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Here, we analyzed the performance of a hydrogen/bromate fuel cell (HBFC) operating in batch recirculation mode. We adjusted the catholyte composition and operating conditions to ensure stable cell discharging and prevent the formation of liquid bromine. To achieve this, we analyzed the evolution of bromate catholytes with different acid content using thermodynamic calculations, which considered equilibria between bromine compounds and material balance for protons. We used the results of these calculations and data on catholyte chemical stability to select compositions appropriate for HBFC testing. To obtain data on catholyte evolution, we employed novel spectrophotometric and electrochemical in situ/operando techniques. Our study revealed that the composition of the catholyte and its average oxidation state, as well as the interplay between chemical and electrochemical reactions, significantly impact the power output of the HBFC. The main practical finding of our study is that under optimized conditions, the HBFC demonstrated both high energy density and reasonable performance. For instance, with a catholyte composition of 1 M LiBrO 3 and 0.3 M H 2 SO 4 , energy density is 116 Wh L−1 (theoretical 1270 Wh L−1 for 5.5 M LiBrO 3) the cell operated with 98.7% capacity utilization and power of 194 mW cm−2 at 250 mA cm−2. • Operation of H 2 /BrO 3 fuel cell in batch recirculation mode is studied. • Catholyte composition during device discharge measured by in-situ methods. • Main components of acidic bromate catholyte are BrO 3 −, Br 2 , Br−, and Br 3 − • Interplay between chemical and electrochemical reactions determines power output. • CU of H 2 /BrO 3 fuel cell reaches up to 98.7 % at 250 mA cm−2 [ABSTRACT FROM AUTHOR]

In this paper, statistical analysis and experimental methods are employed to study the hydrobromination of hydroxyl-terminated polybutadiene (HTPB) elastomer by 48% hydrobromic acid. The effect of three variables including time, temperature, and volume of acid, on the percentage of hydrobromination is investigated. The influence of these parameters and their interaction is checked through the analysis of variance and sensitivity analysis, and the optimum values for 10% hydrobromination are obtained 24 h, 30 °C, and 5.05 ml of the acid volume. A hydrobrominated resin is synthesized by applying optimal conditions for hydrobromination of 10% of double bonds. The results obtained from classical analysis and NMR show the amount of hydrobromination as 9.89% and 9.38%, respectively. The placement of the bromine atom in the compound is confirmed by ATR and NMR analysis. Also, DSC analysis shows that the glass transition temperature (Tg) of the hydrobrominated product increased by 2.86 °C compared to the initial HTPB. [ABSTRACT FROM AUTHOR]

Bromine activation (the production of Br in an elevated oxidation state) promotes ozone destruction and mercury removal in the global troposphere and commonly occurs in both springtime polar boundary layers, often accompanied by nearly complete ozone destruction. The chemistry and budget of active bromine compounds (e.g., Br2 , BrCl , BrO , HOBr) reflect the cycling of Br and affect its environmental impact. Cyanogen bromide (BrCN) has recently been measured by iodide ion high-resolution time-of-flight mass spectrometry (I- CIMS), and trifluoro methoxide ion time-of-flight mass spectrometry (CF3O- CIMS) during the NASA Atmospheric Tomography Mission second, third, and fourth deployments (NASA ATom), and could be a previously unquantified participant in active Br chemistry. BrCN mixing ratios ranged from below the detection limit (1.5 pptv) up to as high as 36 pptv (10 s average) and enhancements were almost exclusively confined to the polar boundary layers in the Arctic winter and in both polar regions during spring and fall. The coincidence of BrCN with active Br chemistry (often observable BrO , BrCl and O3 loss) and high CHBr3/CH2Br2 ratios imply that much of the observed BrCN is from atmospheric Br chemistry rather than a biogenic source. Likely BrCN formation pathways involve the heterogeneous reactions of active Br (Br2 , HOBr) with reduced nitrogen compounds, for example hydrogen cyanide (HCN / CN-), on snow, ice, or particle surfaces. Competitive reaction calculations of HOBr reactions with Cl- / Br- and HCN / CN- in solution, as well as box model calculations with bromine chemistry, confirm the viability of this formation channel and show a distinct pH dependence, with BrCN formation favored at higher pH values. Gas-phase loss processes of BrCN due to reaction with radical species are likely quite slow and photolysis is known to be relatively slow (BrCN lifetime of ∼ 4 months in midlatitude summer). These features, and the lack of BrCN enhancements above the polar boundary layer, imply that surface reactions must be the major loss processes. The fate of BrCN determines whether BrCN production fuels or terminates bromine activation. BrCN reactions with other halogens (Br- , HOCl , HOBr) may perpetuate the active Br cycle; however, preliminary laboratory experiments showed that BrCN did not react with aqueous bromide ion (< 0.1 %) to reform Br2. Liquid-phase reactions of BrCN are more likely to convert Br to bromide (Br-) or form a C – Br bonded organic species, as these are the known condensed-phase reactions of BrCN and would therefore constitute a loss of atmospheric active Br. Thus, further study of the chemistry of BrCN will be important for diagnosing polar Br cycling. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of the solid solutions of 1D lead-free halide perovskites, (C2H5NH3)2BiCl5−xBrx (x = 0–5), using a solution method. All the synthesized compounds adopt the orthorhombic Cmca space group at room temperature (RT) (293 K) and undergo a phase transition to a low symmetry orthorhombic space group, Aba2, at a low temperature (LT) of 90 K. All the structures contain BiX6 (X = Cl or Br) corner-sharing polyhedra, forming zigzag 1D chains. The symmetry breaking phase transition from Cmca (293 K) to Aba2 (90 K) is due to the ordering of the ethylamine (removal of mirror plane) unit caused by strong H-bond formation in the low-temperature phase (LT phase). The TGA analysis indicates that (EA)2BiCl5 (EA = C2H5NH3+) is less stable than its bromine analogue. Optical studies show that all the compounds are of indirect band gap type with a band gap of 3 eV for the pristine chlorine compound and 2.5 eV for the pristine bromine compound. The band gap value gradually decreases with the incorporation of bromine at the chlorine site, following Vegard's law. According to the dielectric measurement, the pristine chlorine compound (x = 0) has a dielectric constant (εr) of 530, whereas that of the pristine bromine compound (x = 5) is 106 at room temperature and 10 kHz frequency. [ABSTRACT FROM AUTHOR]

The Z-scan instrument was used to study the nonlinear optical (NLO) properties of the derivatives of 3,3′-biindole 2,2′(1H,1′H)-dione, with different substitutions such as bromine, methyl, and phenyl groups. Specifically, the nonlinear absorption coefficient, β, nonlinear refraction index, n 2 , have been extracted and reverse saturation absorption and self-defocusing phenomena were investigated. It is observed that the presence of bromine in the compound structure can reduce the NLO properties. The reduction of dipole moment with bromine substitutions in the compound structure was confirmed with the quantum calculation. The NLO properties of the biindole derivatives related to the thermo-optic coefficient and dipole moment of the compound. Overall, our findings indicate that the biindole derivatives are promising candidates for NLO absorption materials. [ABSTRACT FROM AUTHOR]

A series of new ethyl 7-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylates and their halogenated derivatives were synthesized. Ethyl 7-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylate (2) was obtained by the condensation of 2-amino-4-hydroxybenzaldehyde and diethyl malonate. Halogenation of compound 2 with bromine led to the formation of 6,8-dibromo derivative 5, and the acylation and alkylation of 2 and 5 with acetic anhydride and p-chlorophenacyl bromide gave the corresponding acetoxy derivatives 3 and 6 and alkoxy derivatives 4 and 7. Compounds 2–7 were evaluated for their in vitro antiproliferative activity against MCF-7 and HepG2 cancer cell lines. The cell cycle analysis of compound 4 demonstrated cell cycle arrest at the G2/M phase and pre-G1 apoptosis. [ABSTRACT FROM AUTHOR]

The presence of reactive bromine in polar regions is a widespread phenomenon that plays an important role in the photochemistry of the Arctic and Antarctic lower troposphere, including the destruction of ozone, the disturbance of radical cycles, and the oxidation of gaseous elemental mercury. The chemical mechanisms leading to the heterogeneous release of gaseous bromine compounds from saline surfaces are in principle well understood. There are, however, substantial uncertainties about the contribution of different potential sources to the release of reactive bromine, such as sea ice, brine, aerosols, and the snow surface, as well as about the seasonal and diurnal variation and the vertical distribution of reactive bromine. Here we use continuous long-term measurements of the vertical distribution of bromine monoxide (BrO) and aerosols at the two Antarctic sites Neumayer (NM) and Arrival Heights (AH), covering the periods of 2003–2021 and 2012–2021, respectively, to investigate how chemical and physical parameters affect the abundance of BrO. We find the strongest correlation between BrO and aerosol extinction (R=0.56 for NM and R=0.28 for AH during spring), suggesting that the heterogeneous release of Br2 from saline airborne particles (blowing snow and aerosols) is a dominant source for reactive bromine. Positive correlations between BrO and contact time of air masses, both with sea ice and the Antarctic ice sheet, suggest that reactive bromine is not only emitted by the sea ice surface but by the snowpack on the ice shelf and in the coastal regions of Antarctica. In addition, the open ocean appears to represent a source for reactive bromine during late summer and autumn when the sea ice extent is at its minimum. A source–receptor analysis based on back trajectories and sea ice maps shows that main source regions for BrO at NM are the Weddell Sea and the Filchner–Ronne Ice Shelf, as well as coastal polynyas where sea ice is newly formed. A strong morning peak in BrO frequently occurring during summer and that is particularly strong during autumn suggests a night-time build-up of Br2 by heterogeneous reaction of ozone on the saline snowpack in the vicinity of the measurement sites. We furthermore show that BrO can be sustained for at least 3 d while travelling across the Antarctic continent in the absence of any saline surfaces that could serve as a source for reactive bromine. [ABSTRACT FROM AUTHOR]

This work presents macroscopic fibers of aligned double-walled carbon nanotubes (DWCNTs) intercalated with long-range ordered bromine, with a stoichiometry close to C 17 Br. Tribromide ions lie inside interstitial sites between hexagonally-packed DWCNTs and extend parallel to their axis as ordered supramolecular "wires". First-principles simulations confirm this structure and a transfer of 0.13 electrons per Br atom. The structure of nested bundles of CNTs with a homogeneous distribution of bromine species in the interstitial sites of the superlattice is directly imaged by cross-sectional HRTEM, showing full intercalation of highly dense and aligned fibers. The presence of Br 2 and B r 3 – is confirmed by Raman spectroscopy, and their supramolecular organization is resolved by 2D wide-angle X-ray scattering. Intercalation increases room-temperature longitudinal electrical conductivity by a factor of 8.4. Through low-temperature transport measurements in the longitudinal and transverse directions, we show that the intercalate reduces the tunneling-dominated resistance associated with transport between adjacent CNTs, rather than exclusively acting as a dopant that increases conductance of individual CNTs. By preserving the separation between CNTs, the exceptional mechanical properties of the CNT fiber host are retained. The combined tensile strength above 2.46 GPa and conductivity of 10.68 MS/m makes intercalated CNT fibers attractive lightweight conductors with combined properties superior to metals and graphite intercalation compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Different bromine compounds have found numerous applications. Nevertheless, there is still insufficient information about environmental chemistry of this trace element. In our research, a greenhouse pot experiment was carried out with the following aims: (1) to study the response of wheat and pea seedlings to an increase of concentrations two bromides (KBr and NaBr) in soil, (2) to assess the influence of root exudates of the two plant species on uptake of Br and some other macro- and trace elements when wheat and pea grow close to each other or far apart, and (3) to estimate possible allelopathic effects on the uptake of different elements by plants and also on the concentrations of polycyclic aromatic hydrocarbons in uncontaminated soil and in the soil contaminated by bromides. Both plant species were capable of accumulating large amounts of bromine. The concentration of bromine in roots of pea was higher than in wheat roots, and was always higher in leaves of wheat than in leaves of pea. More bromine was accumulated in roots of wheat and pea seedlings growing separately than in roots of the seedlings grown close to each other. Growth of wheat and pea seedlings in uncontaminated and spiked with bromides soils resulted in decrease of the concentrations of some polycyclic aromatic hydrocarbons in the rhizosphere soil of the plants. The variations depended on the plant species and were different when the plants were grown close to each other and separately. [ABSTRACT FROM AUTHOR]

Hypervalent compounds play a prominent role in homogeneous oxidation catalysis. Despite the higher reactivity of hypervalent bromine compounds when compared to their isoelectronic iodine analogues, the corresponding λ3-bromanes are much less explored. This can be attributed to the discernible lack of convenient strategies for their synthesis. This short review highlights the available methods for the synthesis of various organo-λ3-bromanes, with a major focus on the recent developments and reactivities in the last few years. Additionally, limitations and future prospects of hypervalent bromine chemistry are discussed. 1 Introduction 2 Diaryl-λ3-bromanes 3 Dialkyl-λ3-bromanes 4 Dihetero-λ3-bromanes 5 Alkenyl-λ3-bromanes 6 Alkynyl-λ3-bromanes 7 Conclusion and Prospects [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • Synthesis of m -terphenyls functionalized with amino, diethylamino, piperidine and pyrrolidine moieties. • One-component free-radical photoinitiators based on m -terphenyl core. • Two-component photoinitiating systems for free radical and cationic photopolymerization. • Visible light photoinitiating systems. • Performence of terphenyl-based photoinitiating systems in 3D printing. A series of eight m -terphenyl-based compounds functionalized with amino, diethylamino, piperidine, and pyrrolidine moieties were synthesized and investigated for the first time as one-component free-radical photoinitiators for acrylate and methacrylate monomers. Developed compounds were also applied as photosensitizers of iodonium salt in two-component initiating systems for free radical and cationic photopolymerization. That is why they are excellent for hybrid polymerization e.g. synthesis of interpenetrating polymer networks (IPN). The mechanical properties of produced IPN samples were measured. We investigated the effect of the amine group modification and the presence of one or two bromine atoms on the photophysical and electrochemical properties of the m -terphenyls and their consequent efficiency in polymerization processes. Two bromine substituents in the molecule slightly shift the absorption spectrum towards longer wavelengths in comparison to a compound with one bromine atom. Functionalization of amine group by the introduction of alkyl moieties strongly affects absorption properties, the wavelength corresponding with the maximum absorption values increases in the following order: amine group > diethylamine group > piperidine group > pyrrolidine group. Investigated compounds were found to be efficient in photoinitiating systems for free-radical, cationic, and hybrid photopolymerization, kinetic of polymerization processes with the use of different monomers were followed using real-time FT IR methodology. Moreover, the chemical mechanism was investigated using photolysis and ESR experiments. Developed photoinitiators were also applied for laser writing experiments. In the next step, the key printing parameters were settled, the critical energy necessary to initiate polymerization (E c) and penetration depth of curing light (D p), and studied systems were applied for resin used for LCD-based 3d printing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Complete removal of bromine signifies the ultimate aim of the chemical recycling of e-waste. • This work investigates fixation of bromine from pyrolysis of TBBA by Ca(OH) 2. • A multitude of experimental measurements illustrate a 100% debromination capacity of Ca(OH) 2. • The condensate oil fraction is dominated by n -alkanes. • A reaction mechanism based on DFT calculations elucidate the HBr fixation route. Complete and deep removal of bromine from polymeric constituents in waste printed circuit boards (WPCBs) signifies the prime aim of the commonly deployed catalytic/pyrolytic approach in the treatment of e-waste. To attain this aim, a wide array of debromination agents were utilized with varying degree of effectiveness, scalability, and economic viability. Through the use of a multitude of techniques (flow reactor experiments, chemical analysis, surface characterization, and molecular simulation), this work presents conclusive evidence that co-pyrolysis of tetrabromobisphenol A (TBBA; as a model compound for the bromine content in WPCBs) with calcium hydroxide (Ca(OH) 2) results in a complete fixation of the bromine content and produces bromine-free pyrolysis oil. For instance, measurements by IC and FTIR (gas sampling cell) confirms the disappearance of HBr from the gaseous stream during co-pyrolysis of a TBBA (1):Ca(OH) 2 (2) mixture between 200 and 500 °C. Likewise, no brominated compounds could be detected from the analysis of the condensate and gas fractions. As the collected oil is dominated by n -alkanes, it is concluded that Ca(OH) 2 displays both cracking and debromination capacity. DFT calculations maps out reaction pathways for the transformation of Ca(OH) 2 into CaBr 2 via the dissociative addition of HBr molecules. Formed CaBr 2 could open a venue for a complete recovery of bromine in the thermal treatment of e-waste. Outcomes reported herein shall be instrumental in the design and operation of an effective chemical recycling facility for the ever-increasing loads of e-waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first bent-core mesogens with the azocinammoyl scaffold in the side wings are described. • Introduction of substituents into the central and outer rings reveals rich mesomorphism. • The NO 2 group in the obtuse angle of the bent core leads to a B 7 phase. • Some of the compounds exhibit LC phases typical for rod-like molecules. A series of bent-core liquid crystals possessing the azocinnamoyl unit in both elongating side arms was synthesized. The chain length was kept fixed for each molecule (C 12 H 25), whereas the substituents at the central and outer rings were varied. The LC phases were assigned by polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction. The investigated compounds are suitably diverse to reveal some aspects of the relationship between molecular structure and the mesomorphic properties. Namely, non-substituted parent compound is crystalline only and the methyl group in position 2 or the chlorine atom in position 4 of the central ring suppresses LC phase formation. Introduction of the strong electron-withdrawing nitro group between the side arms on the central ring leads to a B 7 phase. Compounds possessing a bromine atom or two chlorine atoms in the neighbourhood of the ester groups form LC phases typical for rod-like molecules, namely a nematic – smectic phase sequence. The results are compared with those reported for the azobenzoyl analogues. [ABSTRACT FROM AUTHOR]

[Display omitted] • The partial substitution of bromine by chlorine allowed to obtain a one-dimensional material while the pure chlorine and bomine compounds are supramolecular and modified the role of the organic part which passes from a counter ion in pure bromine or chlorine compounds to a chelating bidentate ligand in the mixed complex. • The thermogravimetric analysis indicates that the precursor decomposes in two stages giving rise to the copper oxide CuO as final residue. • The new compound is characterized by band gap energy of 2.92 eV so it can be classified as semiconductor material which is of preeminent importance for the optoelectronics applications. A new organic–inorganic copper-based hybrid material containing ethylendiamine as organic part and mixed bromide/chloride as halide ions has been synthesized and crystallographically characterized. At room temperature, this new compound adopts the monoclinic symmetry (space group P 2 1 / m) and presents the following unit-cell parameters: a = 6.927(3) Å, b = 5.884(3) Å, c = 8.399(4) Å, β = 94.856(13)°, V = 341.1(2)Å3 and Z = 2. The 1D structure of the title compound consists of infinite dimeric chains running along the crystallographic b axis. These chains are constructed from dimeric units [Cu 2 Br 2 Cl 2 (C 2 H 8 N 2) 2 ] linked together by sharing (Br/Cl) atoms. N-H...Br/Cl hydrogen bonds guarantee the connection between the dimeric chains and the cohesion of the structure. The thermogravimetric analysis shows that this new hybrid material decomposes in two stages giving rise to the copper oxide as final residue. The UV–visible absorption shows that the new complex undergoes three optical absorption bands at 238, 317 and 686 nm, respectively. From the gap energy value of 2.92 eV it can be concluded that the new mixed halide compound is a semiconductor material. [ABSTRACT FROM AUTHOR]

Hydrazine (N 2 H 4) is a very important chemical reagent which has been widely used in the fields of chemistry industry, aerospace, pesticide production and others. However, N 2 H 4 is highly toxic and prone to induce a variety of diseases. Hence, we designed two fluorescent probes (CH–NO1 , CH–NO2) based on chloro-hydroxyl-merocyanine (CHMC) with similar recognition groups. The two probes were synthesized by a simple reaction coupling between CHMC dye and two alkyl bromine compounds. Both probes showed specific off-on response to N 2 H 4 in aqueous solution with nanomolar LOD (28 nM for CH–NO1 and 38 nM for CH–NO2), and without interference by a range of amino acids, anions and cations. Moreover, CH–NO1 can be used for both environmental and biological monitoring of N 2 H 4. • Specific off-on switching response to N 2 H 4 with near infrared luminescence. • The probe showed nanomolar LOD for detecting N 2 H 4. • Allowed to sense N 2 H 4 in both environmental and biological monitoring. [ABSTRACT FROM AUTHOR]