Fluorine-containing Compounds Research Articles

A Review of Fluoride Removal from Phosphorous Gypsum: A Quantitative Analysis via a Machine Learning Approach.

This review comprehensively explores fluoride removal from phosphogypsum, focusing on its composition, fluorine-containing compounds, characterization methods, and defluorination techniques. It initially outlines the elemental composition of phosphogypsum prevalent in major production regions and infers the presence of fluorine compounds based on these constituents. The study highlights X-ray photoelectron spectroscopy (XPS) as a pivotal method for characterizing fluorine compounds, emphasizing its capability to determine precise binding energies essential for identifying various fluorine species. Additionally, the first-principle density functional theory (DFT) is employed to estimate binding energies of different fluorine-containing compounds. Significant correlations are observed between the total atomic energy of binary fluorides (e.g., of alkali metals, earth metals, and boron group metals) and XPS binding energies. However, for complex compounds like calcium fluorophosphate, correlations with the calculated average atomic total energy are less direct. The review categorizes defluorination methods applied to phosphogypsum as physical, chemical, thermal, and thermal-combined processes, respectively. It introduces neural network machine learning (ML) technology to quantitatively analyze and optimize reported defluorination strategies. Simulation results indicate potential optimizations based on quantitative analyses of process conditions reported in the literature. This review provides a systematic approach to understanding the phosphogypsum composition, fluorine speciation, analytical methodologies, and effective defluorination strategies. The attempts of adopting DFT simulation and quantitative analysis using ML in optimization underscore its potential and feasibility in advancing the industrial phosphogypsum defluorination process.

Reasons why life on Earth rarely makes fluorine-containing compounds and their implications for the search for life beyond Earth

Life on Earth is known to rarely make fluorinated carbon compounds, as compared to other halocarbons. We quantify this rarity, based on our exhaustive natural products database curated from available literature. We build on explanations for the scarcity of fluorine chemistry in life on Earth, namely that the exclusion of the C–F bond stems from the unique physico-chemical properties of fluorine, predominantly its extreme electronegativity and strong hydration shell. We further show that the C–F bond is very hard to synthesize and when it is made by life its potential biological functions can be readily provided by alternative functional groups that are much less costly to incorporate into existing biochemistry. As a result, the overall evolutionary cost-to-benefit balance of incorporation of the C–F bond into the chemical repertoire of life is not favorable. We argue that the limitations of organofluorine chemistry are likely universal in that they do not exclusively apply to specifics of Earth’s biochemistry. C–F bonds, therefore, will be rare in life beyond Earth no matter its chemical makeup.

Chitin-augmented wetting resistance and water-in-oil emulsion separation performance of silane-modified polyketone membrane

The utilization of membrane technology for separating water-in-oil (W/O) emulsions necessitates a membrane possessing high hydrophobic properties. However, the use of naturally hydrophobic membrane materials, such as polyvinylidene fluoride, is undesirable due to the persistence of fluorine-containing compounds in the environment. Polyketone (PK) membranes present a potential alternative, but their inherent hydrophilic properties can hinder the W/O emulsion separation process. To address this issue, hydrophobic modification of PK membranes can improve their performance in separating W/O emulsion. Natural hydrophobic materials like chitin offer a more sustainable alternative compared to synthetic materials. Chitin was introduced onto the membrane surface along with hexadecyltrimethoxysilane (HDTMS) subsequent to the initial reaction of the PK membrane with tetraethyl orthosilicate (TEOS). Comparative analysis revealed that the mixed chitin and HDTMS modification resulted in the lowest surface wettability compared to membrane modification using only TEOS, HDTMS, and chitin. Examination of membrane performance through toluene emulsion separation demonstrated increased permeability after modification, with permeate toluene purity over 99.8%. Additionally, the chitin and silane-modified PK membrane exhibited a two-fold increase in filtration process permeability, indicating outstanding fouling resistance. These findings underscore the potential of natural compounds in imparting desired hydrophobic properties to membranes while minimizing reliance on synthetic materials.

Rhodium(III)-Catalyzed Annulation Synthesis of Difluorinated Quinazolinone Derivatives Using an Amide Carbonyl as the Directing Group.

The use of amide carbonyl groups of substrates as weakly coordinating directing groups has received a significant amount of attention. Recently, difluoromethylene alkynes have been successfully used in fluorination reactions, resulting in the preparation of various fluorine-containing compounds. This work describes a [4+2] annulation method for creating a range of fluorinated quinolino[2,1-b]quinazolinone derivatives. The derivatives are formed through Rh(III)-catalyzed cascade cyclization of 3-phenylquinazolinones and gem-difluoromethylene alkynes.

Effect of surface composition on the stability of Ti- and V-based oxycarbide and oxynitride MXenes

Oxycarbide MXenes were recently experimentally identified, opening up the possibility of a vast majority of carbon-based MXenes synthesised to date being in fact oxycarbides, wherein some substitutional oxygen atoms are present amid the layers that were previously thought to contain carbon only. Here, using an approach based on density-functional theory, we study the structural, energetic and electronic properties of subsurface substitutional oxygen atoms on the X layers of MXenes of the form M2XT2, with M = Ti, V; X = C, N; and T = none, O or F. According to the calculations, subsurface O is thermodynamically stable in any concentration on all the analysed MXenes.Subsurface substitutional O atoms in the Ti2C MXene are thermodynamically driven towards the surface, leaving behind vacancies and creating local O surface terminations. Given that this process involves a very low energy barrier, we predict that, under conditions suitable for eliminating the surface termination of MXenes, many vacancies on the layers of X atoms should occur.The O-terminated carbide MXenes, Ti2CO2 and V2CO2, are stable with their hexagonal symmetry up to a threshold amount of subsurface O, around 75 %, which is above the maximum experimentally observed concentration, 65 %. The F surface termination stabilizes the hexagonal structure of MXenes, which no longer distort regardless of the presence and amount of subsurface oxygen. This suggests that MXene synthesis routes based on fluorine-containing compounds are the most indicated for synthesising nitride MXenes.The PBE functional predicts the semiconductor characteristics of the Ti2CO2 MXene to be lost in the presence of subsurface O, even a percentage as low as 6 %, the lowest considered in this work. The hybrid HSE06 functional predicts the oxycarbide material to remain a semiconductor, but with a significantly lowered band gap energy with increasing substitutional O content. Nevertheless, both functionals agree that the mixture of C and O atoms between the Ti layers of the Ti2CO2 MXene increases its conductivity. To the best of our knowledge, this MXene has never been confirmed experimentally to behave as a semiconductor probably because the real samples of this MXene contain subsurface oxygen.

Comparative analysis of energy efficiency for three heating and cooling supply schemes in a region with hot summers and cold winters in a chemical industrial park

Building energy consumption in China accounts for 45% of the total national energy consumption, with air conditioning energy consumption representing approximately two-thirds of that. Therefore, energy efficiency in buildings is of utmost importance. This study focuses on a chemical industrial park located along the Fujiang River and compares three heating and cooling supply schemes: the river water source heat pump system, which utilizes river water as the heat source and heat sink; the water cooling unit and boiler system, which uses water-cooled electric compression chillers for cooling and an oil-fired boiler system for heating; and the split air conditioning and gas water heater scheme, which relies on refrigerants such as fluorine-containing compounds for cooling and a gas water heater for heating. By calculating the energy consumption of the above three schemes and conducting a comparative analysis, it is found that the river water source heat pump system exhibits significantly higher energy efficiency throughout the year compared to the water cooling unit and boiler system and the split air conditioning and gas water heater scheme. This highlights the notable energy efficiency advantage of the river water source heat pump system.

Antiviral Activity of Low-Molecular-Weight Fluorinated Compounds Against Influenza A (H1N1) Virus

Influenza A virus takes a stable position in annual acute respiratory disease outbreaks during the autumn-winter period. Antiviral drugs for influenza infection help significantly ease the course of the disease and prevent complications, but there is still no drug to which none of the circulating strains would be resistant. Therefore, the search for new effective drugs against influenza A virus is constantly being conducted, in particular among fluorine-containing organic compounds, taking into account the special properties of fluorine. The goal of the study is to investigate the activity of a group of low-molecular-weight fluorinated compounds against the influenza A (H1N1) virus and to determine the potential mechanism of their action using in silico methods. Methods. Five fluorinated compounds designated as 10S-45, 10S-46, 10S-47, 10S-48 and 10S-49 were studied. In vitro experiments were performed using MDCK cell culture, A/FM/1/47 strain of influenza A (H1N1) virus, and oseltamivir phosphate as a reference drug. The cytotoxic effect on cell culture was determined using the MTT test. Antiviral effect was investigated by post-exposure incubation of compound solutions with cells, and visualization of results was performed using crystal violet dye. The possibility of the interaction of compounds with the cap-binding domain (CBD) of the PB2 subunit of the RNA-dependent RNA polymerase (RdRp) of the virus was evaluated using molecular dynamics simulation. Results. It was established that the studied compounds have a moderate cytotoxic effect on MDCK cell culture: the calculated CC50 values are in the range of 471─577 μg/mL for 10S-45, 10S-46, 10S-47 and 10S-48. Substance 10S-49 is almost 2 times less toxic compared to the rest, but it also has no effect on the influenza virus. Compounds 10S-45, 10S-46 and 10S-48 demonstrate antiviral activity in the range of 12─78 % inhibition of viral reproduction with an inverse dose-dependent effect. Substance 10S-47 showed a relatively stable inhibition of viral reproduction in the range of 63─69 % at all tested concentrations, which is similar to the results of the reference drug. According to the results of the selectivity index calculation, compound 10S-48 has the highest value, and 10S-47 has the lowest one, for the rest of the substances, this indicator is acceptable, but low, compared to the reference drug. For in silico studies, all possible spatial forms of the compounds presented as a mixture of diastereoisomers were generated: 4 stereoisomers each for 10S-45 and 10S-46, as well as 3 for 10S-47. According to the results of molecular docking of substances to the active center of CBD, 10S-45 has the lowest calculated affinity, and 10S-47 has the highest. Accordingly, compound 10S-45 showed no tendency to form ordered interactions with CBD. The 10S-47/CBD complex was not characterized by the presence of stable orientational bonds between receptor and ligand, similar to 10S-48/CBD. However, compound 10S-46 showed a generally stable interaction with CBD, albeit with a period of conformational instability. Conclusions. All studied compounds (except for 10S-49) demonstrate an antiviral effect in vitro against the influenza A (H1N1) virus. Based on the results of the in silico analysis of their interactions with CBD PB2, compound 10S-46 is highly likely to be an inhibitor of the cap-binding activity of RdRp.

СВОЙСТВА НИКЕЛЕВЫХ ПОКРЫТИЙ, ПОЛУЧЕННЫХ В ПРИСУТСТВИИ ТРИФЛАМИДОВ

The influence of fluorine-containing compounds (triflamides) in sulfuric acid electrolyte and electroly-sis modes on the properties of nickel coatings has been studied

Determination of seven perfluoroalkyl and polyfluoroalkyl substances in serum of pregnant women and evaluation of neonatal neurobehavior based on high performance liquid chromatography-tandem mass spectrometry

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been extensively used as synthetic fluorine-containing compounds in various consumer products, including surfactants, cookware, lubricants, clothing, and food packaging, since the 1950s. Evidence has shown that PFASs cross the placental barrier and interfere with fetal thyroid hormone homeostasis, which is crucial for fetal growth and neurobehavioral development in children aged 2-9 years. However, no epidemiological data on the association between prenatal PFAS exposure and neonatal neurobehavioral development are available. In this study, we explored the association between prenatal PFAS exposure and neonatal neurobehavioral development based on the Ezhou cohort study. Blood samples (10 mL) were collected during the third trimester of pregnancy (28-36 weeks) at the Ezhou maternal and child health hospital. The blood specimens were centrifuged at 4000 r/min for 15 min immediately after collection, separated, stored at -80 ℃. The samples were analyzed for seven PFASs, namely, perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroheptanesulfonic acid (PFHpS), and perfluorooctane sulfonamide (PFOSA). The PFASs were separated using a C18 column (100 mm×2.1 mm, 1.7 μm) at an oven temperature of 40 ℃, injection volume of 10 μL, and flow rate of 0.4 mL/min via gradient elution with methanol and ammonium acetate aqueous solution. The instrument was operated in negative electrospray ionization mode with multiple reaction monitoring. The correlation coefficients (r2), limits of detection (LODs) and quantification (LOQs), and spiked recoveries of the seven PFASs were 0.993-0.999, 0.006-0.020 ng/mL, 0.020-0.066 ng/mL, and 84.6%-116.8%, respectively. Neonatal behavioral neurological assessment (NBNA) was used to evaluate newborn cognitive development 72 h after birth; this tool consisted of five clusters, including behavior (six items), passive muscle tone (four items), active muscle tone (four items), primitive reflexes (three items), and general assessment (three items). Each item was rated on a three-point scale (0, 1, or 2), with the 20 items having a maximum score of 40. A total of 379 mother-newborn pairs were included in the analysis. The PFASs with the highest exposure levels was PFOA, with median levels of 19.4 ng/mL. Linear regression models were used to test the effects of ln-converted PFAS levels in newborns. After adjusting for confounding factors, the linear regression model showed that PFOS exposure during pregnancy was associated with decreased active muscle tone(β(95% CI): 0.36(-0.64, 0.08)) and general assessment(β(95% CI): 0.34(-0.61, 0.07)) in all newborns. Furthermore, PFNA exposure was associated with decreased passive muscle tone(β(95% CI): 0.38(-0.74, 0.01)) and total NBNA(β(95% CI): 0.37(-0.68, 0.06)). PFDA exposure was associated with decreased behavior(β(95% CI): 0.28(-0.54, 0.01)), while PFHxS exposure was associated with elevated total NBNA(β(95% CI): 0.27(0.05-0.48)). Gender stratification analysis showed that PFOS exposure during pregnancy was associated with decreased active muscle tone(β(95% CI): 0.54(-0.73, 0.35)) and general assessment(β(95% CI): 0.50(-0.88, 0.13)), PFNA exposure during pregnancy was associated with decreased passive muscle tone(β(95% CI): 0.67(-1.2, 0.14)) and total NBNA(β(95% CI): 0.45(-0.91, 0.01)), PFDA exposure during pregnancy was associated with decreased behavior(β(95% CI): 0.44(-0.71, 0.17)), PFHxS exposure was associated with elevated total NBNA(β(95% CI): 0.41(0.02-0.80)) in male newborns, and PFOA exposure was associated with decreased general assessment(β(95% CI): -0.27(-0.51, 0.02)), and PFDA exposure was associated with elevated behavior(β(95% CI): 0.46(0.40-0.52)) in female newborns. The proposed method separates and detects various PFASs without the need for cumbersome pretreatment processes, and has the advantages of low LODs, satisfactory recoveries, and accurate precision. Thus, it allows for the simultaneous analysis of trace PFASs in microserum samples from pregnant women. Our results also showed that prenatal PFAS exposure can lead to neurobehavioral disorders in offspring, with male newborns showing greater sensitivity than female newborns.

Design, synthesis, and biological evaluation of multiple F-18 S1PR1 radiotracers in rodent and nonhuman primate.

Here we report our design and synthesis of 28 new fluorine-containing compounds as potential F-18 radiotracers for CNS imaging of sphingosine-1-phosphate receptor 1 (S1PR1), and determination of their in vitro binding potency and selectivity toward S1PR1 over other S1PR subtypes. Nine potent and selective compounds, 7c&d, 9a&c, 12b, 15b, and 18a-c with IC50 values ranging from 0.6-12.3 nM for S1PR1 and weak binding toward S1PR2, 3, 4, and 5, were further 18F-radiolabeled to produce [18F]7c&d, [18F]9a&c, [18F]12b, [18F]15b, and [18F]18a-c. Multi-step F-18 radiochemistry procedures were investigated for radiosynthesis of [18F]7c&d and [18F]9a&c, and the presumed intermediates were synthesized and authenticated by analytic HPLC. We then performed nonhuman primate (NHP) PET brain imaging studies for eight radiotracers: [18F]7c&d, [18F]9a, [18F]12b, [18F]15b, and [18F]18a-c. Three radiotracers, [18F]7c, [18F]7d, and [18F]15b, had high NHP brain uptake with standardized uptake values (SUVs) at 2 h post-injection of 2.42, 2.84, and 2.00, respectively, and good brain retention. Our ex vivo biodistribution study in rats confirmed [18F]7d had a high brain uptake with no in vivo defluorination. Radiometabolic analysis of [18F]7c and [18F]7d in rat plasma and brain samples found that [18F]7c has a more favorable metabolic profile than [18F]7d. However, the trend of increased brain uptake precludes [18F]7c as a suitable PET radiotracer for imaging S1PR1 in the brain. Further structural optmization is warranted to identify a highly S1PR1-specific radiotracer with rapid brain uptake kinetics.

A polymeric 1H/19F dual-modal MRI contrast agent with a snowman-like Janus nanostructure.

Magnetic resonance imaging (MRI) has emerged as a pivotal tool in contemporary medical diagnostics, offering non-invasive and high-resolution visualization of internal structures. Contrast agents are essential for enhancing MRI resolution, accurate lesion detection, and early pathology identification. While gadolinium-based contrast agents are widely used in clinics, safety concerns have prompted exploration of metal-free alternatives, including fluorine and nitroxide radical-based MRI contrast agents. Fluorine-containing compounds exhibit excellent MRI capabilities, with 19F MRI providing enhanced resolution and quantitative assessment. Nitroxide radicals, such as PROXYL and TEMPO, offer paramagnetic properties for MRI contrast. Despite their versatility, nitroxide radicals suffer from lower relaxivity values (r1) compared to gadolinium. Dual-modal imaging, combining 1H and 19F MRI, has gained prominence for its comprehensive insights into biological processes and disease states. However, existing dual-modal agents predominantly utilize gadolinium-organic ligands without incorporating nitroxide radicals. Here, we introduce a novel dual-modal MRI contrast agent (J-CA) featuring a Janus asymmetric nanostructure synthesized via seeded emulsion polymerization and post-modification. J-CA demonstrates excellent in vitro and in vivo performance in both 19F and 1H MRI, with a T2 relaxation time of 5 ms and an r1 value of 0.31 mM-1 s-1, ensuring dual-modal imaging capability. Moreover, J-CA exhibits superior biocompatibility and organ targeting, making it a promising candidate for precise lesion imaging and disease diagnosis. This work introduces a new avenue for metal-free dual-modal MRI, addressing safety concerns associated with traditional contrast agents.

Trifluoromethylnitrone: a versatile building block for synthesizing trifluoromethyl-containing heterocyclic compounds.

This review explores the significance of trifluoromethylnitrones in synthesizing fluorine-containing compounds, with a particular focus on trifluoromethylated heterocycles. It explores the versatility of trifluoromethylnitrones, especially in [3 + 2] cycloaddition reactions, highlighting their unique reactivity with various dienophile substrates. Trifluoromethylnitrones are valuable precursors for the rapid synthesis of medicinally important trifluoromethylated heterocycles, including isoxazolidines, dihydroisoxazoles, oxathiazolidines, β-lactams, and aziridines. These heterocycles, in turn, serve as synthons for synthesizing trifluoromethylated lactams and aminoalcohols. Additionally, nitrone chemistry extends to synthesizing trifluoromethylated nucleosides and trifluorinated organoborane heterocycles, demonstrating their versatility. While sharing similarities with trifluorodiazoethane reactivity, trifluoromethylnitrones offer distinct advantages by enabling the synthesis of heterocycles typically inaccessible with trifluorodiazoethane.

Reducing Occupational Risks and Greening a Traditional Sample Treatment of Industrial Fluorine Containing-materials by Application of Design of Experiments

Despite the new technological advances, some traditional methodologies concerning wet chemistry must be used as reference methods when dealing with complex matrices or when no certified reference materials are available. In this context, Willard-Winter distillation is nowadays still employed as a reference technique for fluorine extraction in day-to-day analysis. However, this procedure requires strong acid mixtures, increasing waste treatment procedures/costs and the potential risks associated with their use. The present work reports the application of design of experiments (DoE) to improve the analytical methodology of reference for fluorine extraction through Willard-Winter distillation by substituting perchloric acid. Variables affecting the sample treatment of fluorine-containing compounds, anhydrite, fluorspar, cryolite and aluminium fluoride were studied to ensure complete dissolution and total extraction of fluorine. Volume of sulfuric acid, sample amount, volume of distilled solution including volume of melt and amount of NaOH for fluorspar and the extended fluoroaluminate compounds were the variables studied. Predicted experimental conditions were performed and validated in the target compound, obtaining fluorine concentrations comparable to those obtained by the reference methodology. By this modified approach, not only harmful effect of manipulation of perchloric acid is reduced but also costs of the analytical procedure do so. Besides, a greener performance is achieved by avoiding chlorinated species, reducing waste dangerousness and its treatment.

Morbidity rates of the children population under conditions of aerogenic chemical exposure: risk factors and associations

Introduction. In the the industrialized regions of the Russian Federation one of the hygienic problems is the formation of additional morbidity among the population associated with intense air pollution.
 The purpose of the work is to study the health disorders in children under conditions of aerogenic chemical exposure in terms of primary morbidity.
 Materials and methods. Analysis of the primary morbidity of the children population (data from state statistical reporting and actual seeking medical care in 2017–2021); the content of the main chemical pollutants in the atmospheric air in residential buildings (data from social and hygienic monitoring and the regular observation network of Roshydromet for 2016–2020 according to the content of twenty two impurities); chronic non-carcinogenic risk; connection of diseases with aerogenic chemical exposure according to epidemiological indicators; economic assessment of predicted losses.
 Results. Comparing to the reference area, the level of primary morbidity in children with diseases of the respiratory system, digestion, kidneys, nervous system, osteoarticular apparatus, associated with aerogenic exposure to chemical pollutants, was established to be an increased by up to 3.4 times. In the atmospheric air of residential buildings, the content of a number of chemicals (metals, aromatic and fluorine-containing inorganic compounds) was found to be increased by 6.9 times and 4.0 times relative to the average daily and maximum one-time maximum permissible concentrations, respectively, and within the hygienic standards. The formed exposure causes an unacceptable risk of developing non-carcinogenic effects (HI up to 18.7 times) in relation to target organs. Additional morbidity in the children population (about 1.5 thousand cases per year) has been identified in the event of which the projected economic losses will amount to about 10 million rubles over year.
 Limitations. The study includes the children population under the age of 14 years.
 Conclusion. The primary morbidity of children in regions with developed industrial infrastructure is characterized by special random events associated with aerogenic exposure to risk factors. Projected additional losses require priority regulatory action.

Surface Fluorinated Metastable Aluminum Microspheres: Improved Ignition and Anti-Aging Properties of Aluminum Powder

ABSTRACT Incorporating fluorine-containing organic compounds onto the surface of aluminum powder in order to reduce the mass transfer distance and increase the heat transfer efficiency during the combustion of aluminum powder and fluoride is a difficult problem to solve due to the fact that aluminum powder contains almost no chemical functional groups. Herein, monodisperse Al@PVDF microspheres were prepared by a simple dry-spray method by directly combining Al powder and PVDF. The contents of PVDF and Al in Al@PVDF microspheres can be adjusted arbitrarily. PVDF can be tightly and uniformly bound on the surface of aluminum particles by characterization of Al@PVDF microspheres. Al@PVDF microspheres can improve the hydrophobic properties of aluminum powder and effectively inhibit the corrosion of water and strong alkaline solutions on aluminum. Al@PVDF microspheres exhibit greater hydrophobicity than aluminum powder and are capable of efficiently inhibiting the corrosion of aluminum by water and strong alkaline solutions. Additionally, the ignition and reaction performance of Al@PVDF microspheres under high temperature conditions are also studied in detail. Al@PVDF microspheres exhibit lower ignition temperature and higher reactivity than pure aluminum powder. Al@PVDF microspheres can also effectively suppress the combustion agglomeration of aluminum powders.

Effect of substituents on the properties of fluorine-containing polyphenyl liquid crystal compounds

In order to explore the influence of molecular structure on the properties of liquid crystal (LC) materials, the dielectric anisotropy, rotational viscosity coefficient and birefringence of different fluorine-containing polyphenyl LC compounds are measured experimentally. The effects of lateral substituents and terminal substituents are analyzed. The experimental results show that the substitution of fluorine substituents in lateral substituents or terminal substituents will lead to the decrease of rotational viscosity coefficient, whether it is fluorine-containing triphenyl LC compounds or fluorine-containing tetraphenyl LC compounds. The dielectric anisotropies of LC compounds (fluorine-containing tetraphenyl LC compounds ND-3 and ND-8, ND-4 and ND-9, and ND-1 and ND-10) in which the terminal isothiocyano substituents are substituted by fluorine substituents all show a downward trend, with the decreasing degrees of 41.3%, 20.7% and 19.2% respectively. In addition to the influence of the replacement of fluorine and isothiocyanato on the terminal substituents, the dielectric anisotropy is affected by different lateral substituents from large to small: fluorine, methyl, and ethyl. The lateral fluorine substitution impact of ND-3, with an increase of 9.4%, is the best among fluorine-containing tetraphenyl LC compounds when compared to the lateral ethyl substitution of ND-2. Besides, compared with -F, -NCS can effectively extend the π-electron conjugation length of the molecule and improve the birefringence of the LC. This research is of great help to improve the comprehensive properties of LC materials and provides data accumulation for the development and application of LC compounds.

Synthesis of α-Trifluoromethyl Alkynes through Fluoroalkynylation of gem-Difluoroalkenes.

A trifluoromethylalkynylation reaction of gem-difluoroalkenes with alkynyl sulfoxide by photoredox radical addition with good functional group tolerance in moderate to high yields, is developed for the synthesis of α-trifluoromethyl alkyne. This reaction features simple operation and inexpensive raw materials and provides an expeditious route to synthesize biologically relevant fluorine-containing alkynyl compounds with diverse structural skeletons.

Quantitative NMR external standard fit-for-purpose method for fluorine-containing compounds: Expanding the application of aSSICO signal method to 19F nuclei

The design of fluorinated pharmaceuticals has become an important approach in drug discovery given fluorine's ability to modulate properties such as lipophilicity, pKa, metabolic stability, and bioavailability offering desired therapeutic advancements over a drug's hydrogen counterpart. Characterizing these compounds builds our understanding of how fluorine's structural and positional attributes influence the properties of these pharmaceuticals. NMR spectroscopy is a powerful structural characterization tool well-suited for this purpose. In this paper we present a quantitative pharmaceutical application using fluorine NMR and aSICCO (artificial Signal Insertion for Calculation of Concentration Observed) for analyzing pure or crude samples containing fluorinated pharmaceuticals and fluorinated residual solvents. We demonstrate that the method can be applied to samples measured with routine NMR instrumentation, achieving reproducible results to within ± 5 percent.

Fluorine-tailed glass fibers for adsorption of volatile perfluorinated compounds via F-F interaction

Perfluorinated compounds (PFCs) and their short-chain derivatives are contaminants found globally. Adsorption research on volatile perfluorinated compounds (VPFCs), which are the main PFCs substances that undergo transfer and migration, is particularly important. In this study, new fluorine-containing tail materials (FCTMs) were prepared by combining fluorine-containing tail organic compounds with modified glass fibers. The adsorption effects of these FCTMs were generally stronger than that of pure activated glass fibers without fluorine- tailed, with an adsorption efficiency of up to 86% based on F–F interactions. The results showed that the FCTMs had improved desorption efficiency and reusability, and higher adsorption efficiency compared with that of polyurethane foam. FTGF was applied to the active sampler, and the indoor adsorption of perfluorovaleric acid was up to 2.45 ng/m3. The adsorption kinetics and isotherm simulation results showed that the adsorption process of typical perfluorinated compounds conformed to the second-order kinetics and Langmuir model. Furthermore, Nuclear Magnetic Resonance (NMR) results showed that the chemical shift in the fluorine spectrum was significantly changed by F–F interactions. This research provides basic theoretical data for the study of VPFCs, especially short-chain VPFCs, facilitating improved scientific support for the gas phase analysis of VPFCs in the environment.

Assessment of the Commercially Available Chemical Space for Using in the 19F NMR FAXS Method: a Enamine Ltd. Case

Aim. To analyze commercially available fluorine containing compounds for the possibility of their use in the 19F NMR FAXS method.Materials and methods. The selection of fluorine-containing fragments for the study was performed using 3.9 million instock screening compounds and 248,000 in-stock building-blocks from Enamine Ltd library. The selection and classification of the compounds was carried out using the DataWarrior and KNIME software. The Fluorinated Fragments library of Enamine Ltd. containing 6377 compounds, was also analyzed. To analyze the abovementioned sets of substances, the multistep workflows specially designed were used.Results and discussion. As a result of applying the workflow developed to the compound sets (both screening compounds and building blocks), 13 800 compounds were selected and further classified according to the presence of one out of 12 fluorine-containing groups. The Fluorinated Fragments library was also subjected to a similar workflow. For the latter, 8 out of 12 fluorine-containing groups were identified. Additionally, experimental 19F NMR chemical shift values for Fluorinated Fragments library compounds spectra were analyzed. It has been found that some structural classes have areas of chemical shifts intersection. On the other hand, the ranges from –40 to –60 ppm and beyond –160 ppm are free from any group of compounds from the library analyzed.Conclusions. The analysis has shown that commercially available fluorine-containing fragments do not satisfy the needs of the 19F NMR FAXS method, and further expansion of the chemical space of fluorine-containing compounds by increasing their diversity is required.