Fluorine Atom In Position Research Articles

Structure–Properties Correlations in the Range of Cationic Spiropyrans as Analogues of Cyanine Dyes

AbstractRecently the need for smart materials has been extremely growing, and the development of materials with appropriate characteristics has become one of the main challenges. Heptamethine cyanine dyes are widely used in theranostics and photovoltaics due to their remarkable optical properties. However, they are characterized by “rigid” non–changable properties. The main aim of the current study is to unveil correlation between structure and optical properties in the range of vinyl‐3H‐indolium substituted spiropyrans, which can be considered as the closest analogs of heptamethine cyanines with the photocontrolable optical and fluorescent properties. The effects of substitution in indoline and 2H‐chromene cycles, as well as anion change are under the study. To achieve this goal, a series of spiropyran iodides and perchlorates with methyl, methoxy substituents or fluorine atom in position 6′, as well as a conjugated vinyl‐3H‐indolium fragment in position 8′, were synthesized. The structure of the compounds was carefully studied using SC XRD, NMR, IR and mass spectroscopy. Then, studies on absorption and photoluminescence characteristics, as well as photochromic behavior were carried out.

Investigating the Effects of Fluorine Substituents on Organic Dyes in Dye-Sensitized Solar Cells

We synthesized and evaluated five organic dyes that featured both mono- and di-substituted fluorine atoms for application in dye-sensitized solar cells (DSSCs). The dye structure was designed with N, N-dimethylaniline as a donor, fluorophenyl as an π-conjugated bridge, and cyanoacetic acid as an anchoring and acceptor group. The fluorine substituents are strong electron-withdrawing groups, introducing different numbers and positions of fluorine atoms (ortho and meta) that were expected to the ability of the acceptor parts of the dye. The results showed that adding the fluorine mono-substitution in the ortho position can enhance the efficiency of the solar cells in comparison with the meta-substitution and unsubstituted one. However, the di-substitution by fluorine atoms in two ortho positions and ortho, meta positions reduced the performance of the solar cells. The reason was related to the effect of π-conjugation between the fluorine substituent and the carbonyl group of the carboxylic acid. The DSSCs based on dye 14 achieved the best results with power conversion efficiency (PCE) = 3.33%, (Jsc = 5.43 mA cm-2, Voc = 0.81V and FF = 75.85%) under standard conditions with I3-/I- as the electrolyte.

Electrochemical Properties of Derivatives of 1,3-Diphenylisobenzofuran – Chromophores for Singlet Fission

Nowadays, there are efforts to apply alternative sources of renewable energy. One of these sources is solar energy. Solar energy represents a renewable free source of energy that is sustainable and totally inexhaustible. The standard efficiency of solar cells is now below 30 %. Singlet fission has attracted rising attention because it promises to increase the maximum of theoretical efficiency of single-junction solar cells. While solar cells after absorption one photon generates one electron, singlet fission is a photophysical process, whereby a singlet exciton generated by irradiation splits into two triplet excitons [1,2]. In this way, one photon can generate theoretically two electrons which should increase the efficiency of inexpensive single-junction solar cells. Therefore, recently substantial attention has been paid to search for suitable chromophores for singlet fission.When looking for new chromophores for efficient SF, their crystalline form and molecular packing, the relative energies of the S0 (ground state), T1 (lowest triplet), and S1 (first excited singlet) states, where energy of the triplet state should be lower than a half of the first excited singlet energy, and the potentials of one-electron reduction and one-electron oxidation are crucial. Redox properties of molecules for SF are thus critical for their use, therefore electrochemical approach is necessary.Molecules on the base of 1,3-diphenylisobenzofuran (DPIBF) attract an interest because of their possible efficiency for singlet fission. In the last few years we have started to investigate various types of derivatives of DPIBF. One of our first studies [3] was focused on a series of fluorinated derivatives of DPIBF where the influence of number and position of fluorine atoms in the molecule on the redox potentials and mechanism is followed. Next to that we studied series of dimer derivatives of DPIBF [4]. The location and the nature of the bridging unit between two DPIBF redox centres attracted our attention because in this way the shape of the molecule, its extent of electron delocalization and, thus, possible ability of formation of biradicaloid can be changed.The most interesting dimeric molecule appeared to be that one with the elongated π-conjugated system, the “quasi dimer” of DPIBF (2). Because of that, quasi dimer was investigated in more details in comparison with other three molecules by standard electrochemical techniques, the in-situ UV-vis and EPR spectroelectrochemical techniques. The three other derivatives for comparison were parent diphenylisobenzofuran (1), direct dimer (3) and methylene bridged dimer (4). The main goal of this deeper study was to characterize properly not only electrochemical properties of the molecules, but also their absorbance and fluorescence properties and stability in solvents. Acknowledgement This work was supported by the grant 21-23261S (Grant Agency of the Czech Republic) and by the institutional support RVO: 61388955.

Gas-permeable fluorine-substituted poly(diphenylacetylene)s: Effect of number and position of fluorine atoms on gas permeability

Poly(diphenylacetylene)s are ideal for fabricating gas-permeable membranes in gas separation systems. We previously reported the superior gas permeability of fluorine-substituted poly(diphenylacetylene)s compared to their fluorine-free counterparts. In this study, novel poly(diphenylacetylene)s were synthesized by varying the number of fluorine atoms from three to five in the repeating unit (2a, 2b, and 2c). Comparing the gas permeability for 2a–c, the highest value was achieved for poly(diphenylacetylene) with three fluorine atoms in a repeating unit (2a). The oxygen permeability coefficient was 8,100 barrers for 2a, remarkably higher than that of the previously reported poly(diphenylacetylene) with two fluorine atoms in the repeating unit. The density and X-ray diffraction analyses revealed a decrease in the free volume of the membranes with an increase in the number of fluorine atoms. Additionally, 2a–c did not show desilylation because the trimethyl silyl groups were substituted on the benzene ring possessing an electron-withdrawing fluorine atom.

Side Chain Dipole Orientation and Its Effect on Microphase Separation: Experiment and Simulation via Structural Isomer Variation

We use experiments and molecular dynamics simulations in an investigation of structural isomer–property relationships in block copolymers (BCPs) that allow us to isolate the effects of dipole orientation on microphase separation and χ. We combine anionic polymerization of a single parent BCP with post-polymerization thiol-epoxy “click” chemistry with a series of structural isomers of fluorinated thiophenols to synthesize structural isomeric BCPs (SI-BCPs). The resulting SI-BCPs possess identical molecular weight and dispersity, such that only the isomerism can affect microphase separation. Domain periodicity of the SI-BCPs is measured with small angle X-ray scattering, from which χ is estimated. The value of χ for each SI-BCP shows a significant dependence on the position of fluorine atoms on the phenyl ring of the thiophenol. Simulation results show a strong correlation between the dipole moment orientation of the appended thiol and χ, which is also observed in simulations of a BCP of the structural isomers poly(2-vinylpyridine) and poly(4-vinylpyridine). This work illustrates a little-known facet of the structure–property relationship of BCP materials and provides another tool for the molecular engineering of BCPs.

Natural Product-Based Drugs Discovery: Semisynthesis and Biological Evaluation of Ester Derivatives from Pregn-5-ene-3β,17α,20(S)-triol.

There is no doubt that derivation of intermediates from natural product is a very efficient way to develop new environmentally friendly pesticide. We synthesis a succession of compounds esterified with pregn-5-ene-3β,17α,20(S)-triol to evaluate its insecticidal and bacteriostatic activity. Otherwise, their structure-activity relationships (SAR) are also discussed. As a result, compounds 7g, 7h, 7j, 7l and 7o exhibit more obvious insecticidal activity against 3rd Mythimna separata Walker (LC50 = 0.60, 0.68, 0.79, 0.85 and 0.78 mg/mL, respectively) than periplocoside F (PSF). Meanwhile, compounds 7g, 7h and 7i perform well inhibitory activity against Pseudomas syringae pv. actinidiae (Psa) in vitro (minimum inhibitory concentration (MIC) values: 0.10-0.25 mg/mL, minimum bactericidal concentration (MBC) values: 0.15-0.35 mg/mL). And SAR analysis indicates that the replacement and position of fluorine atom on benzoyl are highly vital to biological activity.

Reducing the Permittivity of Polyimides for Better Use in Communication Devices

Recent studies have shown that introducing fluorinated groups into polyimide (PI) molecules can effectively reduce the dielectric constant (Dk) and dielectric loss (Df) of PIs. In this paper, 2,2'-bis[4-(4-aminophenoxy) phenyl]-1,1',1',1',3,3',3'-hexafluoropropane (HFBAPP), 2,2'-bis(trifluoromethyl)-4,4'-diaminobenzene (TFMB), diaminobenzene ether (ODA), 1,2,4,5-Benzenetetracarboxylic anhydride (PMDA), 3,3',4,4'-diphenyltetracarboxylic anhydride (s-BPDA) and 3,3',4,4'-diphenylketontetracarboxylic anhydride (BTDA) were selected for mixed polymerization to find the relationship between the structure of PIs and dielectric properties. Firstly, different structures of fluorinated PIs were determined, and were put into simulation calculation to learn how structure factors such as fluorine content, the position of fluorine atom and the molecular structure of diamine monomer affect the dielectric properties. Secondly, experiments were carried out to characterize the properties of PI films. The observed change trends of performance were found to be consistent with the simulation results, and the possible basis of the interpretation of other performance was made from the molecular structure. Finally, the formulas with the best comprehensive performance were obtained respectively. Among them, the best dielectric properties were 14.3%TFMB/85.7%ODA//PMDA with dielectric constant of 2.12 and dielectric loss of 0.00698.

Influence of fluorine substitution position on electrochromic and capacitive properties of hybrid conjugated polymer

Fluorine atom as side chain substituted conjugated polymer exhibits enhanced photoelectric performance due to the intra- and inter-molecular interaction. However, the strong molecular aggregation due to the existence of fluorine atom inhibits the doping ion transport in conjugated polymer. Here, two fluorine substituted hybrid conjugated polymers, poly(BisTh-o-2F) and poly(BisTh-p-2F), based on para-phenylene and thiophene were prepared by electrochemical method. The molecular structure difference of the two hybrid conjugated polymers is the substitution position of fluorine atom. The two hybrid conjugated polymers exhibit similar redox property and optical absorption region. During oxidation process, the colors of the two hybrid conjugated polymers turn from dark red to blue. Kinetic studies demonstrate that fluorine atom ortho-substituted poly(BisTh-o-2F) possesses faster response time than that para-substituted poly(BisTh-p-2F) due to the decreased molecular aggregation. However, poly(BisTh-p-2F) exhibits higher optical contrast than poly(BisTh-o-2F) under different wavelengths. The charge-discharge experiments demonstrate that poly(BisTh-o-2F) possesses much higher specific capacitance than poly(BisTh-p-2F). And, the energy storage states of the two conjugated polymers could be monitored by the color variation, demonstrating they possess great application potential in electrochromic supercapacitor.

Fluorine Atoms on C6H5-Corrole Affect the Interaction with Mpro and PLpro Proteases of SARS-CoV-2: Molecular Docking and 2D-QSAR Approaches.

The chymotrypsin-like cysteine protease (3CLpro, also known as main protease—Mpro) and papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been used as the main targets for screening potential synthetic inhibitors for posterior in vitro evaluation of the most promising compounds. In this sense, the present work reports for the first time the evaluation of the interaction between Mpro/PLpro with a series of 17 porphyrin analogues-corrole (C1), meso-aryl-corrole (C2), and 15 fluorinated-meso-aryl-corrole derivatives (C3–C17) via molecular docking calculations. The impact of fluorine atoms on meso-aryl-corrole structure was also evaluated in terms of binding affinity and physical-chemical properties by two-dimensional quantitative structure–activity relationship (2D-QSAR). The presence of phenyl moieties increased the binding capacity of corrole for both proteases and depending on the position of fluorine atoms might impact positively or negatively the binding capacity. For Mpro the para-fluorine atoms might decrease drastically the binding capacity, while for PLpro there was a certain increase in the binding affinity of fluorinated-corroles with the increase of fluorine atoms into meso-aryl-corrole structure mainly from tri-fluorinated insertions. The 2D-QSAR models indicated two separated regions of higher and lower affinity for Mpro:C1–C17 based on dual electronic parameters (σI and σR), as well as one model was obtained with a correlation between the docking score value of Mpro:C2–C17 and the corresponding 13C nuclear magnetic resonance (NMR) chemical shifts of the sp2 carbon atoms (δC-1 and δC-2) of C2–C17. Overall, the fluorinated-meso-aryl-corrole derivatives showed favorable in silico parameters as potential synthetic compounds for future in vitro assays on the inhibition of SARS-CoV-2 replication.

Spectral, structural, and pharmacological studies of perillaldehyde and myrtenal based benzohydrazides

N-Acylhydrazones have been an interesting scaffold due to their diverse biological activities toward different therapeutic targets. We synthesized seven new N'‐[(E)‐[(4S)‐4‐(prop‐1‐en‐2‐yl)cyclohex‐1‐en‐1‐yl]methylidene]benzohydrazides as well as seven new N'-[(E)-{6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl}methylidene]benzohydrazides. The structure of synthesized hydrazides has been studied by using X-ray analysis, FT-IR, NMR, and HRMS spectra. Derivatives containing fluorine atoms in position 2 of the phenyl ring display versatile structures in solution and the solid state. The 1H NMR spectra of 3c and 5c measured in DMSO-d6 display at ambient temperature two unequally populated sets of signals. These facts confirm the existence of the two conformers of 3c and 5c of different stability which interconvert by rotation about their C―N bond slowly enough to lead to discrete sets of signals in 1H NMR spectra at room temperature. The kinetics of the conformational interconversion of derivatives 3c and 5c in DMSO-d6 were studied by two-dimensional exchange spectroscopy (2D EXSY). In 1H NMR spectra of 3c and 5c measured in CDCl3 and acetone-d6 was observed the strong splitting of the H-2 signal into a doublet because of H-bond formation between organic fluorine and NH donor. The FT–IR spectra of 3a–g and 5a–g confirmed the presence of the H-bonds N–H···O=C and N–H···N. Hydrazones 3f, 5a, and 5c crystallize in the P1 space group and the asymmetric units contain two pairs of pseudo-centrosymmetric molecules. Hydrazone 5b crystallizes in the P41 space group and the asymmetric units contain only one molecule. In the crystal, the molecules in 3f, 5a and 5b are linked through N―H···O hydrogen bonds, in 5c also N―H···N hydrogen bonds are present. In contrast to the NMR, the X-ray and IR spectra did not give unambiguous evidence of the F···H−N H-bond. The synthesized hydrazones 3c and 3g exhibited excellent antiproliferative effects in Jurkat cells with IC50 values of 3.8 and 4.2 μM, respectively. Our findings indicate that these compounds are promising antitumor agents.

Induction of the smectic A phase in liquid crystalline mixtures formulated using non-chiral compounds with positive and negative dielectric anisotropy

ABSTRACT The induction of the SmA phase in mixtures of non-chiral nematic compounds with the positive and the negative dielectric anisotropy is presented which is obtained by different substitutions of fluorine atoms. One component is a three-ring tolane with polar group – OCF3 in position 4 and two fluorine atoms in positions 3 and 5 in the terminal phenyl ring. The other component is two ring tolane with two or four fluorine atoms in the lateral position. Based on phase diagrams, the influence of the alkyl chain length of both types of compounds on the induction phenomenon is shown. Results of the X-ray measurements confirm that the induced phase is a monolayer SmA phase. The increase of the alkyl chain length causes the increase in the strength of the induction in mixtures, i.e. the induced SmA phase is observed for a wider range of the temperature and concentration of mixture components.

Optical and static dielectric properties of two nematogenic isothiocyanato-tolane compounds: a comparative study

The optical and dielectric properties of two laterally monofluorinated isothiocyanato-tolane nematogens, which differ only on the position of fluorine atom in the core, have been studied as a function of temperature. A four-parameter model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the compounds with the theoretical ones. The position of fluorine substituent in the rigid core have been found to have little effect on optical birefringence, but pronounced effect on dielectric anisotropy.

Synthesis of New Valinol‐Derived Sultam Triazoles as α‐Glucosidase Inhibitors

Abstractα‐Glucosidase inhibition is one of the key targets for controlling diabetes. In consideration of that, new L‐valinol derived fluorinated sultam triazoles were synthesized as α‐glucosidase inhibitors, and their activities were further compared with the precursor molecules (sulfonamides, sultams, and N‐propargyl sultams). Primarily, all the synthesized sultam triazoles and precursor compounds (sulfonamides, sultams, and N‐propargyl sultams) were evaluated for different biological activities, including cytotoxicity, anti‐inflammatory, and α‐glucosidase inhibitory activities. Results revealed that only sultam triazoles exhibited inhibition against α‐glucosidase enzyme (IC50 values: 173 to 194 μM) using acarbose (IC50: 875.85 ± 2.03 μM) as the standard drug. These sultam triazoles were prepared after few steps, starting from enantiopure L‐valinol, which differ electronically (due to the position of fluorine atom and different positions on aromatic ring). Structures of all the compounds were evaluated using different spectroscopic techniques. Kinetics of active compounds were also investigated to find their mode of inhibition.

The Role of Fluorine-Substituted Positions on the Phase Transition in Organic-Inorganic Hybrid Perovskite Compounds.

Although research on organic-inorganic hybrid perovskites (OIHPs) has grown exponentially in the past two decades, the high phase transition temperature of OIHP materials is still one of the insurmountable difficulties. Herein, a series of A2BX4 type OIHP materials [(2,n-DFBA)2PbCl4] (n = 3, for 1; n = 4, for 2; n = 5, for 3; n = 6, for 4) have been prepared by reactions of double-substituted difluorobenzylamine (difluorobenzylamine = DFBA) with lead chloride in concentrated HCl aqueous solution. It was found the OIHP compounds 1-3 proceed a switchable phase transition with phase transition temperatures (Tc) at 449 K (1), 462 K (2) and 500 K (3), higher than that of the parent compound [(BA)2PbCl4] (BA = benzylammonium) at 438 K, but compound 4 exhibits no phase transition. A crystal structure analysis elucidated that the organic template ligands DFBA lead in the inorganic part in compounds 1-3 to a two-dimensional (2D) perovskite structure, while that in compound 4 leads to a one-dimensional (1D) chain structure. The different double-substituted positions of fluorine atoms on benzylamine have important influences on the phase transition in compounds 1-4.

(Invited) Electrochemistry for Singlet Fission

Very recently, substantial attention has been paid to search for suitable chromophores for singlet fission. Singlet fission (SF) is a photophysical process in which an organic chromophore in excited singlet state shares its excitation energy with a neighbouring ground-state chromophore and both are converted into two triplet states. [1,2] In this way, one photon can generate theoretically two electrons which should increase the efficiency of inexpensive single-junction solar cells. This spin-allowed process is very fast (in ps or fs time scale), therefore much slower radiative decay is out of competition. Nevertheless, its detailed mechanism is still unknown. Although up to now, SF has not found its way into practice, the synthetic, photophysical, electrochemical and computational research is running.When looking for new molecules – candidates for efficient SF, the following properties are crucial: their crystalline form and molecular packing, the relative energies of the S0 (ground state), T1 (lowest triplet), and S1 (first excited singlet) states, where energy of the triplet state should be lower than a half of the first excited singlet energy, and the potentials of one-electron reduction and one-electron oxidation. Redox properties of molecules for SF are thus critical for their use, therefore electrochemical approach is necessary.Nowadays two main promising groups of chromophores are investigated for SF: 1) functionalized polyacenes, mostly pentacenes, and 2) organic molecules which are able to form biradicaloids, on which our research is aimed.Derivatives of 1,3-diphenyl-isobenzofuran derivatives (DPIBF) were chosen as a first group of molecules suitable for SF. Our study was focused on a series of fluorinated derivatives of DPIBF where the influence of number and position of fluorine atoms in the molecule on the redox potentials and mechanism is followed. With increasing number of F atoms, two discontinuous changes of behavior (mechanisms) were found [3].The second family of molecules which are currently under our investigation are derivatives of a very stable dye cibalackrot which are based on indigo structure. Our current work is focused on the study of oxidation and reduction of a series of differently substituted compounds.In all cases, electrochemical investigation was performed using classic voltammetric techniques (polarography, CV and RDE) and their combination with in situ UV-vis and EPR spectroscopy. The experimental results are correlated with quantum chemical calculations. Acknowledgement The financial support of the grant 19-22806S (Czech Science Foundation - GAČR) and the institutional support RVO: 61388955 are highly appreciated. The authors are grateful to dr. J. Kaleta and dr. M. Dudic for granting the substances and to prof. J. Michl for valuable discussions.

Exploring influence of fluorine substitution on the strength and nature of halogen bond between iodobenzene and hydrogen cyanide

AbstractIn the present study, the intermolecular I … N halogen bond (XB) interaction between iodobenzene (IBZ) and its fluorinated derivatives (as Lewis acids LA 1 through LA 20) with HCN (as Lewis base LB) is theoretically explored to shed light on the electronic nature and strength of the mentioned non‐covalent interaction (NCI). The hydrogen atoms of phenyl ring in IBZ were substituted by fluorine atom to probe different impacts of this atom. Such a substitution is paid attention from the number as well as the position of fluorine atoms points of view. Our analyses reveal that this XB interaction whose interaction energy spans a narrow range between 1.0 and 3.0 kcal·mol−1should be classified as a weak NCI. The symmetry‐adapted perturbation theory (SAPT) analysis evidences that the I … N XB in the investigated binary complexes (BCs) is mainly dominated by electrostatic and dispersion interactions, and, in the meantime, induction interactions can safely be ignored. Among the many I … N XB descriptors,Vs,max, which corresponds to the most positive value of electrostatic potential computed for the iodine atom in LAs, plays a key role. Indeed, such an easily and rapidly computable quantity (Vs,max) allows a sufficiently accurate prediction of interaction energy together with SAPT‐derived components analysis to become feasible by a simple inclusion ofVs,maxvalue within the numerous explored estimators. Although the strength of I … N XB interaction in the studied BCs is increased by an increase in the number of fluorine substituent, the position of fluorine atom cannot significantly alter the strength of the mentioned interaction.

The influence of fluorinated position on the performance of isoindigo-based polymer solar cells

Two novel donor-acceptor (D-A) polymers based on two-dimensional conjugated alkylthienyl substituted benzo[1,2-b:4,5-b′]dithiophene and difluorine substituted isoindigo derivatives were synthesized with the structures as poly{6-(4,8-bis(4,5-dioctylthiophen-2-yl)-benzo[1,2-b:4,5-b′]-dithiophen-2-yl)−5,5′-difluoro-1,1′-dioctyl-isoindigo} (P1) and poly{5-(4,8-bis(4,5-dioctyl-thiophen-2-yl)-benzo[1,2-b:4,5-b′]-di-thiophen-2-yl)−4,6-difluoro-1,1′-dioctyl-isoindigo} (P2), respectively. Thermal stability, absorption properties, energy levels and photovoltaic properties of the polymers were intensively investigated. The symmetric polymer P1 showed broad absorption in comparison with the asymmetric polymer P2 both in solution and solid film, corresponding to their band gaps of 1.45 (P1) and 1.59 (P2) eV, respectively. The copolymers possessed similar high-lying highest occupied molecular orbital (HOMO) levels of – 5.34 (P1) and – 5.32 eV (P2). The performance of conventional solar cells based on copolymers/PCBM (PC61BM and PC71BM) films were investigated. All of P2-based PSCs delivered superior power conversion efficiencies (PCEs) and higher short circuit current (Jsc) than P1-based devices, where a best PCE up to 4.23% was obtained from P2/PC71BM device by THF solvent-vapor-annealing (SVA) treatment with an open-circuit voltage (Voc) of 0.88 V, a Jsc of 8.27 mA/cm2 and a fill factor (FF) of 0.578. The encouraging performance was attributed to its good miscibility, preferable nanophase separation and high mobilities, as well as efficient exciton dissociation with weak bimolecular and trap recombination. In this study, the incorporated position of fluorine atoms on IID-based copolymer influences not only the thin-film structure such as phase separation structure but also photophysical/electrochemical properties and photovoltaic performance, which highlights a new strategy for the design and synthesis of fluorinated D-A polymers.

Synthesis of fluorinated 3-hydrazino-1,2,4-triazino[5,6-b] indoles as novel herbicidal systems

A few fluorinated 3-hydrazino-1,2,4-triazino[5,6-b] indoles ( 5 - 8 ) have been synthesized and screened for their herbicidal effect. Treatment of 3-hydrazino-8H/8-fluoro-1,2,4-triazino[5,6-b] indoles ( 3 and 4 ) with fluorinated acyl derivatives ( A and B ) yielded the rich fluorine 1,2,4-triazino indole. Structure of the products have been established by elemental analysis and spectral measurements. The presence and position of fluorine atoms have been deduced from 19 F NMR. The novel fluorinated hydrazino-1,2,4-triazino[5,6-b] indoles have been tested for post-emergent herbicidal activity against grass weed species and broadleaf weed species.

Theoretical Description, Synthesis, and Structural Characterization of β-Na0.33V2O5 and Its Fluorinated Derivative β-Na0.33V2O4.67F0.33: Influence of Oxygen Substitution by Fluorine on the Electrochemical Properties.

The structure of β-Na0.33V2O4.67F0.33 has been investigated by both theoretical and experimental methods. It exhibits the same structure as that of the parent bronze β-Na0.33V2O5. The partial substitution of oxygen by fluorine has little effect on the average structure and cell parameters, but the sodium environment changes significantly. Using DFT calculations, we determined the most stable positions of fluorine atoms in the unit cell. It was found that the partial replacement of oxide by fluoride takes mainly place in the coordination sphere of Na producing a shortening of the Na-anion bond lengths. We also analyzed the electronic properties based on density of states and Bader charge distribution. The crystallochemical situation of sodium ions in β-Na0.33V2O4.67F0.33 oxyfluoride, detected by both experimental and computational methods, affects its mobility with respect to the parent oxide. The higher ionicity in the Na coordination sphere of β-Na0.33V2O4.67F0.33 is related to a sodium ion diffusion coefficient, DNa+, that is 1 order of magnitude lower (1.24 × 10-13 cm2 s-1) than in the case of β-Na0.33V2O5 (1.13 × 10-12 cm2 s-1). Electrochemical sodium insertion/deinsertion properties of the oxyfluoride have been also investigated and are compared to the oxide. Insertion/deinsertion equilibrium potential for the same formal oxidation state of vanadium increases due to fluorination (for instance reduction of V+4.3 occurs at 1.5 V in the oxide and at 1.75 V in the oxyfluoride). However, the capacity of Na0.33V2O4.67F0.33 at constant current is lower than in the case of β-Na0.33V2O5 due to a less adequate morphology, a lower DNa+, and a lower oxidation state of vanadium owing to the aliovalent O/F substitution.

Synthesis, Characterization, and Antibacterial Activity of Cd(II) Complexes with 3-/4-Fluorobenzoates and 3-Hydroxypiridine as Co-Ligands

In this study, two new complexes of Cd(II) 4-fluorobenzoate (4-FB)/3-fluorobenzoate (3-FB) with 3-hydroxypyridine (3-HPY) have been synthesized and structural characterizations have been performed by using elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction methods. In both complexes, the metal atom is chelated by two carboxylate groups from two 4- or 3-fluorobenzoate anions and coordinated by two 3-hydroxypyridine (HPY) molecules. In both complexes, an oxygen atom of carboxylate from the adjacent anion bridges to the Cd atom, completing the distorted seven-coordination geometry. The only difference between complexes is the positions of fluorine atoms in fluorobenzoic acids (4-fluorobenzoic acid (complex 1) and 3-fluorobenzoic acid (complex 2)). Antibacterial resistance of two new complexes to some bacteria has been investigated.