Bromine Atoms Research Articles

A kinetic study of the reactions of atomic bromine with the trimethylbenzenes.

This work presents the results of kinetic measurements for the reactions of atomic bromine with the three isomers of trimethylbenzene at temperatures from 295 K to 354 K and at pressures close to atmospheric. The atomic bromine was produced by photolysis of Br2 in a thermostated Pyrex chamber as described in our previous work. The reactants were present as dilute mixtures in argon with Br2 in sufficient excess to scavenge the free radical products of the initiation step. Chemical analysis was by gas chromatography and the rate coefficients were calculated from the chromatographic results using the relative rate method. The experimentally measured temperature dependence of the rate coefficients for the reactions of Br with the trimethylbenzenes is given in the units cm3 molec.-1 s-1 by: 1,2,3-trimethylbenzene + Br, log10(k) = -9.57 ± 0.43 - (996 ± 134)/T; 1,2,4-trimethylbenzene + Br, log10(k) = -9.74 ± 0.29 - (968 ± 91)/T; 1,3,5-trimethylbenzene + Br, log10(k) = -9.87 ± 0.26 - (1079 ± 85)/T. The enthalpies and entropies of activation for these reactions are compared to those for the reactions of Br with toluene and the xylenes.

An insight into the hydrogen bonding, halogen bonding and chalcogen bonding interactions in manganese(iii) complexes with N2O2donor salicylidine Schiff base ligands.

Four manganese(iii) complexes, [MnL1(H2O)2]ClO4·H2O (1), [MnL2(H2O)2]ClO4 (2), [MnL3(DMSO)(H2O)]ClO4 (3) and [MnL4(DMSO)(H2O)]ClO4 (4), where H2L1 = N,N'-bis(5-bromosalicylidene)-1,3-diaminopropane, H2L2 = 2,2-dimethyl-N,N-bis(3-methyloxysalicylidene)-1,3-diaminopropane, H2L3 = N,N'-bis(5-chlorosalicylidene)-2,2-dimethyl-1,3-diaminopropane and H2L4 = 2-hydroxy-N,N'-bis(3-ethyloxysalicylidene)-1,3-diaminopropane are tetradentate N2O2-donor ligands and DMSO = dimethyl sulfoxide, have been synthesized and characterised by elemental analysis, IR and UV-vis spectroscopy and single-crystal X-ray diffraction studies. All are monomeric complexes. Complex 1 crystallises in orthorhombic space group P212121, complex 3 crystallises in triclinic space group P-1, whereas complexes 2 and 4 crystallize in monoclinic space groups, C2/c and C2/m respectively. In all the complexes, manganese(iii) has a six-coordinated pseudo-octahedral geometry in which imine nitrogen atoms and phenolate oxygen atoms of the deprotonated di-Schiff base constitute the equatorial plane. In complexes 1 and 2, water molecules are present in the fifth and sixth coordination sites in the axial positions while in complexes 3 and 4 they are occupied by one water and one DMSO. The coordinated water molecules initiate hydrogen-bonded networks in all complexes. DFT calculations have been carried out to analyze two aspects of these complexes viz. the formation of halogen (HaB) and chalcogen bonding (ChB) interactions in complexes 1 and 3 where the electron donor is the perchlorate anion and the acceptor either bromine or chlorine atoms for the HaBs and the sulfur atom of the coordinated DMSO for the ChB. In addition, other intermolecular effects are discussed in the solid state for complexes 1, 2 and 4, where the hydrogen atoms of the coordinated water molecules interact with the electron rich cavities formed by the phenolate and alkyloxy oxygen atoms of the Schiff-base ligand.

Effect of substitution on deep-blue Ir(III) N-heterocyclic carbene (NHC) emitters.

The development of Ir(III)-NHC phosphors that display deep-blue luminescence without sacrificing the high photoluminescence quantum yield (PLQY) has become a pivotal area of research. In this respect, two novel deep-blue Ir-NHC emitters (C1 and C2) with strategically designed pro-carbenic imidazolium ligands (L1 and L2) incorporating a heavy bromine atom at the ligand-scaffold were synthesized in good yields (∼80% for L1, L2 and 65% for C1, C2). The ground and excited state properties of the complexes were photophysically determined and the results were found to be in accordance with theoretical calculations at the DFT and TD-DFT levels. Due to the strong σ-donation of the carbene ligands, complexes C1 and C2 displayed oxidation at low anodic potentials. Both the complexes showed deep-blue emission either in solution (λem ∼ 400-425 nm) or as PMMA-doped films of varying concentrations (λem ∼ 400 nm) with an ∼15 times enhanced PLQY with respect to benchmark Ir-NHC complexes. The strategy of incorporating the heavy bromine atom to reduce the molecular vibrations in C1 and C2 was further supported by ∼250 times reduced non-radiative decay constants (knr) and Huang-Rhys constants of C1 and C2 in comparison to those of the benchmark complexes. These facts were also supported by triplet frequency calculations of C1 and C2 to identify the absence of vibrations.

Dimeric tetrabromo-p-quinodimethanes: synthesis and structural/electronic properties.

Despite their great potential as molecular building blocks for organic synthesis, tetrabromo-p-quinodimethanes (TBQs) are a relatively unknown family of compounds. Herein, we showcase a series of five derivatives incorporating two tetrabromo-anthraquinodimethane (TBAQ) units linked by π-conjugated spacers of different nature and length. The resulting dimers TBQ1-5 are fully characterised by means of thorough spectroscopic measurements and theoretical calculations. Interestingly, owing to the steric hindrance imposed by the four bulky bromine atoms, the TBAQ fragments adopt a characteristically warped geometry, somehow resemblant of a butterfly, and the novel dimers show a complex NMR pattern with signal splittings. To ascertain whether dynamic processes regarding fluxional inversion of the butterfly configurations are involved, first-principles calculations assessing the interconversion energy barriers are performed. Three possible stereoisomers are predicted involving two diastereomers, thus accounting for the observed NMR spectra. The rotational freedom of the TBAQ units around the π-conjugated linker influences the structural and electronic properties of TBQ1-5 and modulates the electronic communication between the terminal TBAQ moieties. The role of the linker on the electronic properties is investigated by Raman and UV-vis spectroscopies, theoretical calculations and UV-vis measurements at low temperature. TBQ1-5 are of interest as less-explored structural building precursors for a variety of scientific areas. Finally, the sublimation, self-assembly and reactivity on Au(111) of TBQ3 is assessed.

Синтез и электрофильная гетероциклизация 3 алкенилсульфанил-5-фенил-1,2,4-триазинов под дейст-вием иода и брома

Derivatives of 1,2,4-triazine-3-thione are interesting research objects due to a wide range of their applications: drugs, optical substances, precursors for synthesis of new pyridine systems by the Diels-Alder reaction. In the present study, using alkylation of 5-phenyl-2,3-dihydro-1,2,4-triazine-3-thione (1) by 3-chloro-2-methyl-propene, 2,3-dibromopropene-1, 1-bromo-3-methylbut-2-ene and 4-brombut-1-ene, we have obtained 3-(2-methylprop-1-enyl)-, 3-(2-bromoprop-1-enyl)-, 3-prenylsulfanyl- and 3-butenylsulfanyl-5-phenyl-1,2,4-triazines (2a-d), previously unknown. In the 1H NMR spectrum of compound 2b, the shifts of the signal of pro-tons of the SCH2 group and the signal of protons of the vinyl group into a weak field by 0.48 ppm and 0.60 ppm can be observed, compared to the similar signals in the spectrum of 3-allylsulfanyl-5-phenyl-1,2,4-triazine. This may be due to the bromine atom in the allyl fragment. The weakest-field signal in the 13C NMR spectra of compounds 2a-d in the region of 171.86–173.68 ppm refers to the aromatic carbon atom of the triazine cycle in the third position (C-3), bound to a sulfur atom and two nitrogen atoms. New condensed heterocyclic systems of ionic type with a bridging nitrogen atom have been synthesized by electrophilic heterocyclization of methallyl-, bromallyl-, prenyl- and butenyl sulfides 2a-d. At the same time, [1,3]thiazolo[3,2-b][1,2,4]triazinium halides have been obtained by heterocyclization of compounds 2a,2b, and [1,3]thiazino[3,2–b][1,2,4]triazinium halides have been produced by heterocyclization of com-pounds 2c,2d. In the 1H NMR spectra of triazinium halides, a characteristic shift of the signal of the H-6 aromatic proton to the weak field region is observed in comparison with the similar sig-nal in the spectrum of the initial 2a-d sulfides. In the 13C NMR spectra of triazinium halides, there is a shift in the signal of the aromatic carbon atom associated with a sulfur atom and two nitrogen atoms (in the region of 162.56-172.42 ppm), which can be explained by the appearance of a positively charged nitrogen atom in their structure.

Regiodivergent (3 + 2) annulation reactions of oxyallyl cations.

We report a new method for the regiodivergent dearomative (3 + 2) reaction between 3-substituted indoles and oxyallyl cations. Access to both regioisomeric products is possible and is contingent on the presence or absence of a bromine atom on the substituted oxyallyl cation. In this way, we are able to prepare molecules that contain highly-hindered, stereodefined, vicinal, quaternary centers. Detailed computational studies employing energy decomposition analysis (EDA) at the DFT level establishes that regiochemical control arises from either reactant distortion energy or orbital mixing and dispersive forces, depending on the oxyallyl cation. Examination of the Natural Orbitals for Chemical Valence (NOCV) confirms that indole acts as the nucleophilic partner in the annulation reaction.

Copper-mediated bromine atom transfer radical cyclisation of unactivated alkyl bromides.

The atom transfer radical cyclisation of unactivated alkyl bromides was realized by using a catalytic system of CuBr and Me6-TREN. This protocol is applicable to the preparation of five-membered rings from unsaturated primary and secondary bromides.

Incorporation of a bromine atom into DNA-related molecules changes their electronic properties.

To understand the mechanism underlying the high radio-sensitisation of living cells possessing brominated genomic DNA, X-ray photoelectron spectroscopy (XPS) using synchrotron X-rays with energies of 2000 or 2500 eV was used to study brominated and nonbrominated nucleobases, nucleosides and nucleotides. The bromine atom significantly reduced the energy gap between the valence and conduction states, although the core level states were not greatly affected. This finding was supported by quantum chemical calculation for the nucleobases and nucleosides. Our findings strongly indicate that the energy gaps between the valence and conduction levels of the molecules are significantly reduced by bromination. Furthermore, the brominated molecules are more likely to produce inelastic scattering low energy electrons upon exposure to 2000 or 3000 eV X-rays. This modification of electronic properties around the brominated group may both facilitate electron transfer to the brominated site in DNA and increase the probability of reaction with low energy electrons. These processes can induce DNA damage, presumably resulting in debromination of the uracil moiety and a subsequent cytotoxic effect.

SYNTHESIS AND PRECLINICAL STUDY OF ANTIOXIDANT ACTIVITY OF [1,2,4]TRIAZOLO[1,5-A]PYRIDINE DERIVATIVES

Purpose. Synthesis and study of antioxidant properties of [1,2,4]triazolo[1,5-a]pyridine derivatives and their potential toxicity using preclinical diagnostic methods. Methodology. Derivatives of [1,2,4]triazolo[1,5-a]pyridine were synthesized on the basis of 2-aminopyridines and ethyl isothiacyanatocarbonate, with subsequent cyclization of intermediate adducts. The resulting 2-amino[1,2,4]triazolo[1,5-a]pyridines were reacted with isoamyl nitrite in the presence of CuHal2, which led to the synthesis of volatile 2-halogeno[1,2,4]triazolo[1,5- a]pyridine. The toxicity of the obtained compounds was studied by the degree of hemolysis of erythrocytes in a hypotonic NaCl solution. The intensity of free-radical oxidation of lipids was assessed spectrophotometrically by the formation of TBА-active products. The antioxidant activity of the substances was determined by inhibiting the oxidation of adrenaline under conditions of artificial oxidative stress. Scientific novelty. For the first time, the antioxidant activity of the [1,2,4]triazolo[1,5-a]pyridine derivatives described in the paper was investigated and their toxicity was studied according to the degree of hemolysis of erythrocytes in a hypotonic NaCl solution. Conclusions. The in vitro cytotoxicity study model showed that compounds 5a and 5b, which contain bromine atoms in the 2, 5, and 7 positions of the pyridinotriazole heterosystem, exert the greatest influence on the stability of erythrocyte membranes. The study of antioxidant activity showed that the highest values of antioxidant activity are characteristic of compounds of the 4a-d series, namely compounds 4b and 4c, which are characterized by the presence of an amino group in the 2nd position and the presence of a bromine atom as a substitute in the 1st and 5th positions of the pyridine fragment of the heterosystem. The dynamics of antioxidant activity on the model of inhibition of adrenaline oxidation confirms the opinion about the lowest toxicity and the highest ability to inhibit the formation of reactive oxygen species of compounds 4b and 4c (40.16 and 38.82% relative to ionol). So, with the use of preclinical diagnostic methods, we proved the presence of physicochemical activity in a number of investigated compounds. 2-amino-[1,2,4]triazolo[1,5a]pyridine derivatives with a bromine atom as a substitute in the pyridine fragment of the molecule should be considered as potential antioxidants in the future, and the studied condensed system can be considered a promising heterocyclic framework for creating potential antioxidant agents.

Synthesis and Antimicrobial Activity Of Nitrogen-Containing Anthraquinone Derivatives

New substituted anthraquinones with amino derivations fragments were synthesized through the substitution of bromine atom by different amines using the Ullmann coupling reaction. Obtained compounds based on anthraquinone used for experimental antimicrobial studies. The structure of the synthesized compounds was confirmed by LC-MS and 1H, 13C NMR spectroscopy. Studies on planktonic microorganisms have shown that the first synthesized anthraquinone derivatives have an inhibitory effect against bacteria and fungi. The triazene 1-(3-(benzoic acid(triaz-1-en-1-ol(-4-(1H-imidazol-1-yl(-9,10-dioxo-9,10-dihydroanthracene -2-sulfonic acid, have wide spectrum of activity, growth retardation zones against gram-positive microorganisms in the range of 8.41-11.5 mm, gram-negative bacteria 5.87-8.18 mm, fungi of the genus Candida 5.81-7.48 mm. The high antimicrobial activity of this compound is probably due to the presence of benzoic acid in its molecule.

Elaboration of novel urea bearing schiff bases as potent in vitro anticancer candidates with low in vivo acute oral toxicity

A novel series of urea Schiff base derivatives were synthesized via the condensation of o-phenylenediamine, naphthyl isocyanate and appropriate aryl aldehyde. The results of the in vitro cytotoxic activities of compounds 5a–h against cancer cells lines PC3, SKOV-3 and HeLa, revealed that almost all compounds exhibited good to moderate activities Compound 5g owing bromine atom at p-position displayed higher activity compared to homolog 5b possessing chlorine atom due to adequate diameter of bromine which is more favourable than chlorine for the inhibition activity. In addition, compound 5h is the best candidate of this series exhibiting excellent activity for three cancer cells lines. Compound 5h demonstrated also an excellent activity with IC50 value of 0.6±0.3μg/mL for prostate cancer cell line PC3 and it is considered more effective than the standard drug doxorubicin Dox (IC50 = 2.6±0.03μg/mL). The most active compound 5h displayed the best activity against ovarian cancer cell line SKOV3 with IC50 = 1.8±0.2μg/mL. This results are higher than clinically used drug Dox (IC50. 2.2±0.02μg/mL). The results of screening activities cytotoxic effect toward cervix cancer cell line HeLa, affirm that compound 5h manifest an activity with IC50 value of 2.2±0.4μg/mL comparable to Dox (IC50. 1.9±0.04μg/mL). In the current study, in vivo acute oral toxicity assessment of urea Schiff base hybrid compounds 5a – h indicated that there was no mortality on treated female mice during 14 days assessment test compared with the vehicle-treated group confirming the safety with LD50 greater than 2000 mg/kg. In the actual study, the results affirmed that compounds 5a–h manifested in vivo no toxicity to saint cells, the compounds 5b, 5g and 5h presented higher anticancer activities against three cancer cells which authorizes promoters to use them as candidate anticancer agents.

DC slice ion imaging of the ultraviolet photodissociation of 2-bromohexane

The ultraviolet photodissociation dynamics of 2‑bromohexane around 234 nm has been investigated using the DC slice velocity map imaging technique. Relative quantum yield of the ground state bromine atom is measured to be 0.961. By analyzing the slice images, we can obtain the speed and angular distributions of the ground state and excited state bromine atoms. The speed distribution contains two Gaussian components, which are attributed to two dissociation channels. The high translational energy component is formed via the direct dissociation along the C–Br bond. Nevertheless, the low translational energy component is formed via the multidimensional dissociation along the C–Br bond coupling with the bending modes. The alkyl radical branching promotes the multidimensional dissociation. What’s more, the contribution of the electric-dipole allowed3Q1, 3Q0 and 1Q1 states to the product formation is also discussed. The nonadiabatic 1Q1←3Q0 transition plays a significant role in the dissociation process.

Pd/Cu-Catalyzed Cross-Coupling of Bis(2-bromovinyl) Selenides with Terminal Acetylenes: Unusual Involvement of Selanyl Function in the Sonogashira Reaction

The Pd/Cu-catalyzed Sonogashira reaction of (E,E)-bis(2-bromovinyl) selenide and (E,E)-bis(1-bromo-1-hexen-2-yl) selenide with terminal alkynes was found to proceed at room temperature involving both bromine atoms and the selanyl function. As a result, new bis-(1,3-enynyl) selenides and enediyne hydrocarbons are formed with a complete retention of the stereoconfiguration of the initial selenides. Due to steric hindrances in the cross-coupling at the selenyl function in the case of (E,E)-bis(1-bromo-1-hexen-2-yl) selenide, the second process is realized to a lesser extent than with unsubstituted (E,E)-bis(2-bromovinyl) selenide.

Cost‐Effective Vat Orange 3‐Derived Organic Cathodes for Electrochemical Energy Storage

AbstractOrganic compounds are desirable alternatives for sustainable lithium‐ion battery electrodes. Vat orange 3 (VO3, 4,10‐dibromoanthanthrone) is a highly cost‐effective organic dye containing two conjugated carbonyl groups, which can reversibly accept two electrons. The skeleton also contains two bromine atoms, which allows easy incorporation of the anthanthrone unit into polymers through simple reactions. In this work, we report the preparation of organic cathodes derived from the low‐costVO3dye for lithium‐organic batteries (LOBs). The results show that polymericVO3‐based materials exhibit remarkably high cyclability and rate performance, because of their effective suppression of dissolution. In particular, the sulfide polymer poly(anthanthrone sulfide) (PATS) shows an initial large‐current (0.2 A g−1) discharge capacity of 133 mAh g−1at a potential near 2.4 V. The capacity reaches a maximum capacity of 147 mAh g−1after 24 cycles and is maintained at 132 mAh g−1after 300 cycles. Moreover, a full battery cell with the structure:PATScathode||graphite anode, further delivers an impressive electrochemical performance with an energy density up to 237 Wh kg−1along with an output voltage of 2.3 V. The present study initiates the use ofVO3‐based organics, which show promising potential for future application in LOBs on a large scale.

Replenishment in the Family of Rhenium Chalcobromides; Synthesis and Structure of Molecular {Re4S4}Br8(TeBr2)4, Dimeric [{Re4S4}Br8(TeBr2)3]2, and Polymeric {Re4S4}Br8 Compounds Based on the {Re4S4}8+ Tetrahedral Cluster Core.

We have obtained three new rhenium(IV) chalcobromides belonging to the homologous series {Re4S4}Br8(TeBr2)n (n = 0, 3, 4): a molecular complex {Re4S4}Br8(TeBr2)4 (1), a dimeric complex [{Re4S4}(TeBr2)3Br7(μ-Br)]2 (2), and a two-dimensional (2D) polymeric compound {Re4S4}Br8 (3). Compound 1 is isotypic to the already known {Re4Te4}(TeBr2)4Br8, while 2 and 3 exhibit a new type of binding of tetrahedral clusters via μ-Br bridges. Compounds were characterized by X-ray single-crystal diffraction, X-ray powder diffraction, and thermal and elemental analyses. In compound 2, two tetrahedral cluster cores {Re4S4}8+ are linked together forming a dimer through two Re-μ-Br-Re bridges. Calculations of the electron localization function (ELF) showed that there is no covalent interaction between rhenium atoms of neighboring clusters. In compound 3, each rhenium atom of the {Re4S4}8+ core is coordinated by three Br ligands: one terminal Br and two bridging μ-Br ligands. As a result, eight bridging bromine atoms link {Re4S4}8+ cluster cores into goffered layers. {Re4S4}Br8 is the new stable rhenium(IV) thiobromide, the first discovered in the Re-S-Br system, along with the already known octahedral rhenium(III) thiobromides Re6S4+xBr10-2x (x = 0-4).

Apparent Reactivity of Bromine in Bromochloramine Depends on Synthesis Method: Implicating Bromine Chloride and Molecular Bromine as Important Bromine Species.

The chloramination of bromide containing waters results in the formation of bromine containing haloamines: monobromamine (NH2Br), dibromamine (NHBr2), and bromochloramine (NHBrCl). Many studies have directly shown that bromamines are more reactive than chloramines in oxidation and substitution reactions with organic water constituents because the bromine atom in oxidants is more labile than the chlorine atom. However, similar studies have not been performed with NHBrCl. It has been assumed that NHBrCl has similar reactivity as bromamines with organic constituents in both oxidation and substitution reactions because NHBrCl, like bromamines, rapidly oxidizes N,N-diethyl-p-phenylenediamine. In this study, we examined the reactivity of NHBrCl with phenol red to determine if NHBrCl reacts as readily as bromamines in an isolated substitution reaction. NHBrCl was synthesized two ways to assess whether NHBrCl or the highly reactive intermediates, bromine chloride (BrCl) and molecular bromine (Br2), were responsible for bromine substitution of phenol red. NHBrCl was found to be much less reactive than bromamines with phenol red and that BrCl and Br2 appeared to be the true brominating agents in solutions where NHBrCl is formed. This work highlights the need to reexamine what the true brominating agents are in chloraminated waters containing bromide.

Preparation of mesoporous poly(fullerene oxide) framework by thermal [3 + 2] cycloadditions and its application as a semiconductor photocatalyst

We report the formation of an interconnected, three-dimensional, mesoporous polymeric fullerene oxide framework via thermal [3 + 2] cyclo-additions of monomeric C60 and fullerene oxides (C60On), formed upon thermal decomposition of C60Br24, causing the eliminations of bromine atoms in an oxygen atmosphere at an elevated temperature of 200 °C. The newly formed mesoporous fullerene oxide framework is found to be a low bandgap semiconductor capable of acting as a photocatalyst similar to graphitic C3N4. The sunlight-assisted photocatalytic degradation of the methylene blue dye is demonstrated. To have a better understanding of the mechanism of the [3 + 2] cyclo-additions of monomeric C60 and fullerene oxides, a theoretical investigation has been carried out and the energetics of the reaction C60O + C60 → C120O is calculated.

Potential deterioration of ozone pollution in coastal areas caused by marine-emitted halogens: A case study in the Guangdong-Hong Kong-Macao Greater Bay Area

Ozone (O3) is one of the most important air pollutants worldwide in terms of its great damage to human health and agriculture. Previous studies show that marine-emitted halogens significantly influence O3 concentrations, mainly through the consumption of O3 by bromine and iodine atoms. In this study, we investigate the temporal variation at finer time scales (daily and hourly) than previous studies (annual or monthly) to better characterize the influence of marine-emitted halogens on coastal O3. In contrast to previous studies that mainly reported a decrease in O3, our results show significant temporal variations in halogen-induced O3 changes. More specifically, the halogen-induced decrease in coastal O3 in southern China is concentrated on clean days, while an unexpected increase in some regions of up to >10 ppbv could occur on polluted days. On polluted days, the activation of particulate chloride (Cl−) in sea salt aerosol (SSA) is effective due to the high level of dinitrogen pentoxide (N2O5) that is formed from the reactions of O3 and nitrogen dioxide (NO2). In addition, the wind fields are unfavorable for the transport of marine air masses with large O3 depletion inland. These two factors together result in the increase in hourly and MDA8 O3 on polluted days in some regions in the GBA. The locations of O3 increases are controlled by the distribution of nitryl chloride (ClNO2) at sunrise, which is influenced by O3 and NO2 during the previous night. As a result, the increase in O3 is a continuation of the O3 pollution from the previous day, and the whole area is under potential threat of this worsening pollution.

Bromophenol Induced Multiple Stress Responses in Rice Plants: Impact of Doses and Congener Structures.

Bromophenols (BPs) have both natural and artificial sources in the environment and are frequently detected in plants. Herein, the ubiquitous 2,4,6-TriBP was hydroponically exposed to rice seedlings at two concentrations (0.2 and 2.0 mg/L) to characterize the dose-dependent abiotic stress responses of rice plants to BPs. The 2,4,6-TriBP induced oxidative damage to rice roots and subsequently inhibited plant transpiration and growth at the end of exposure in both concentrations. Moreover, the gene expression of OsUGT72B1 and the activity of glycosyltransferases of exposed rice roots were 2.36-to-4.41-fold and 1.23-to-1.72-fold higher than that of the blank controls after 24 h, following the formation of glycoconjugates in response to 2,4,6-TriBP exposure. It was notable that the glycosylation rates also showed a dose-effect relationship in rice roots. One and six glycoconjugates of 2,4,6-TriBP were detected in 0.2 and 2.0 mg/L exposure groups, respectively. Considering the detected species of glycoconjugates for four other types of BPs, the numbers of bromine atoms were found to dramatically affect their glycosylation process in rice plants. These results improve our fundamental understanding of the impact of congener structures and exposure concentrations of organic contaminants on the glycosylation process in response to phytotoxicity.

Designing metal chelates of halogenated sulfonamide Schiff bases as potent nonplatinum anticancer drugs using spectroscopic, molecular docking and biological studies

In this contribution, five Ni(II) complexes have been synthesized from sulfonamide-based Schiff bases (SB1–SB5) that comprise bromo or iodo substituents in the salicylidene moiety. The chemical structures of these compounds were extensively elucidated by different analytical and physicochemical studies. All ligands act as bidentate chelators with ON binding mode yielding octahedral, square planar, or tetrahedral geometries. The phenolic OH at δ 12.80 ppm in the free Schiff base SB2 vanishes in the 1H NMRspectrum of diamagnetic complex [Ni(SB2–H)2] favoring the OH deprotonation prior to the chelation with Ni(II) ion. The appearance of twin molecular ion peaks ([M − 1]+ and [M + 1]+) is due to the presence of bromine isotopes (79Br and 81Br) in the mass spectra of most cases. Also, the thermal decomposition stages of all complexes confirmed their high thermal stability and ended with the formation of NiO residue of mass 6.42% to 14.18%. Besides, antimicrobial activity and cytotoxicity of the ligands and some selected complexes were evaluated. Among the ligands, SB4 showed superior antimicrobial efficacy with MIC values of 0.46, 7.54, and 0.95 µM against B. subtilis, E. coli, and A. fumigatus strains, respectively. The consortium of different substituents as two bromine atoms either at positions 3 and/or 5 on the phenyl ring and a thiazole ring is one of the reasons behind the recorded optimal activity. Moreover, there is a good correlation between the cytotoxicity screening (IC50) and molecular docking simulation outcomes that predicted a strong binding of SB2 (16.0 μM), SB4 (18.8 μM), and SB5 (6.32 μM) to the breast cancer protein (3s7s). Additionally, [Ni(SB4–H)2] (4.33 µM) has nearly fourfold potency in comparison with cisplatin (19.0 μM) against breast carcinoma cells (MCF-7) and is highly recommended as a promising, potent, as well as low-cost non-platinum antiproliferative agent after further drug authorization processes.