CF3 Group Research Articles

Sectional measurements of shoulder muscle volume and computed tomography density in anterior shoulder instability

In patients with anterior shoulder instability (ASI), a chronic imbalance might exist between the anterior and posterior shoulder muscles (i.e., subscapular [Ssc] vs. infraspinatus and teres minor [Isp + TM]). The balance could be evaluated as the ratio of volume (VR Ssc/Isp+TM) and computed tomography density (CT-DR Ssc/Isp+TM) using a 3D sectional approach. A total of 28 CT images (19 patients) of non-pathological shoulders (clavicular fracture [CF]) and 17 CT images (17 patients) of ASI were used. Segmentation of Ssc and Isp + TM muscles was performed; the reconstructed models were separated by the Y-view plane and the planes situated 2.5 cm and 5 cm medial to the Y-view plane to generate muscle models. VR Ssc/Isp+TM and CT-DR Ssc/Isp+TM were measured in each section of both the groups, as well as in whole muscle measurements in the CF group. VR Ssc/Isp+TM and CT-DR Ssc/Isp+TM obtained through a 3D sectional approach in the CF group were comparable to the whole muscle measurements, with a value of 1.06 for both. In the ASI group, the VR Ssc/Isp+TM was higher, whereas the CT-DR Ssc/Isp+TM was lower than those in the CF group. The VR Ssc/Isp+TM and CT-DR Ssc/Isp+TM appeared to be balanced in the CF group. However an imbalance was observed in the ASI group. Our 3D sectional measurement approach has the potential to assess the balance between the anterior and posterior shoulder muscles in ASI.

Mn(I)‐Catalyzed C−H Allylation of Indoles with 2‐Vinylaziridines

AbstractMn(CO)5Br‐catalyzed reaction of 1‐(2‐pyrimidyl)indoles with 1‐sulfonyl‐2‐vinylaziridines in THF in the presence of 0.25 equiv. of NaOAc affords 2‐allylated indoles in 31 % to 100 % yields. The protocol suits for 3‐, 4‐, 5‐, 6‐, and 7‐substituted indoles and N‐(2‐pyrimidyl)pyrroles as well as various 1‐(arylsulfonyl)‐2‐vinylaziridines such as 1‐(phenylsulfonyl)‐2‐vinylaziridine, 1‐(naphthalen‐2‐ylsulfon‐yl)‐2‐vinylaziridine, and 1‐(substituted phenylsulfonyl)‐2‐vinylazirid‐ines. Functional groups including alkyl, alkoxy, halogen, CHO, COOMe, CF3, CN, and NO2 groups are tolerated.

In Situ Gel Polymer Electrolyte with Rapid Li+ Transport Channels and Anchored Anion Sites for High‐Current‐Density Lithium‐Ion Batteries

AbstractIn situ formed gel polymer electrolytes (GPEs) have advantages in safety and adaptability to current high‐voltage lithium‐ion batteries (LIBs). However, it is challenging for GPEs to achieve stable cycling at high current densities. A flexible framework is proposed for stable in situ GPE, by introducing ─CF3 groups to the polymer network to establish rapid Li+ transport channels, and incorporating secondary amine N─H groups to anchor anion. The obtained GPE exhibits a high ionic conductivity of 2.6 mS cm−1 and a high Li+ transference number of 0.67. The assembled Li||NCM811 cell demonstrates excellent rate performance, with a discharging capacity of 112.3 mAh g⁻¹ at 10C, and capacity retention of 87.6% after 260 cycles at 1C. Furthermore, the assembled graphite||NCM811 cell demonstrates excellent long‐term cycling stability with impressive capacity retention of 73.2% after 300 cycles 3C (1.8 mA cm−2). This work presents a promising approach to enhancing the cycling stability of GPEs for high‐voltage LIBs at high current density.

Consecutive Trifluoromethylation of C88(7) Fullerene: A Theoretical Study

AbstractThe trifluoromethylation of C88(7) fullerene has been systematically studied using an energy‐controlled consecutive CF3 addition approach. The thermodynamically favored C88(7)(CF3)2n isomers with 2n = 2–20 were predicted at the DFT B3LYP‐D3BJ/6–311G* level of theory for the first time, in harmony with the two experimentally characterized isomers C88(7)(CF3)12/16. It was found that these stable isomers are formed mainly by 1,4‐additions of CF3 groups, and meanwhile, there are a few stable isomers with isolated CF3 groups for 2n ≤ 12, with ortho addition for 2n > 12, and with triple‐hexagon‐junction addition for the highest degree of trifluoromethylation (2n ≥ 18). The addition patterns of CF3 groups were discussed in terms of the local structural motif of the pristine cage and the formation of stabilizing substructures of local aromaticity. The possible trifluoromethylation pathways of C88(7) were proposed on the basis of the relative Gibbs free energies. The results show that almost all the intermediate isomers for the thermodynamically most stable isomers of C88(7)(CF3)2n possess low relative Gibbs free energies (below 14 kJ·mol−1). Moreover, the hardness, chemical potential, electrophilicity index, electron affinity, HOMO and LUMO energies, and HOMO–LUMO gaps of the thermodynamically most stable C88(7)(CF3)2n isomers were also calculated.

Metabolomics reveals changes in levels of fecal branched chain amino acids and organic acids in very preterm infants fed human milk fortified with bovine colostrum

Background & aimsHuman milk is the optimal diet for very preterm infants (VPIs), but it requires nutrient fortification to support growth. Bovine colostrum (BC), rich in intact proteins and bioactive components, could serve as a novel fortifier with potential benefits to VPIs gut health. To evaluate a possible effect of feeding BC on intestinal metabolism, the gut microbiota, and their interaction, we studied the fecal metabolome of VPIs in the first month of life, as compared with a conventional fortifier (CF, based on infant formula ingredients). MethodsFecal samples were collected from VPIs recruited to the FortiColos trial (NCT03537365, BC, n = 107; CF, n = 112) before (FT0) and one (FT1) or two (FT2) weeks after start of fortification and analyzed using 1H NMR spectroscopy. Abundances of metabolites were compared between BC versus CF groups. Further, temporal changes in metabolite levels after start of fortification, as well as correlations with specific gut bacterial genera were explored. ResultsInfants in the BC group had higher levels of fecal acetoacetate, choline, methanol, uracil, creatine, creatinine, lysine and a lower leucine at both FT1 and FT2, relative to the CF group. Asparagine, tryptophan and phenylalanine levels were higher, and butyrate was lower in the BC group at FT1. At FT2, higher fecal succinate and lower isoleucine were found in the BC group. In addition, eight metabolites (asparagine, phenylalanine, tryptophan, lysine, creatinine, acetoacetate, methanol and uracil) had fortification-specific changes over time. Correlations were found between succinate and unclassified Enterobacteriaceae, butyrate and Clostridium, uracil and Staphylococcus, as well as unclassified Enterobacteriaceae members. ConclusionOur study shows distinct fecal metabolome profiles in VPIs in the first weeks after fortification with BC versus CF. The fortification- and time-specific gut metabolite changes suggest that fortifiers influence luminal nutrient metabolism and microbiota activity in VPIs. Fortifier type for human milk affected gut health of VIPs via altered gut metabolite levels, interacting with microbiota in VPIs.

Epigenetic insights into creep-feeding: methylation profiling of Longissimus thoracis muscle at weaning in crossbred cattle

IntroductionThis study investigated the impact of creep-feeding supplementation on the genome methylation of the Longissimus thoracis (LT) muscle in crossbred beef cattle (Bos taurus × Bos indicus).MethodsThe experiment involved 48 uncastrated F1 Angus-Nellore males (half-siblings), which were divided into two groups: NCF – no creep-feeding (n = 24) and CF – creep-feeding (n = 24). After weaning at 210 days, all animals were feedlot finished for 180 days under identical conditions. LT muscle biopsies were collected at weaning for genomic DNA methylation analysis by reduced representation bisulfite sequencing (RRBS).Results and discussionThe groups differed significantly (CF > NCF: p < 0.05) to weaning weight (243.57±5.70 vs. 228.92±5.07kg), backfat thickness (12.96±0.86 vs. 10.61±0.42mm), LT muscle marbling score (366.11±12.39 vs. 321.50±13.65), and LT intramuscular fat content (5.80±0.23 vs. 4.95±0.20%). The weights at the beginning of the experiment and at slaughter (390 days) did not differ significantly. Mean methylation levels were higher in CF with 0.18% more CpG, 0.04% CHG, and 0.03% CHH. We identified 974 regions with differential methylation (DMRs: > 25% and q < 0.05), which overlapped with 241 differentially methylated genes (DMGs). Among these genes, 108 were hypermethylated and 133 were hypomethylated in CF group. Notably, 39 of these DMGs were previously identified as differentially expressed genes (DEGs: log2 fold change [0.5]) in the same animal groups. Over-representation analysis highlighted epigenetic regulations related to muscle growth, PPAR signaling, adipogenesis, insulin response, and lipid metabolism. Key DMGs/DEGs included: ACAA1, SORBS1, SMAD3, TRIM63, PRKCA, DNMT3A, RUNX1, NRG3, and SLC2A8. These epigenetic changes improved the performance of supplemented animals up to weaning and enhanced meat quality traits, particularly higher intramuscular fat. The results provided insights into the intricate interplay between nutrition, epigenetics, gene expression and phenotypes in beef cattle production.

In-plane orientational motions of the functional groups of molecules at the air/water interface by time-resolved vibrational sum frequency generation.

The movements of molecules at interfaces and surfaces are restricted by their asymmetric environments, leading to anisotropic orientational motions. In this work, in-plane orientational motions of the -C=O and -CF3 groups of coumarin 153 (C153) at the air/water interface were measured using time-resolved (TR) vibrational sum frequency generation (SFG). The in-plane orientational time constants of the -C=O and -CF3 groups of C153 are found to be 41.5 ± 8.2 and 36.0 ± 4.5ps. These values are over five-times faster than that of 198 ± 15ps for the permanent dipole of the whole C153molecule at the interface, which may indicate that the two groups experience different interfacial friction in the plane. These differences could also be the result of the permanent dipole of C153 being almost five times those of the -C=O and -CF3 groups. The difference in orientational motions reveals the microscopic heterogeneous environment that molecules experience at the interface. While the interfacial dynamics of the two functional groups are similar, our TR-SFG experiments allowed the quantification of the in-plane dynamics of individual functional groups for the first time. Our experimental findings about the interfacial molecular motion have implications for molecular rotations, energy transfer, and charge transfer at material interfaces, photocatalysis interfaces, and biological cell/membrane aqueous interfaces.

Oral biofilm composition and phenotype in caries-active and caries-free children.

During development of dental caries, oral biofilms undergo changes in microbial composition and phenotypical traits. The aim of this study was to compare the acid tolerance (AT) of plaque from two groups of children: one with severe caries (CA) and one with no caries experience (CF) and to correlate this to the microbial composition and metabolic profile of the biofilms. Dental plaque samples from 20 children (2-5 years) in each group were studied. The AT was analyzed by viability assessment after exposure to an acid challenge (pH 3.5), using LIVE/DEAD® BacLight™ stain and confocal microscopy. Levels of acid tolerance (AT) were evaluated using a scoring system ranging from 1 (no/low AT), to 5 (high/all AT). Metabolic profiles were investigated following a 20 mM glucose pulse for one hour through Nuclear Magnetic Resonance (NMR). Microbial composition was characterized by 16S rRNA Illumina sequencing. The mean AT score of the CA group (4.1) was significantly higher than that of the CF group (2.6, p < 0.05). When comparing the end-products of glucose metabolism detected after a glucose-pulse, the CA samples showed a significantly higher lactate to acetate, lactate to formate, lactate to succinate and lactate to ethanol ratio than the CF samples (p < 0.05). The bacterial characterization of the samples revealed 25 species significantly more abundant in the CA samples, including species of Streptococcus, Prevotella, Leptotrichia and Veillonella (p < 0.05). Our results show that AT in pooled plaque from the oral cavity of children with severe caries is increased compared to that in healthy subjects and that this can be related to differences in the metabolic activity and microbial composition of the biofilms. Thus, the overall phenotype of dental plaque appears to be a promising indicator of the caries status of individuals. However, longitudinal studies investigating how the AT changes over time in relation to caries development are needed before plaque AT could be considered as a prediction method for the development of dental caries.

Copper-Catalyzed Defluorinative [3 + 2] Cyclization of Amidines and Trifluoromethyl Carbenoids for the Synthesis of 5-Fluoroimidazoles.

A Cu-catalyzed [3 + 2] cyclization of amidines with trifluoromethyldiazo compounds is described. The reaction affords 5-fluoroimidazoles in good yields by cleaving dual C-F bonds in a CF3 group. Using 2-aminoazo heterocycles as the substrates, various annelated imidazoles containing a fluorine atom were also constructed by this method without changing the conditions. The resultant 5-fluoroimidazoles show high reactivity toward SNAr reactions with a series of nucleophiles.

Au(I)/Au(III)-Catalyzed Sulfonylation of Aryl Iodides for the Synthesis of Various Functionalized Aryl Sulfones.

A gold-catalyzed sulfonylation reaction of aryl iodides with different sodium sulfinates facilitated by the ligand-enabled Au(I)/Au(III) redox catalysis was developed. In the reaction of gold-catalyzed C-S coupling, a variety of functionalized sodium sulfinates, such as CF3, CHF2, CH3, and alkyl groups, can react smoothly with aryl iodides to directly construct diversely functionalized aryl sulfones. This gold-catalyzed sulfonylation offers a complementary method for synthesizing functionalized aryl sulfones with electron-donating groups.

Engineering Trifluoromethyl Groups in Porous Coordination Polymers to Enhance Stability and Regulate Pore Window for Hexane Isomers Separation.

Effective separation of hexane (C6) isomers is critical for a variety of industrial applications but conventional distillation methods are energy-intensive. Adsorptive separations based on porous coordination polymers (PCPs) offer a promising alternative due to their exceptional porosity and tunable properties. However, there is still an urgent need to develop PCPs with high stability and separation performance. This study investigates how substituting a methyl (-CH3) group with a trifluoromethyl (-CF3) group can regulate pores and hydrophobicity in PCPs. This precise adjustment aims to enhance stability and improve the kinetic separation performance of hydrophobic C6 isomers by considering the size and hydrophobicity of the trifluoromethyl group. Two isostructural PCPs with pcu topology, PCP-CH3 and PCP-CF3, were synthesized to vary pore diameters and hydrophobicity based on the presence of -CH3 or -CF3 groups. PCP-CF3 showed greater stability in water compared to PCP-CH3. While PCP-CH3 had high adsorption capacities, it lacked selectivity, whereas PCP-CF3 demonstrated improved selectivity, particularly in excluding dibranched isomers. Dynamic column separation experiments revealed that PCP-CF3 could selectively adsorb linear and monobranched isomers over dibranched isomers at room temperature. These findings highlight the potential of fluorine-modified PCPs for efficient isomer separation and underscore the importance of stability improvement strategies.

Computational exploration of novel ketoprofen derivatives: Molecular dynamics simulations and MM-PBSA calculations for COX-2 inhibition as promising anti-inflammatory drugs

Computer-aided drug design is widely employed to identify novel compounds for therapeutic applications. Ketoprofen (KTP), a commonly used and marketed nonsteroidal anti-inflammatory drug (NSAID), is effective in treating pain, fever, inflammation, and some cancers. In this research, we explored the behavior of six analogues designed by structurally modifying the KTP molecule. Specifically, KTP-A and KTP-B contain a –CN group at the ortho position, KTP-C and KTP-D have a –CN group at the meta position, and KTP-E and KTP-F feature a –CF3 group at the meta position. To assess these analogues, we conducted molecular dynamics simulations (MD) to study their inhibitory effects on human cyclooxygenase 2 (COX-2), providing detailed insights into the structure and dynamics of the protein both with and without ligands. MD simulation, enhanced by technological advances, has proven to be a powerful tool for new drug discovery. We further quantified the binding affinity of these drug molecules toward COX-2 using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding free energy calculations. The dynamic properties were evaluated through analyses of root mean square deviations (RMSD), root mean square fluctuations (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA), covariance matrix, principal component analysis (PCA), and Gibbs free energy landscapes (FEL). Ultimately, this study confirms that the six KTP derivatives are promising candidates for the treatment of inflammation, with KTP-B standing out as particularly effective.

Anion-driven C[sbnd]F bond cleavage of trifluoromethyl N-aryl hydrazones toward the assembly of N-heterocycles

Herein we report an efficient and convenient method for synthesizing 1H-benzo[d]imidazoles via a base-promoted reaction of readily available α-CF3 ketone-derived hydrazones with o-phenylenediamines. The key innovation is the anion-driven triple-cleavage of the CF bond in the CF3 group, which acts as a C1 synthon at the 2-position of the 1H-benzo[d]imidazole. This novel approach simplifies the synthesis and can be extended to the preparation of benzo[d]oxazoles and benzo[d]thiazoles. Our method offers a versatile and robust platform for the synthesis of important heterocyclic compounds, with potential applications in medicinal chemistry and drug discovery.

Mechanically Robust Polyimide Binder Realizes Stable and High Electrochemical Performance for Micro-Silicon Anodes in Lithium-Ion Batteries.

Silicon is regarded as a highly promising anode material for lithium-ion batteries, attributed to its substantial theoretical specific capacity. The practical implementation of Si-anodes is hindered by side reactions and significant volumetric changes, ~300% to 400%, occurring during the lithiation/delithiation processes. Pertinent binders can effectively mitigate the stress resulting from the volumetric exchange in Si-anodes. Herein, we developed a mechanically stable polyimide binder PI-CF3 and introduced trifluoromethyl and hydroxyl groups for commercial microparticular Si-anodes. With the highest Young's modulus of ~921.1 MPa, the binder presented the maximum resilience during the charging and discharging of Micro-Si, integrating the morphology, and reducing the degree to which the electrode disrupted ion and electric pathways. Moreover, -OH and -CF3 groups of the binder could potentially interact with the oxide layer at the surface of silicon through H-bonds resulting in a cross-linking network to improve interface stability. The as-prepared PI-CF3 binder with excellent intrinsic mechanical and electro-rich groups stabilizes the electrode structure and facilitates fast Li+ transportation. Consequently, at 0.6 Ag-1, the micro-Si anode produced an initial specific capacity of 1838 mAh g-1 at Si 0.66 mg cm-2. Besides, at Si 0.78 mg cm-2 specific capacity retained around 1219 mAh g-1 over 330 cycles.

Triflate Salts as Alternative Non-Chlorinated Oxidants for the Oxidative Chemical Vapor Deposition and Electronic Engineering of Conjugated Polymers.

Oxidative chemical vapor deposition (oCVD) stands as an attractive approach for the synthesis, engineering, and integration of conjugated polymers for advanced electronic and optoelectronic applications. In oCVD, the oxidant significantly influences the conformational and optoelectronic properties of the resulting conjugated polymer thin films. In this work, triflate salts of iron(III) and copper(II) (Fe(OTf)3 and Cu(OTf)2, respectively) are investigated for the first time as suitable alternative oxidants to the widely used iron(III) chloride (FeCl3) for the oCVD of conjugated polymers. Structural and compositional characterizations of the resulting thin films evidenced the successful polymerization of cobalt(II) 5,15-diphenyl porphyrin using either Fe(OTf)3 or Cu(OTf)2. Along with an intermolecular dehydrogenative C-C coupling reaction, the occurrence of side reactions, such as the inclusion of -CF3 groups and demetalation and subsequent insertion of copper(II) in the porphyrin macrocycle when using Cu(OTf)2, were evidenced. Interestingly, the inclusion of -CF3 groups into the polymer backbone when using triflate salts results in a deepening of the frontier energy levels, while the insertion of copper(II) contributes to a reduction in the band gap energy. This work demonstrates that the careful selection of the oxidant agent in oCVD enables fine-tuning the optoelectronic properties of conjugated polymers to suit specific application requirements.

Modulating Electrostatic Properties and Noncovalent Interactions via Structural Isomerism: The Microwave Spectra and Molecular Structures of (E)- and (Z)-1,2,3,3,3-Pentafluoropropene and Their Gas-Phase Heterodimers with the Argon Atom.

Microwave spectra of both the E and Z isomers of 1,2,3,3,3-pentafluoropropene along with all three of the singly substituted 13C isotopologues for each are obtained using broadband chirped-pulse Fourier transform microwave spectroscopy from 2.0-18.1 GHz. Associated quantum chemistry calculations show that the barrier to internal rotation of the CF3 group is significantly higher for the Z isomer, which is stabilized by an intramolecular hydrogen bond, although the barriers in both isomers are sufficiently high to prevent the observation of any effects due to internal rotation. The normal isotopologues of the argon heterodimers for both isomers are also observed in the broadband spectrum and a Balle-Flygare cavity Fourier transform microwave spectrometer is used to obtain the 5.0-20.6 GHz spectra of the corresponding 13C isotopologues. In each case, the argon atom locates so as to maximize its interactions with areas of significant electron density. However, mapped electrostatic potential surfaces indicate that the areas of greatest nucleophilicity are different for the two isomers, suggesting that they may interact differently in forming heterodimers with protic acids.

The influence of functional groups on the pyrolysis of per- and polyfluoroalkyl substances

Thermal treatment is a widely used remediation strategy for PFAS-contaminated materials such as soil, spent sorbents, and domestic waste. To better understand the effectiveness and environmental impact of thermal treatments for PFAS-contaminated materials, a fundamental understanding of PFAS thermal degradation mechanisms is required. This work aims to study the pyrolysis of six representative PFAS compounds, all of which have an eight-carbon length but with different functional groups. To assess the thermal stability and pyrolysis products of these six PFAS compounds, evolved gas analysis (EGA) was performed using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) coupled with an infrared spectrometer (IR) and a mass spectrometer (MS), as well as pyrolysis-GCMS (Pyr-GCMS). The EGA data demonstrates that compounds with lower estimated vapor pressures were generally found to be more thermally labile, and the presence of an ionic bond necessitates higher temperatures for pyrolysis. Pyrolysis at 900 °C yielded a variety of fluorinated organic compounds at significant signals. Tetrafluoroethene constituted the majority of the Pyr-GCMS signal for all the compounds. Moreover, a significant fraction of detected products was unable to be identified, underscoring a need for better tools to help with the identification of unknowns. Pyrolysis can occur through random chain scission, scission of the functional group, scission of the terminal CF3 group, and HF elimination. Some compounds may undergo more complete beta-scission to produce smaller pyrolysis products compared to others. The presence of acidic protons within the functional group can help facilitate HF elimination, whereas the salt form of a PFAS compound is less likely to undergo HF elimination. Termination of radical intermediates can either be recombination with a CF3 radical or hydrogen abstraction (H-abstraction). Observed hydrogen-substituted products indicate that functional groups with higher hydrocarbon character may lead to more H-abstraction terminated products. Overall findings show that the functional group of a PFAS may decrease or increase its thermal stability and lead to different profiles of pyrolysis products.

Skeletal Editing through Single-Atom Insertion and Transmutation: An Insight into a New Era of Synthetic Organic Chemistry

AbstractConsidering the importance of heterocycles, significantly represented in medicinal chemistry and drug development, the single-atom insertion technique and transmutation strategy provide productive approaches towards complicated molecular structures through heterocycle diversification. It shows a potentially powerful approach for modifying complex substrates concisely and chemospecifically. Although skeletal editing applies to cyclic and acyclic compounds, this review focuses on the diversification of carbo- and heterocyclic compounds for synthesizing various medicinally important molecules via the single-atom insertion technique. The classification system is based on recent and critical historical methods of single-atom insertion as applied to the transmutation of aromatic rings.1 Introduction2 Skeletal Editing through Carbon-Atom Insertion2.1 Skeletal Editing of Indoles and Pyrroles Derivatives: Carbon-Atom Insertion into a C=C Bond2.2 Skeletal Editing of Pyrazole and Indazole Derivatives: Carbon-Atom Insertion into an N–N Bond2.3 Skeletal Editing of Pyrazole and Indazole Derivatives: Insertion of CF3 Group into Heteroarenes2.4 Skeletal Editing of Imidazole Derivatives: Carbon-Atom Insertion into C–N Bond2.5 Skeletal Editing through Atom-to-Atom Transmutation3 Skeletal Editing through N-Atom Insertion3.1 Nitrogen-Atom Insertion into Carbocycles3.2 Nitrogen-Atom Insertion into Heterocycles3.3 Carbon to Nitrogen Transmutation3.3 Molecular Editing through Isotopic Transmutation4 Conclusion

Defective MOF incorporating CF3 functionality via fragmented linker co-assembly for high C2H6/C2H4 selectivity and C2H6 uptake

The production of high-purity ethylene requires an adsorbent with high C2H6/C2H4 selectivity, outstanding C2H6 adsorption, and facile C2H6 regeneration. Towards this goal, a series of novel defective CF3-functionalized metal–organic framework (MOF) materials (UiO-66-nCF3, n = 25, 50, 60, and 75) were synthesized by co-assembling the framework with terephthalic acid as the linker and various percentages (n) of CF3-functionalized ligands. The C2H6 adsorption strength increased as the density of CF3 groups increased. In particular, UiO-66-50CF3 exhibited high C2H6/C2H4 selectivity (2.04), excellent C2H6 adsorption (2.5 mmol/g), and modest C2H6 isosteric heat of adsorption (Qst) (∼28.9 kJ/mol). Additionally, the material exhibited high C2H6/C2H4 breakthrough selectivity (1.64) and large high-purity (>99.9 %) C2H4 productivity (7.32 LSTP kg−1) under dynamic flow conditions (C2H6/C2H4 = 1:15 (v/v)). UiO-66-50CF3 could readily be regenerated at room temperature, and demonstrated good hydrothermal stability in boiling water for 1 h and high thermal stability up to 500 °C. The incorporation of a high density of CF3 groups within a MOF via fragmented linker co-assembly is a promising strategy for developing adsorbents for C2H6/C2H4 separation.

Mechanisms of Atomic Oxygen Erosion in Fluorinated Polyimides Investigated by Molecular Dynamics Simulations.

Traditional polyimides have highly conjugated structures, causing significant coloration under visible light. Fluorinated colorless polyimides, known for their light weight and excellent optical properties, are considered ideal for future aerospace optical lenses. However, their lifespan in low Earth orbit is severely limited by high-density atomic oxygen (AO) erosion, and the degradation behavior of fluorinated polyimides under AO exposure is not well understood. This study uses reactive molecular dynamics simulations to model two fluorinated polyimides, PMDA-TFMB and 6FDA-TFMB, with different fluorine contents, to explore their degradation mechanisms under varying AO concentrations. The results indicate that 6FDA-TFMB has slightly better resistance to erosion than PMDA-TFMB, mainly due to the enhanced chemical stability from its -CF3 groups. As AO concentration increases, widespread degradation of the polyimides occurs, with AO-induced cleavage and temperature-driven pyrolysis happening simultaneously, producing CO and OH as the main degradation products. This study uncovers the molecular-level degradation mechanisms of fluorinated polyimides, offering new insights for the design of AO erosion protection systems.