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Abstract The trade‐off between enhancing conductivity (σ) through doping while concurrently observing a reduction in the Seebeck coefficient (S) presents a key challenge in organic thermoelectrics. Here, a two‐step structural design strategy is developed, where the first step enhances the backbone planarity which enhances the conductivity by an improved ordering of conjugated polymers (CPs). The second step, which is fluorination of the backbone, improves the Seebeck coefficient by the controlled induction of energetic disorder, stemming from the fluorine's disruption of the homogeneous electrostatic potential across the CP backbone. This strategy is applied to two series of donor‐acceptor (D‐A) types of CPs based on the BDT donor unit and BDD and TT as acceptor units, respectively. A maximum power factor (PF) over 155 (142.7 ± 12.7) µW m−1 K−2, coupled with S ≈202 (194.6 ± 7.6) µV K−1 is achieved, leading to up to 32‐fold enhancement of the PF compared to the initial non‐planar and non‐fluorinated polymer. This study provides valuable conceptual insights for designing CPs with high conductivity and Seebeck coefficient.

Fluorine, the tiny robust atom, with its unique features has captured the attention of scientists in recent times, especially in drug discovery with its integration in small molecules, peptides, and proteins. However, studies to understand the 'fluorine effects' on the conformation of molecules that follow 'beyond the rule of 5' are in the infancy yet significant in molecular design and function. For the first time, using short hybrid peptide sequence as an appropriate model, we examined the substitution effect (size, stereoelectronic effect, and hydrogen bonding) using X‐ray diffraction, 2D‐NMR, and CD studies. The comparative study on their folding patterns with hydrogen‐substituted analogs can provide valuable insights into fluorinated substrates' design. [ABSTRACT FROM AUTHOR]

Herein, we characterized vacuum-evaporated thin-films of several new naphthalene tetracarboxylic diimide derivatives (C12-NTCDI-R) as n-type organic thin-film transistor (TFT) materials. They have head and tail structure with dodecyl chain and phenylalkyl (benzyl or phenylethyl) groups. By introducing fluorine groups into the phenylalkyl groups, the electron transport properties were enhanced. In addition, modifying the substrate surfaces with a fluorine-rich polymer material and annealing at the appropriate temperature allowed the TFT devices with C12-NTCDI-F2Bn (R = 3,5-difluorobenzyl) to reach a maximum electron mobility (μ e) of 0.11 cm2 V−1 s−1. Furthermore, the alteration of the number of methylene carbons in the side chain of phenylalkyl groups in C12-NTCDI-R (namely, phenylethyl was used as R) affected the thermal behavior of their molecules during the thin-film formation. For the TFT device with C12-NTCDI-PhEt (R = phenylethyl), the μ e reached the maximum value of 0.16 cm2 V−1 s−1 by just surface modification, without annealing. [ABSTRACT FROM AUTHOR]

Cation-disordered rocksalt (DRX) oxides are a promising new class of high-energy-density cathode materials for next-generation Li-ion batteries. However, their capacity fade presents a major challenge. Partial fluorine (F) substitution into the oxygen (O) lattice appears to be an effective strategy for improving the cycling stability, but the underlying atomistic mechanism remains elusive. Here, using a combination of advanced transmission electron microscopy based imaging and spectroscopy techniques, the structural and chemical evolution upon cycling of Mn-based DRX cathodes with an increasing F content (Li-Mn-Nb-O-Fx , x = 0, 0.05, 0.2) are probed. The atomic origin behind the beneficial effect of high-level fluorination for enhancing the surface stability of the DRX is revealed. It is discovered that, due to the reduced O redox activity while with increasing F concentration, F in the DRX lattice mitigates the formation of an O-deficient surface layer upon cycling. For low F-substituted DRX, the O loss near the surface results in the formation of an amorphous cathode-electrolyte interphase layer and nanoscale voids after extended cycling. Increased F concentration in the DRX lattice minimizes both O loss and the interfacial reactions between DRX and the liquid electrolyte, enhancing the surface stability of DRX. These results provide guidance on the development of next-generation cathode materials through anion substitution.

Hybrid organic−inorganic metal halides (HOMHs) have emerged as an ideal platform for the construction of semiconductor materials with promising optoelectronic properties. A number of HOMHs based on different metals including Sb3+ have been demonstrated with second‐harmonic generation (SHG) properties, but their nonlinear optical (NLO) performances including effective conversion wavelength range, optical stability, and NLO coefficients are not yet satisfactory. Here, by adopting a molecular design involving fluorine‐substitution on the achiral organic ammonium, this work has synthesized single crystals of two new chiral noncentrosymmetric HOMHs, (2‐FPEA)2SbX5 (X = Cl and Br), with large polarization ratios and outstanding optical transparency. The second‐order NLO coefficients of (2‐FPEA)2SbCl5 and (2‐FPEA)2SbBr5 are determined to be ≈24.3 and 21.6 pm V−1. Significantly, the Sb3+‐based HOMHs enable very high thermal stability and laser resistance. The distinguished laser‐induced damage thresholds (LDTs) have been estimated to be as high as 3.44 mJ cm−2 for (2‐FPEA)2SbCl5 and 3.32 mJ cm−2 for (2‐FPEA)2SbBr5, higher than that of the reported HOMHs. Such a highly efficient SHG performance and stability indicate the promising future of these Sb3+‐based metal halides for nonlinear photonic applications. [ABSTRACT FROM AUTHOR]

We propose the improvement of de/rehydrogenation kinetics and reversibility of LiNH 2 –LiH system via F substitution for H in LiNH 2. Slight content of LiF–TiH 2 composite is milled with LiNH 2 –3LiH and the obtained mixture is compacted into the pellet. By compositing LiNH 2 with excess LiH and compaction, NH 3 emission poisoning fuel cell catalysts and degrading hydrogen capacity can be prevented. The formation of LiNH (2-x) F x achieved from F substitution in LiNH 2 significantly enhances kinetic properties, for example, the 1st dehydrogenation at 280 °C completes within 5 min with the capacity of 3.6 wt % H 2. Although LiNH (2-x) F x cannot be recovered, good kinetics and reversibility upon five de/absorption cycles of LiNH 2 –LiH (up to 3.0 wt % H 2 within 20 min) are preserved due to catalytic effects of LiF. Phase compositions and hydrogen capacities in laboratory and tank scales are comparable. This suggests the maintained de/rehydrogenation performance of Li–N–F–H pellets even after upscaling. [Display omitted] • Kinetic improvement via F substitution for H in LiNH 2 is for the first time studied. • LiNH (2-x) F x -LiH shows superior dehydrogenation kinetics. • LiF-catalyzed LiNH 2 –LiH is responsible for excellent reversible capacities and kinetics. • NH 3 emission upon cycling of LiNH (2-x) F x /LiNH 2 –LiH system is suppressed. • Upscaling LiNH (2-x) F x /LiNH 2 –LiH system to small hydrogen storage tank is done. [ABSTRACT FROM AUTHOR]

In recent years, due to the rapid development of high-performance small molecule acceptor (SMA) materials, the researches on p-type electron donor materials for matching with current efficient SMAs have become important. By means of asymmetric strategies to optimize the energy levels and inter/intramolecular interactions of molecules, we designed and synthesized an asymmetric aromatic side chain quinoxaline-based polymer donor TPQ-0F. Meanwhile, we took advantage of F atom which could form noncovalent interaction and strong electron-withdrawing property, to obtain the optimized quinoxaline-based polymer donors TPQ-1F, TPQ-1Fi and TPQ-2F. Eventually, the binary device based on TPQ-2F achieved an efficient power conversion efficiency (PCE) of 16.27%, which attributed to balanced hole/electron mobilities, less charge carrier recombination, and more favorable aggregation morphology. Our work demonstrates the great potential of asymmetric aromatic side chain quinoxaline-based polymer donors on optimizing the morphology of blending films, improving inter/intramolecular interactions, and subtly tuning energy level, finally for more efficient organic solar cells. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The fluorine substitution position in organic semiconductors is critical in improving device performance for organic solar cells (OSCs). Herein, two similar small‐molecule donors, B3T‐PoF and B3T‐PmF, are designed and synthesized, which only differ on the fluorine substitution position on the pendent benzene unit. Although both small‐molecule donors exhibit similar absorption profiles and molecular energy levels, B3T‐PmF has stronger crystallinity and lower energetic disorder than B3T‐PoF. After blending with the non‐fullerene acceptor of BO‐4Cl, B3T‐PmF shows better phase separation and more ordered molecular packing in blend film. As a result, the B3T‐PoF:BO‐4Cl‐based OSC shows a power conversion efficiency (PCE) of 12.3%. In contrast, the B3T‐PmF:BO‐4Cl‐based cell demonstrates obviously increased JSC and FF values, thus yielding an excellent PCE of 14.7%. This study indicates that reasonable selection of fluorine atom substitution position in conjugated side chains is one of the promising strategies for achieving high‐performance SM‐OSCs. [ABSTRACT FROM AUTHOR]

Brucite [Mg(OH)2] has been extensively studied as a simple yet important analog for studying physical and chemical properties of hydrous minerals, and fluorine substitution (OH– = F–) is common in hydrous minerals since the radius of F– is similar to that of O2−. We synthesized two F-bearing brucite samples, Mg(OH)1.78F0.22 and Mg(OH)1.16F0.84, at 9.5 GPa and 1373 K. Single-crystal X‑ray diffraction measurements indicate that both phases still crystallize in the space group of P3m1, and fluorine substitution significantly reduces the unit-cell volume, axial lengths, and averaged Mg-O(F) bond lengths. The averaged O···H distances get slightly shortened, and the H-O-H angles become smaller due to the fluorine efect. Additional IR-active OH-stretching bands are observed at 3660, 3644, and 3513 cm−1 for the F-bearing samples, besides the original one at 3695 cm−1. In situ high-temperature and high-pressure Raman and Fourier transform infrared (FTIR) spectra were collected on the F-bearing brucite samples, and comparisons were made with the natural one with 0.7 mol% F–. The temperature dependence [(∂vi/∂T)P] of the OH-stretching modes is inversely correlated to the vibrational frequencies from 3500 to 3700 cm−1, whereas (∂vi/∂P)T is in positive correlation with vi. In addition, the dehydration temperatures of the F-bearing brucites are 100–150 K higher than that for the F-free sample at ambient pressure. By creating new proton positions in lower energies, fluorine substitution stabilizes hydrous minerals (like brucite) to higher temperatures and significantly affects their thermodynamic properties, which has significant implications in mineral physical and geochemical studies. [ABSTRACT FROM AUTHOR]

Adopting a ternary strategy is an effective approach to enhance the power conversion efficiency (PCE) in organic solar cells (OSCs). Previous research on highly efficient ternary systems has predominantly focused on those based on highly crystalline dual small molecule acceptors. However, limited attention has been given to ternary systems utilizing dual polymer donors. Herein, by incorporating the fluorine and alkylsilyl substitution, a new polymer donor named PX1 is developed, which demonstrates strong crystallinity and excellent miscibility with polymer PM6. Moreover, PX1 broadens and enhances the absorption properties of the PM6:L8-BO blends, and its molecular orbital energy level is situated between those of PM6 and L8-BO, highlighting its suitability as a third component. Introducing 20% PX1 into the PM6:L8-BO system resulted in a high PCE of 18.82%. PX1 effectively suppresses charge recombination and reduces energy losses, while also serving as a morphology modulator that enhances the crystallization and improves the molecular packing order of the active layer by shortening the π-π stacking distance and extending crystalline coherence length. These factors collectively contribute to the performance improvements in ternary devices. This study demonstrates that employing a dual polymer donor strategy is a promising approach for achieving high-performance ternary OSCs., (© 2024 Wiley‐VCH GmbH.)

Fluorine substitution was applied to the donor and acceptor segments of block copolymers to understand the impact of molecular structure on photovoltaic block copolymers and explore efficient materials for single-component organic solar cells (SCOSCs). Along this line, three fluorinated block copolymers, namely PBDB-T-b-PTYF6, PM6-b-PTY6, and PM6-b-PTYF6, derived from PBDB-T-b-PTY6 were designed and synthesized. The UV–Vis absorption, energy level, and thin-film morphology of these block copolymers were systematically characterized. All fluorinated block copolymers show narrow bandgap and improved crystallinity. An enhanced open-circuit voltage was observed in the SCOSC based on PM6-b-PTY6. However, SCOSCs based on all fluorinated block copolymers exhibited low short-circuit current due to energy level mismatch and therefore had low power conversion efficiency at around 4%. By contrast, the SCOSCs based on control block copolymer PBDB-T-b-PTY6 exhibited the highest power conversion efficiency approaching 10%, with a high short-circuit current of 18.57 mA/cm2. Our study was the first to perform fluorination on photovoltaic block copolymers and provides insight into precisely controlling the polymer structure and understanding the structure–property relationship in SCOSCs based on block copolymers. [ABSTRACT FROM AUTHOR]

The recent development of flexible display technology raised additional requirements for optical and electric properties of polyimides, accelerating the structure and property tunning of transparent polyimides. The unique electronic effect and steric hindrance effect of fluorine substitutions make fluorine-containing polyimides occupy an important position in the transparent polyimide family. In this work, a series of transparent aromatic polyimides were prepared from a fixed 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and biphenyl diamines with different substitute groups at the 2,2′,6,6′-positions. We systematically studied the effects of pendant groups on the thermal, mechanical, optical and dielectric properties of these 6FDA-based polyimides with the aid of density function theory (DFT) calculation. In particular, we paid special attention to the simple but compact fluoro group substitution. The simple fluoro substitution brought the advantages of maintaining the linearity of the backbone and dense polymer chain packing, which would minimize the weakening of polyimides' inherent thermal, dimensional and mechanical properties. Comparing with trifluoromethyl substituted polyimides with the best optical transparency, polyimides containing fluoro substitutes exhibited slightly decreased optical transparency, but increased thermal and dimensional stability and higher mechanical strength. These results could shed light on the ultimate transparent polyimide film development toward the application in extreme working condition, e.g., the colorless polyimide substrate film for the flexible display technology. [ABSTRACT FROM AUTHOR]

Low cost, high efficiency, and high stability are the three key issues of organic solar cells (OSCs) that should be carefully considered to meet the requirement of future commercial applications. Therefore, the development of high‐performance organic photovoltaic materials with low synthetic cost has been becoming a crucial challenge in the field of OSCs. Herein, two new low‐cost small‐molecule donors (SM‐BF1 and SM‐BF2) are designed and synthesized with a facile synthetic route by replacing 4‐bromo‐2‐fluorobenzenethiol and 4‐bromo‐3‐fluorobenzenethiol with low‐cost 4‐bromo‐2‐fluoro‐1‐iodobenzene and 4‐bromo‐3‐fluoro‐1‐iodobenzene as key raw materials. Besides, the influence of the chemical steric effect of the phenyl conjugated side chains of the benzodithiophene (BDT) unit on photophysical properties, charge transfer, and photovoltaic properties are deeply investigated by the modulation of fluorine atom substituted position. As a result, SM‐BF1 with ortho‐fluorinated substituent has outstanding crystallization properties and better miscibility with acceptor Y6 and exhibits more desirable morphology and more balanced charge‐carrier transport properties, leading to a superior power conversion efficiency (PCE) to 15.71%. More encouragingly, according to the figure of merit (FOM) and the industrial figure of merit (i‐FOM) to evaluate the small‐molecule donors, the SM‐BF1‐based device has excellent potential for future commercial applications. [ABSTRACT FROM AUTHOR]

In this contribution, we studied the effect of fluorine substitution on photogenerated charge generation, transport, and recombination in polymer solar cells. Two conjugated polymer materials, PBDTTT-E (fluorine free) and PTB7 (one fluorine substitution), were compared thoroughly. Meanwhile, various characterization techniques, including atomic force microscopy, steady-state spectroscopy, transient absorption spectroscopy, spectroelectrochemistry, and electrical measurements, were employed to analyse the correlation between molecular structure and device performance. The results showed that the influence of fluorine substitution on both the exciton binding energy of the polymer and the carrier recombination dynamics in the ultrafast timescale on the polymer was weak. However, we found that the fluorine substitution could enhance the exciton lifetime in neat polymer film, and it also could increase the mobility of photogenerated charge. Moreover, it was found that the SOMO energy level distribution of the donor in a PTB7:PC71BM solar cell could facilitate hole transport from the donor/acceptor interface to the inner of the donor phase, showing a better advantage than the PBDTTT-E:PC71BM solar cell. Therefore, fluorine substitution played a critical role for high-efficiency polymer solar cells.

All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replacing the anion with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine into Li3YCl6 solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge–discharge characteristics were studied. The trace amounts of fluorine in Li3YCl6 did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge–discharge efficiency of the uncoated LiCoO2 cathode was improved by the trace amount of fluorine replacement in the Li3YCl6 solid electrolyte.

Organic solar cells based on narrow bandgap small-molecule acceptors (SMAs) with highly crystalline characteristics have attracted great attentions for their superiority in obtaining high photovoltaic efficiency. Employing highly crystalline SMAs to enhance power conversion efficiencies (PCEs) by regulating and controlling morphology and compatibility of donor and acceptor materials has turned out to be an effective approach. In this study, we synthesized three different crystalline SMAs by using fluorine substitution on alkoxyphenyl conjugated side chains to modulate the relationship of crystallinity and morphologies, namely ZY1 (zero F atoms), ZY2 (two F atoms), and ZY3 (four F atoms). The three SMAs show the broad absorption edges and similar frontier orbital energy levels, generating the analogical (over 0.9 ​V) open circuit voltage (VOC) of the polymer solar cells (PSCs). As a result, the PM6:ZY2-based PSCs yield a PCE of 10.81% with a VOC of 0.95 ​V, a short-circuit current density (JSC) of 16.154 ​mA ​cm−2, and a fill factor (FF) of 0.71, which is higher than that of 9.17% (PM6:ZY1) and 6.37% (PM6:ZY3). And the PCE (17.23%) of the PM6:Y6:ZY2 based ternary PSCs is also higher than that of 16.32% PM6:Y6 based binary device. Obviously, the results demonstrate that adding fluorine atoms on the conjugated side chains to construct high crystalline materials is a positive strategy to effectively increase the efficiencies of binary and ternary PSCs.

Recently, organic fused-ring compounds have made a breakthrough in the field of organic solar cells. In this paper, two A-D-AT)-A conjugated small molecules fused-ring compounds BT)T)-TC and BT)T)-TC4F with Benzo-l 2-c: 4 5-c, H dithiophene-4 8-dione as the central core and dicyanindenone or difluorodicyanoindenonethe as terminal group are designed and synthesized by the strategy of non covalent bond. The photophysical and electrochemical properties are studied by UV-Vis absorption spectroscopy, electrochemical cyclic voltammetry and density functional theory (T)FT) calculation. At the same time, the two small molecules are used as acceptors to fabricate all-small molecule solar cells, and their photovoltaic characteristics are studied. The results show that the fluorinated small molecule BDD-TC4F has wider optical absorption, deeper HOMO and LUMO levels and higher thermodynamic stability than BT)T)-TC, and the photovoltaic device based on BDD-TC4F also achieves ().21 % photoelectric conversion efficiency. [ABSTRACT FROM AUTHOR]

Spinel-type LiNi 0.5 Mn 1.5 O 4 (LNMO) can provide high-voltage and high theoretical specific capacity as cathode material for lithium-ion batteries (LIBs), thereby LNMO is particularly suitable for electric/hybrid electric vehicles that require high power. Unfortunately, both serious structural deformation derived from the Jahn-Teller effect of Mn3+ and decomposition of electrolyte during repetitive charge/discharge processes at high operating potential result in fast capacity fade. In this work, lanthanum and fluorine co-doping LiNi 0.5 La 0.01 Mn 1.49 O 3.97 F 0.03 (LF-LNMO) is proposed to eliminate its inherent defects. Fluorine can suppress Jahn-Teller effect of Mn3+ by reducing the generation of Mn3+; La3+ ions in LF-LNMO play a role in solidly riveting atoms together in the structure, and LaMnO 3 coating layer acts as a physical protection barrier suppressing adverse side reactions that may damage battery performance. Thanks to the synergistic effect derived from structural modification of F−, the pinning effect of La3+ ions, and LaMnO 3 surface coating interface reconstruction, the LF-LNMO cathode provides the best cycling performance and rate performance among all investigated electrode materials. Such as, LF-LNMO cathode can provide 64.02% capacity retention after the 1000th cycle at 500 mA g−1 and 30 °C, which is much higher than that (25.56%) of the undoped LiNi 0.5 Mn 1.5 O 4 (P-LNMO). Besides, LF-LNMO electrode also behaves the excellent high-temperature cycling performance. This work provides a new strategy enhancing structural stability of spinel-type Ni/Mn-based oxide and would motivate us to further devise and prepare high power cathode materials for LIBs. [Display omitted] • Spinel-type LiNi 0.5 La 0.01 Mn 1.49 O 3.97 F 0.03 (LF-LNMO) was synthesized by solid-state reaction at room temperatures. • La3+ doping plays a pinning effect role in improving the structural stability of LNMO. • F− doping can suppress Jahn-Teller effect of Mn3+ by reducing the generation of Mn3+. • LaMnO 3 coating layer can suppress adverse side reactions that may damage battery performance. • LF-LNMO can provide the excellent cycling performance and rate capability. [ABSTRACT FROM AUTHOR]

The effect of fluorine substitution on the hydrogen bonding interaction in the complexes of fluorosubstituted pyridines and acetic acid was examined through theoretical method. Two types of double hydrogen bonding cyclic structures have been predicted, one with O–H···N and C–H···O interactions and the other with O–H···F and C–H···O interactions. The changes of the hydrogen bonding interactions are visualized by the reduced density gradient (RDG) and bond critical point (BCP) parameters analysis. With increasing in fluorination, the C–H···O bond strength increases, and the O–H···N and O–H···F bond strengths decrease. Although the O–H···N and O–H···F hydrogen bond energies decrease, the bond type has not changed in all of the fluorinated complexes. For the same degree of fluorination complexes, fluorine favors the C–H···O hydrogen bonding interaction through the cooperating of O–H···F and C–H···O hydrogen bonds, although fluorine is a weak hydrogen bond acceptor. The natural population analysis (NPA) and molecular electrostatic potentials (ESP) were adopted to further explore the variation characteristics of hydrogen bond strength. We found that the substituent fluorine atom acts as a role of electron withdrawing. The pyridine ring nitrogen atom and 2‐position fluorine atom become less negative, and the remaining H atom(s) become more electropositive with increasing degree of fluorination. The hydrogen bond strength is correlated with the charge redistribution of the proton H and acceptor (N and F) atoms. [ABSTRACT FROM AUTHOR]

Structural analysis of modern pharmaceutical practices allows for the identification of two rapidly growing trends: the introduction of tailor‐made amino acids and the exploitation of fluorinated motifs. Curiously, the former represents one of the most ubiquitous classes of naturally occurring compounds, whereas the latter is the most xenobiotic and comprised virtually entirely of man‐made derivatives. Herein, 39 selected compounds, featuring both of these traits in the same molecule, are profiled. The total synthesis, source of the corresponding amino acids and fluorinated residues, and medicinal chemistry aspects and biological properties of the molecules are discussed. [ABSTRACT FROM AUTHOR]

To investigate the effect of fluorine substitution on tolbutamide (TB) hydroxylation catalyzed by CYP2C9, the hydroxylation of TB and its fluorinated derivative 3'-fluoro-tolbutamide (3'-FTB) by recombinant human CYP2C9*1, CYP2C9*2, and CYP2C9*3 was analyzed. In general, fluorine substitution near the metabolic site may decrease enzymatic oxidation owing to its electron-withdrawing nature. Fluorine substitution reduced the Michaelis-Menten-derived Km of 4'-hydroxylation of TB catalyzed by CYP2C9*1 from 115 (TB) to 77 (3'-F-TB) µM. In the case of TB hydroxylation catalyzed by CYP2C9*2, the Km value of TB was also reduced by fluorine substitution from 129 to 88 µM. The greatest effect of fluorine substitution on the Km in TB hydroxylation was observed in the catalysis by CYP2C9*3, in which the Km value decreased from 287 to 117 µM. When a mixture containing TB and 3'-F-TB was hydroxylated by CYP2C9, the hydroxylated metabolite ratio in CYP2C9*3 was significantly increased compared with that in CYP2C9*1 and CYP2C9*2 (p < 0.01, Tukey-Kramer test). These results suggest that obtaining the metabolite profiles of fluorine-substituted analogs of the key substrate molecule may be useful as a new tool for phenotyping polymorphic CYP isoforms. [ABSTRACT FROM AUTHOR]

Bone supports animal bodies, is the place where blood is produced, and is essential for the immune system, among other important functions. The dominant inorganic component in bone is hydroxyapatite (Hap), the structure and dynamics of which still pose many unsolved puzzles. An updated understanding of HAp is of great significance to osteology, dentistry, and the development of artificial bone and other biomaterials. In this work, HAp nanoparticles were synthesized with the wet chemical precipitation method and their structure and morphologies were controlled by varying pH and adding fluoride ions by two different routes: (1) fluoride ions were added during synthesis, and (2) fluoride ions were introduced after the samples were synthesized by soaking the samples in solutions with fluoride ions. XRD and HRTEM were employed to confirm the composition and structure, while various multinuclear (1H, 19F, 31P) solid-state nuclear magnetic resonance (NMR) methods including 1D single pulse, cross-polarization under magic-angle spinning (CPMAS), and 2D heteronuclear correlation (HETCOR) were used to characterize the structure, morphology, and dynamics, validating the general core-shell morphology in these F-HAp samples. It was found that all hydroxide ions were substituted when the fluoride ion concentration was above 0.005 M. An NMR peak corresponding to water structure emerged and the bulk water peak was shifted upfield, indicating that fluoride substitution modifies both the crystalline core and the amorphous shell of F-HAp nanoparticles. With the second route of fluoride substitution, increases in soaking time or fluoride ion concentration could increase fluoride substitution in HAp, but could not achieve complete substitution. Finally, with 1H-31P CPMAS and HETCOR, it was established that there are two types of phosphorous, one in the crystalline core (PO43−) and the other in the amorphous shell (HPO42−). These results are valuable for clarifying the fluoride substitution mechanism in HAp in biomaterials or in organisms, and provide insights for developing next generation replacement materials for bone, tooth, or coating films, drug delivery systems, etc.

The interaction of oxygen and fluorine (F&O) in an F-doped SnO2 film, prepared by regulating oxygen partial pressure and the content of doped fluorine from 2.5 at% to 10 at%, was investigated in the large perspective through characterization methods including XRD, Raman spectroscopy, photoluminescence spectroscopy, wettability measurement and a Hall effect test system. The results show that F&O’s competitive and cooperative relationship would be reflected in the structure and electrical characteristics of SnO2 films. The oxygen action is overwhelming and restricts fluorine, so a growing number of F atoms occupy the position by the order of co-edge oxygen of tin–oxygen octahedron chains > oxygen vacancies > segregation, which leads to that carrier concentration modestly increasing from ~1015 to ~1017/cm−3. As oxygen action is inadequate to restrain fluorine, more F atoms are likely to enter the SnO2 lattice in a solid-solution way to replace the O atoms at the co-edge position of the octahedron chains, causing a dramatic increase in carrier concentration from ~1016 to ~1019/cm−3. Furthermore, by continuing to weaken oxygen action, only 2.5 at% of fluorine content could bring about a carrier concentration augment from ~1016/cm−3 to ~1018/cm−3, then going up to ~1021/cm−3 by post-annealing. However, the impairment of oxygen action contributes to a more effective doping of fluorine on SnO2 film. Such mutual action between fluorine and oxygen provides a direction for highly efficient production and tunable regulation of SnO2 film on demand.

Dye that is consisting of donor-π-π-linkers-acceptor (D-π-π-A) is characterised by enhancement of light-harvesting capability in dye-sensitised solar cell (DSSC) applications. In this work, the DFT and TDDFT using the CAM-B3LYP XC-functional with 6-31G+(d) basis set and were used to study the geometrical, electronic, and photovoltaic properties of four dyes. Two of the investigated dyes are previously reported as successful photosensitisers with power conversion efficiencies of 8.22 and 7.0%, and two are novel designed ones. The investigated dyes are based on triphenylamine (TPA) as electron-donor and cyanoacrylic acid (CA) as electron-acceptor groups, and two π-linkers, i.e. dihydrothieno-dioxine (DHO) and fluorophenylene (FP). The four dyes are different in the FP unit which has Fluorine (F) atom/s in different position and with a different number. The study aims to: (1) justify the reported superiority performance of T2FC (with one F atom at the ortho-position with respect to the CA unit) over the T3FC (with one F atom at the meta-position), and (2) explore the effect of incorporating another F atom at the second ortho-position (T26FC) or at the meta-position (T35FC). The results are supported by the data obtained from calculations of adsorption parameters of dyes adsorbed on (TiO2)24 anatase (1 0 1). [ABSTRACT FROM AUTHOR]

Herein, we fabricated all-polymer solar cells (all-PSCs) based on a fluorinated wide-bandgap p-type conjugated polymer PM6 as the donor, and a narrow bandgap n-type conjugated polymer PZ1 as the acceptor. In addition to the complementary absorption and matching energy levels, the optimized blend films possess high cystallinity, predominantly face-on stacking, and a suitable phase separated morphology. With this active layer, the devices exhibited a high Voc of 0.96 V, a superior Jsc of 17.1 mA cm-2, a fine fill factor (FF) of 68.2%, and thus an excellent power conversion efficiency (PCE) of 11.2%, which is the highest value reported to date for single-junction all-PSCs. Furthermore, the devices showed good storage stability. After 80 d of storage in the N2-filled glovebox, the PCE still remained over 90% of the original value. Large-area devices (1.1 cm2) also demonstrated an outstanding performance with a PCE of 9.2%, among the highest values for the reported large-area all-PSCs. These results indicate that the PM6:PZ1 blend is a promising candidate for scale-up production of large area high-performance all-PSCs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The F- Bi 2 MoO 6 can be easily synthetized by a hydrothermal method. • F- Bi 2 MoO 6 show much higher photocatalytic activity than pure Bi 2 MoO 6. • F doing can increase the band gap of Bi 2 MoO 6 and concentration of OH radicals. • The enhanced photocatalytic activity is due to higher charge separation efficiency. Abstract The fluorine substitution on Bi 2 MoO 6 (F-Bi 2 MoO 6) can be easily synthesized by a hydrothermal method. Based on the XRD result, it could be speculated that fluorine ion can substitute oxygen ion in the crystal lattice of Bi 2 MoO 6. The photodegradation activity of F-Bi 2 MoO 6 almost is 1.9 times as high as the single Bi 2 MoO 6 for degradation of RhB and 1.7 times for decomposition of 2, 4-CDP under the visible light. The enhanced catalytic activity of F-Bi 2 MoO 6 should be attributed to the wider band gap, the more positive VB potential and the higher concentration of OH radicals due to the F doping. Additionally, F doping formed the donor state below the Fermi energy, which can trap the electrons and increase the efficiency of charge separation remarkably. [ABSTRACT FROM AUTHOR]

Layered potassium manganese oxides (K x MnO 2) have been widely investigated as potential cathode materials for K-ion batteries owing to their high capacity and low material cost. However, the K x MnO 2 cathodes generally suffer from unsatisfactory cycle life due to Mn dissolution into the electrolyte triggered by acidic HF corrosion and structural stress at the particle surface during cycling. In this study, we introduce an efficient strategy to stabilize the aggressive chemistry between the organic electrolyte solution and the P′3-type K 0 · 6 MnO 2 (KMO) cathode surface through fluorine treatment. KF-coated P′3-type K 0.6 MnO 1.97 F 0.03 (KMOF-7) is prepared by introducing 7 mol% of ammonium fluoride (NH 4 F) during a pyro-synthesis of K 0 · 6 MnO 2. The partial substitution of F to oxygen atom narrows the interlayer spacing, which helps to reduce the insertion of electrolyte molecules into the crystal structure; meanwhile, the formation of KF coating layer on the cathode surface can suppress the Mn dissolution by protecting KMOF-7 from reacting with HF in the electrolyte solution during charge–discharge processes. This strategy can relieve the structural stress and stabilize the interfacial stability of KMOF-7, thereby, facilitating K+ transportation and depress the charge transfer resistance upon cycling. The KMOF-7 cathode demonstrates the significantly improved cycling stability and power capability compared to KMO. [Display omitted] • Simple NH 4 F treatment enhances the structural and interfacial stability of K 0 · 6 MnO 2. • The partial substitution of F to O atom enhances the structural stability of cathode. • The KF coating layer on the cathode surface can suppress the Mn dissolution. [ABSTRACT FROM AUTHOR]

Two benzothiadiazole (BT)-based small-molecule donors, SM-BT-2OR with alkoxy side chain and SM-BT-2F with fluorine atom substitution, were designed and synthesized for investigating the effect of the substituents on the photovoltaic performance of the donor molecules in all small molecule organic solar cells (SM-OSCs). Compared to SM-BT-2OR, the film of SM-BT-2F exhibited red-shifted absorption and deeper HOMO level of −5.36 eV. When blending with n-type organic semiconductor (n-OS) acceptor IDIC, the as-cast devices displayed similar PCE values of 2.33 and 2.76% for the SM-BT-2OR and SM-BT-2F-based devices, respectively. The SM-BT-2OR-based devices with thermal annealing (TA) at 120°C for 10 min showed optimized PCE of 7.20%, however, the SM-BT-2F-based device displayed lower PCE after the TA treatment, which should be ascribed to the undesirable morphology and molecular orientation. Our results reveal that for the SM-OSCs, the substituent groups of small molecule donors have great impact on the film morphology, as well as the photovoltaic performance.

Abstract Incorporating fluorine into liquid crystalline molecules has been found to bring about desirable changes to their physicochemical properties to improve the behavior of the parent compound. This paper attempts to determine the effect of fluorine incorporation on refractive indices in biphenyl-cyclohexane (BCH) liquid crystals. To understand the mechanisms of the effect, quantum chemistry calculations were carried out. For the investigated liquid crystals, refractive indices are estimated through the calculated molecular polarizabilities at different optical wavelengths. Through a systematic relationship between the fluorine substituents and the optical constants, it has been demonstrated that the refractive indices of the investigated liquid crystals do not change largely in the studied wavelength range. However, the fluorine substituents significantly affect refractive indices. The effects of fluorine substitution on the core geometry are also examined. Graphical abstract Unlabelled Image Highlights • Stereoselective fluorination is an effective tool in modulating the LC properties. • In BCH LCs, there is no significant effect of wavelength on the refractive indices. • Contrarily, the fluorine substitution strongly influences the refractive indices. [ABSTRACT FROM AUTHOR]

A high performance polymer solar cells (PSCs) based on polymer donor PM6 containing fluorinated thienyl benzodithiophene unit and n-type organic semiconductor acceptor IT-4F containing fluorinated end-groups were developed. In addition to complementary absorption spectra (300-830 nm) with IT-4F, the PM6 also has a deep HOMO (the highest occupied molecular) level (−5.50 eV), which will lower the open-circuit voltage (Voc) sacrifice and reduce the Vloss of the IT-4F-based PSCs. Moreover, the strong crystallinity of PM6 is beneficial to form favorable blend morphology and hence to suppress recombination. As a result, in comparison with the PSCs based on a non-fluorinated D/A pair of PBDB-T:ITIC with a medium PCE of 11.2%, the PM6:IT-4Fbased PSCs yielded an impressive PCE of 13.5% due to the synergistic effect of fluorination on both donor and acceptor, which is among the highest values recorded in the literatures for PSCs to date. Furthermore, a PCE of 12.2% was remained with the active layer thickness of up to 285 nm and a high PCE of 11.4% was also obtained with a large device area of 1 cm2. In addition, the devices also showed good storage, thermal and illumination stabilities with respect to the efficiency. These results indicate that fluorination is an effective strategy to improve the photovoltaic performance of materials, as well as the both fluorinated donor and acceptor pair-PM6:IT-4F is an ideal candidate for the large scale roll-to-roll production of efficient PSCs in the future. [ABSTRACT FROM AUTHOR]

Although fluorine-contained polymers have been adopted in efficient polymer solar cells, complicated reaction methods and costly fluorination reagents have impeded large-scale application. Here, a novel fluorinated polymer donor, PM6-F , was designed and synthesized via a newly developed 3-fluoro-2-iodithiophene to simplify synthesis procedures and minimise reaction costs from modest raw materials. Compared with the polymer analogue PM6 without any fluorine substituent on the main chain, it was found that PM6-F with a better configuration exhibited more orderly molecular packing, stronger and broader absorption, a narrower optical band gap, and a lower-lying HOMO energy level. The PM6-F :IT-4F-based PSCs obtained an excellent PCE of 14.90% with a V OC of 0.91 V, a J SC of 23.25 mA cm−2, and an FF of 70.42%. Notably, the value of 14.90% was among the highest recorded in the literature for IT-4F-based PSCs. This research demonstrated that modifying π-bridges with fluorine is a promising strategy for developing high-efficiency polymer donors. [Display omitted] • ●We reported a new fluorinated polymer, PM6-F , as the donor material for PSCs. • ●We used a simpler approach to shorten the synthetic route and lower costs. • ●Compared with the analogue PM6, PM6-F has better photovoltaic characteristics. • ●The PM6-F :IT-4F-based PSCs obtained an excellent PCE of 14.90%. • ●The 14.90% value was among the highest ever recorded for IT-4F-based binary PSCs. [ABSTRACT FROM AUTHOR]

Catalytic fields illustrate topology of the optimal charge distribution of a molecular environment reducing the activation energy for any process involving barrier crossing, like chemical reaction, bond rotation etc. Until now, this technique has been successfully applied to predict catalytic effects resulting from intermolecular interactions with individual water molecules constituting the first hydration shell, aminoacid mutations in enzymes or Si→Al substitutions in zeolites. In this contribution, hydrogen to fluorine (H→F) substitution effects for two model reactions have been examined indicating qualitative applicability of the catalytic field concept in the case of systems involving intramolecular interactions. [ABSTRACT FROM AUTHOR]

The in vitro inhibition potency against acetylcholinesterase (AChE) of fluorinated derivatives of CP-118,954 ( 1 ) has been shown to depend upon the position of aromatic fluorine (F) substitution on the N -benzyl moiety. Indeed, the meta -F-substituted compound 3 (IC 50 = 1.4 nM) shows similar potency with the parent compound 1 (IC 50 = 1.2 nM), whereas the ortho -F derivative 2 (IC 50 = 3.2 nM) and para -F derivative 4 (IC 50 = 10.8 nM) were found to be less potent AChE inhibitors. A comparative in vivo microdialysis study in rats showed that 3 has the strongest effect on the neuropharmacological properties as AChE inhibitor. For PET imaging studies, a radiolabeled ligand ([ 18 F] 3 ) was synthesized through nucleophilic aromatic substitution reaction of diaryliodonium salt-based aldehyde precursor followed by reductive alkylation in a two-step radiolabeling procedure with 11.5 ± 1.2% ( n = 24, non-decay corrected) radiochemical yield and over 99% radiochemical purity. In a comparative PET imaging study of the three 18 F-containing derivatives of CP-118,954 ([ 18 F] 2 – 4 ), [ 18 F] 3 showed the highest radioactivity in the AChE-rich region of normal rat brain which visually reflected the in vitro AChE-binding affinity of 3 . These findings support [ 18 F] 3 as a promising AChE-targeted PET imaging ligand for the assessment of cholinergic activity into the brain, providing also insights into the AChE ligand disposition, which depends upon the position of the aromatic fluorine in the benzyl moiety. [ABSTRACT FROM AUTHOR]

Three low bandgap conjugated copolymers ( PB-DPP , PDFB-DPP , and PTFB-DPP ) based on 1,4-dithienylphenylene and diketopyrrolopyrrole units were synthesized and characterized as the donor materials for polymer solar cells. The effect of the number of fluorine atoms on thermodynamic, crystalline, physicochemical and photovoltaic properties of the copolymers was comparatively investigated. Results indicate that the absorption peaks of polymer solutions are blue-shifted and optical bandgaps are gradually decreased along with the increase of the number of fluorine atoms. Moreover, PDFB-DPP and PTFB-DPP show better light-harvesting abilities, higher crystallinities and lower-lying HOMO energy levels than those of PB-DPP . Photovoltaic performances of these copolymers were studied and optimized. PDFB-DPP and PTFB-DPP deliver a power conversion efficiency of 5.31% and 4.93%, respectively, both of which are higher than that of PB-DPP (4.13%) due to the increased J sc and V oc . This work demonstrates that the number of fluorine substitution is crucial to improving optoelectronic properties. [ABSTRACT FROM AUTHOR]

In order to reveal the effect of fluorine substitutions on the refractive index properties for calamitic nematic materials, we carried out a comparative study with respect to non-fluorinated and two types of laterally fluorinated 1,4-bis[4-(hexyloxy)phenyl]ethynylbenzene molecules. Phase transition behaviours were investigated by differential scanning calorimetry and polarised optical microscopy. Additionally, extraordinary and ordinary refractive index and birefringence were evaluated from each single component system. All the analogues exhibited high birefringence values beyond 0.3 at 550 nm, of which an analogue with a fluorine substitution at the central benzene ring showed the highest Δn-value of 0.43. With respect to an analogue with the highest level of fluorination, Δnas well asneandnovalues were declined due to decreased order parameter and diluted molecular density. Not only the mesomorphic behaviours but also optical properties strongly relied on the manner of fluorine substitution including the number and position. [ABSTRACT FROM AUTHOR]

Bicontinuous cubic phases are of significant importance for numerous applications, for example, for the crystallization of membrane proteins, as photonic materials and as templates for porous silica. A new variant of bicontinuous cubic liquid crystalline phase with Ia [ABSTRACT FROM AUTHOR]

Three types of semi-crystalline photovoltaic polymers were synthesized by incorporating a siloxane-terminated organic/inorganic hybrid side-chain and changing the number of fluorine substituents. A branch point away from a polymer main backbone in the siloxane-containing side-chains and the intra- and/or interchain noncovalent coulombic interactions enhance a chain planarity and facile interchain organization. The resulting polymers formed strongly agglomerated films with high roughness, suggesting strong intermolecular interactions. The optical band gap of ca. 1.7 eV was measured for all polymers with a pronounced shoulder peak due to tight π-π stacking. With increasing the fluorine substituents, the frontier energy levels decreased and preferential face-on orientation was observed. The siloxane-terminated side-chains and fluorine substitution promoted the intermolecular packing, showing well resolved lamellar scatterings up to (300) for this series of polymers in the grazing incidence wide angle X-ray scattering measurements. The PPsiDTBT, PPsiDTFBT and PPsiDT2FBT devices showed a power conversion efficiency of 3.16%, 4.40% and 5.65%, respectively, by blending with PCBM. Langevin-type bimolecular charge recombination was similar for three polymeric solar cells. The main loss in the photocurrent generation for PPsiDTBT:PCBM was interpreted to originate from the trap assisted charge recombination by measuring light-intensity dependent short-circuit current density ( J ) and open-circuit voltage ( V ). Our results provide a new insight into the rational selection of solubilizing substituents for optimizing crystalline interchain packing with appropriate miscibility with PCBM for further optimizing polymer solar cells. [ABSTRACT FROM AUTHOR]

In order to figure out the effects of terminal groups on phase transitions and birefringence, we performed a comparative study for non-fluorinated and centrally fluorinated liquid crystalline 1,4-bis(phenylethynyl)benzene molecules with the same tail length of heptyl, hexyloxy, hexylthio groups at both para positions. These molecules showed remarkable effects of the terminal groups to the phase transitions. The birefringence values at close temperatures, as well as an order parameter (S) = 1 for a fluorinated family, are in the following order of alkylthio > alkoxy > alkyl analogues, corresponding to their polarizabilities. [ABSTRACT FROM AUTHOR]

The high ionic conductivity and good oxidation stability of halide-based solid electrolytes evoke strong interest in this class of materials. Nonetheless, the superior oxidative stability compared to sulfides comes at the expense of limited stability toward reduction and instability against metallic lithium anodes, which hinders their practical use. In this context, the gradual fluorination of Li 2 ZrCl 6- x F x (0 ≤ x ≤ 1.2) is proposed to enhance the stability toward lithium-metal anodes. The mechanochemically synthesized fluorine-substituted compounds show the expected distorted local structure (M2-M3 site disorder) and significant change in the overall Li-ion migration barrier. Theoretical calculations reveal an approximate minimum energy path for Li 2 ZrCl 6- x F x ( x = 0 and 0.5) with an increase in the Li + migration energy barrier for Li 2 ZrCl 5.5 F 0.5 in comparison to Li 2 ZrCl 6 . However, it is found that the fluorine-substituted compound exhibits substantially lower polarization after 800 h of lithium stripping and plating owing to enhanced interfacial stability against the lithium metal, as revealed by density functional theory and ex situ X-ray photoelectron spectroscopy, thanks to the formation of a fluorine-rich passivating interphase.

[Display omitted] • Sodium-rich cathode with fluorine substitution at anion site strategy. • Beyond 78% capacity retention even after 500 cycles. • Performance outperforming Li-NCM811 at higher current density. • Improved sodium diffusion due to F-substitution at anion site. • Sodium cathode outperforming benchmark Lithium cathode (NCM 811). Among the various sodium cathodes, the potential of Na-rich layered oxides is yet to be fully utilized. Unlike their Li counterparts, they are least explored and are at least a generation behind in development. Addressing the same, herein, Na-rich Na x Mn 2- x O 1.5 F 0.5 (x = 1.05–1.3) type cathodes were synthesized successfully and analyzed as potential electrodes for Na-ion battery applications. Oxygen loss in Na-based transition metal oxides is a common issue, and it is effectively addressed by fluorine substitution. In contrast to exploring a particular stoichiometry as in other Na-deficient layered cathodes, herein, Na-content was gradually increased from 1.05 to 1.3. The cathodes were synthesized using a conventional solid-state approach and quenched to achieve high crystallinity. Compounds with different sodium stoichiometry were electrochemically tested in a half-cell configuration. Among these compounds, the Na 1.2 Mn 0.8 O 1.5 F 0.5 electrode exhibited very high capacities of 178 and 122 mAhg−1 at current densities of 10 and 1000 mA g−1, respectively. The Na-rich Na 1.2 Mn 0.8 O 1.5 F 0.5 cathode was systematically analyzed to understand the mechanism underlying its superior performance using various structural and electrochemical analyses. Furthermore, to demonstrate its practicality, the Na-rich Na 1.2 Mn 0.8 O 1.5 F 0.5 cathode was coupled with a hard carbon and Na-In alloy anode in a full-cell assembly. [ABSTRACT FROM AUTHOR]

A novel series of air-stable, fluorinated naphtho [2,1- b :3,4- b ′]bis [1]-benzothiophenes bearing various lateral alkoxy-substituents, NBBTF- n ( n = 8, 10, and 12) and its unsubstituted analogue, NBBT-10 were synthesized and investigated with field-effect transistor properties. Fluorine substitution affords desirable properties including high melting transition, high thermal stability and low-lying highest occupied molecular orbital (HOMO) energy levels for air-stable semiconductors. The OFET devices based on annealed NBBTF-10 films exhibit superior hole transport with mobility up to 0.35 cm 2 V −1 s −1 to that of NBBT-10, attributed to the close molecular stacking induced by fluorine substitution. [ABSTRACT FROM AUTHOR]

Structural and optoelectronic properties of ferrocene and some derivatives (Fe CX, X = H, F) have been investigated by density functional theory. The full potential linearized augmented plane wave including generalized gradient approximation was used in this study. Since the ferrocene family has appealing photochemical and electrochemical properties, they have been extensively used in electronic and photonic industries. The current study accomplishes the electron density, density of states, and optical calculations. We have found that the optoelectronic properties of ferrocene change under substitution of hydrogen with fluorine. Band gaps of 2.72 and 0.92 eV were obtained for FeCH and FeCF, respectively. The band gap was obviously reduced for the full fluorine-substituted ferrocene compared with the unsubstituted one, which exhibited an increase in the charge transfer properties. Results of the optical calculations also confirm these findings. [ABSTRACT FROM AUTHOR]