compounds by using Ir(I)/bisphosphine complexes.

Molten salt reactor uses LiF-BeF₂-ZrF₄ (FLiBeZr) as the solvent, and UF₄ is dissolved in homogeneous FLiBeZr to form liquid fuel salt (FLiBeZrU). However, a second phase ZrO₂ precipitate usually forms during the preparation of FLiBeZr solvent. In this paper, the formation mechanism of ZrO₂, its dissolution equilibrium in FLiBeZr and its effect on the physical properties of molten salts were studied. Then, anhydrous HF-H₂ gas was introduced as a deoxidizer to react with the dissolved oxide and ZrO₂. By optimizing the H₂HF tube bubbling at the bottom, even with the addition of UF₄, a uniform FLiBeZr with a total oxygen content of 120 ppm can be prepared without the production of UO₂.