Bromine Atoms Research Articles

<i>N</i>‐Oxide‐Catalyzed Six‐Membered Ring Bromo‐etherification of ε‐Alkenyl Alcohols

A six‐membered ring bromo‐etherification of ε‐alkenyl alcohols using <i>N</i>‐oxide catalyst was developed to furnish 2‐bromomethyl‐6‐substituted tetrahydropyrans with <i>cis</i>‐selectivity and 3‐bromomethyl isochromans in high yields. DFT calculations indicate that the NMO catalyst enhances the electrophilicity of the bromine atom on NBS via two hydrogen‐bonding interactions after the formation of the NMO‐NBS complex.

1,4-Benzodioxane Substituted Aza-BODIPY: Towards Photostable yet Efficient Triplet Photosensitizer.

We report herein the synthesis of aza-BODIPY substituted with 1,4-benzodioxane-6-yl substituents at 3,5 positions of the chromophore system. Both pyrrole rings of the aza-BODIPY in question were substituted with bromine atoms in order to induce highly desirable photophysical properties, such as highly populated excited triplet state (T1) and long excited triplet-state lifetime (τT) of 21 μs. The photosensitized oxygenation of a model compounds, viz. DPBF, points to a high singlet oxygen and/or other ROS formation quantum yield of 0.42. The photosensitizer studied exhibited an absorption band within the so-called "therapeutic window", with λabs 678 nm. As estimated by CV/DPV measurements the 1,4-benzodioxane-6-yl substituted aza-BODIPYs studied exhibited a multi-electron oxidations at a relatively low potentials (Eox), pointing to the very good electron-donating properties of these molecules. High photostability and thermal stability was observed for all compounds studied. The good singlet oxygen quantum yield measured combined with an exceptional photostability makes this aza-BODIPY a promising candidate for applications such as photocatalysis and photodynamic therapy (PDT).

An n-Doping Cross-Linkable Quinoidal Compound as an Electron Transport Material for Fully Stretchable Inverted Organic Solar Cells.

The photocatalytic activity and inherent brittleness of ZnO, which is commonly used as an electron transport layer (ETL) in inverted organic solar cells (OSCs), have impeded advancements in device stability and the development of fully stretchable OSCs. In this study, an intrinsically stretchable ETL for inverted OSCs through a side-chain cross-linking strategy has been developed. Specifically, cross-linking between bromine atoms on the side chains of a quinoidal compound and the amino groups in polyethylenimine resulted in a film, designated QBr-PEI-50, with high electrical conductivity (0.049 S/m) and excellent stretchability (crack-onset strain>45 %). When used as the ETL in inverted OSCs, QBr-PEI-50 was markedly superior to ZnO in terms of device performance and stability, yielding a power conversion efficiency (PCE) of 18.27 % and a T80 lifetime exceeding 10000 h. Moreover, incorporation of QBr-PEI-50 in fully stretchable inverted OSCs yielded a PCE of 14.01 %, and 80 % of the initial PCE was maintained after 21 % strain, showcasing its potential for wearable electronics.

An n‐Doping Cross‐Linkable Quinoidal Compound as an Electron Transport Material for Fully Stretchable Inverted Organic Solar Cells

AbstractThe photocatalytic activity and inherent brittleness of ZnO, which is commonly used as an electron transport layer (ETL) in inverted organic solar cells (OSCs), have impeded advancements in device stability and the development of fully stretchable OSCs. In this study, an intrinsically stretchable ETL for inverted OSCs through a side‐chain cross‐linking strategy has been developed. Specifically, cross‐linking between bromine atoms on the side chains of a quinoidal compound and the amino groups in polyethylenimine resulted in a film, designated QBr‐PEI‐50, with high electrical conductivity (0.049 S/m) and excellent stretchability (crack‐onset strain>45 %). When used as the ETL in inverted OSCs, QBr‐PEI‐50 was markedly superior to ZnO in terms of device performance and stability, yielding a power conversion efficiency (PCE) of 18.27 % and a T80 lifetime exceeding 10000 h. Moreover, incorporation of QBr‐PEI‐50 in fully stretchable inverted OSCs yielded a PCE of 14.01 %, and 80 % of the initial PCE was maintained after 21 % strain, showcasing its potential for wearable electronics.

Preparation of Br-terminated Si(100) and Si(111) surfaces and their use as atomic layer deposition resists

In area-selective processes, such as area-selective atomic layer deposition (AS-ALD), there is renewed interest in designing surface modification schemes allowing to tune the reactivity of the nongrowth (NG) substrates. Many efforts are directed toward small molecule inhibitors or atomic layers, which would modify selected surfaces to delay nucleation and provide NG properties in the target AS-ALD processes allowing for the manufacturing of smaller sized features than those produced with alternative approaches. Bromine termination of silicon surfaces, specifically Si(100) and Si(111), is evaluated as a potential pathway to design NG substrates for the deposition of metal oxides, and TiO2 (from cycles of sequential exposures of tetrakis-dimethylamido-titanium and water) is tested as a prototypical deposition material. Nucleation delays on the surfaces produced are comparable to those on H-terminated silicon that is commonly used as an NG substrate. However, the silicon surfaces produced by bromination are more stable, and even oxidation does not change their chemical reactivity substantially. Once the NG surface is eventually overgrown after a large number of ALD cycles, bromine remains at the interface between silicon and TiO2. The NG behavior of different crystal faces of silicon appears to be similar, albeit not identical, despite different arrangements and coverage of bromine atoms.

Inside Cover Picture

The BiOCl0.5Br0.5 with flower‐like structure exhibits the layered structure, in which the self‐hybridization of chlorine and bromine atoms induces an intensified internal electric field and wider Van der Waals gap, providing a fast diffusion path for K+ ion. Combining the decreasing of the electron polarons induced by the hybridized structure and the in situ formation of hole‐like polarons caused by the dynamic K+ ion‐halogen atoms correlation, the BiOCl0.5Br0.5 anode exhibits a stimulative K+ ion diffusion kinetics, thus enabling a high electrochemical performance in potassium‐ion batteries. More details are discussed in the article by Wu et al. on pages 2589—2598.image

Regulation of TADF and RTP Dual Emission via Internal and External Heavy-Atom Effects.

Organic materials with thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) dual emission have attracted great attention in recent years, but the regulation mechanism via internal and external heavy atoms is not clear enough. Here, we carry out a systematic theoretical investigation on the photophysical properties of the materials by introducing aliphatic or aromatic bromine atoms. The molecule with aromatic bromine atoms exhibits obvious TADF owing to the effective reverse intersystem crossing (RISC) with matchable energy levels and enhanced spin orbit couplings, the molecule with aliphatic bromine atoms shows a long RTP lifetime because of the reduced nonradiative transition of triplet excitons, and the molecule with both aliphatic and aromatic bromine atoms presents balanced TADF and RTP emissions thanks to the synergy internal and external heavy-atom effects. Besides, the internal and external heavy atoms induce multisite intermolecular interactions, effectively suppressing the nonradiative process in the solid phase. The efficient RISC process and the suppressed nonradiative process of triplet excitons should be key to regulating the dual emission property. These findings and insights are of great importance for revealing the structure-performance relationship, providing theoretical guidance for the design of TADF and RTP dual emission molecules via internal and external heavy-atom effects.

Mol-ecular structure of tris-[(6-bromo-pyridin-2-yl)meth-yl]amine.

Coordination compounds of polydentate nitro-gen ligands with metals are used extensively in research areas such as catalysis, and as models of complex active sites of enzymes in bioinorganic chemistry. Tris(2-pyridyl-meth-yl)amine (TPA) is a tripodal tetra-dentate ligand that is known to form coordination compounds with metals, including copper, iron and zinc. The related compound, tris-[(6-bromo-pyridin-2-yl)meth-yl]amine (TPABr3), C18H15Br3N4, which possesses a bromine atom on the 6-position of each of the three pyridyl moieties, is also known but has not been heavily investigated. The mol-ecular structure of TPABr3 as determined by X-ray diffraction is reported here. The TPABr3 molecule belongs to the triclinic, P space group and displays interesting intermolecular Br⋯Br interactions that provide a stabilizing influence within the molecule.

Inorganic/organic sublattice roles in band edge photodynamics of isoelectronically substituted hybrid semiconductors

Zero-dimensional organic–inorganic hybrid metal halides are unique semiconductors with fruitful physical properties. Usually, only the inorganic polyhedrons dominate the band edge electronic and photophysical properties of such hybrid semiconductors, whereas the organic components mainly act as structure-stabilizing units. Herein, we study the electronic structures and photodynamics of isoelectronically Br-substituted (I) zero-dimensional organic–inorganic copper halide semiconductors (C9H14N)3Cu3(BrxI1−x)6. They are composed of both inorganic [Cu3(BrxI1−x)6]3− units and organic C9H14N+ skeletons. It is surprising to find that unlike usual organic–inorganic metal halides, although the heavily isoelectronic substitution of halogen atoms in the (C9H14N)3Cu3I6 crystal leads to significant shrinkage of the lattice, it does not remarkably alter the bandgap and luminescence peak owing to the site-projected density of states as revealed by the density functional theory calculation. The inorganic units dominate the valence band edge quantum states, whereas the organic skeletons dominate the conduction-band edge states. However, the isoelectronic substitution significantly lowers the symmetry of the crystal, and as a result, the quantum transition probability at the band edge increases first and decreases then with increasing concentration of substituting bromine atoms. The (C9H14N)3Cu3(BrxI1−x)6 crystals exhibit dual-band luminescence with large Stokes shift and near-unity quantum yield. It arises from the excitons trapped by two kinds of centers. The critical participation of the organic skeletons in the electronic structures and band edge photodynamics refresh our knowledge of their roles in the hybrid semiconductors.

Stonikacidin A, an Antimicrobial 4-Bromopyrrole Alkaloid Containing L-Idonic Acid Core from the Northwestern Pacific Marine Sponge Lissodendoryx papillosa.

Stonikacidin A (1), the first representative of a new class of 4-bromopyrrole alkaloids containing an aldonic acid core, was isolated from the marine sponge Lissodendoryx papillosa. The compound is named in honor of Prof. Valentin A. Stonik, who is one of the outstanding investigators in the field of marine natural chemistry. The structure of 1 was determined using NMR, MS analysis, and chemical correlations. The L-idonic acid core was established by the comparison of GC, NMR, MS, and optical rotation data of methyl-pentaacetyl-aldonates obtained from the hydrolysis products of 1 and standard hexoses. The L-form of the idonic acid residue in 1 was confirmed by GC analysis of pentaacetate of (S)-2-butyl ester of the hydrolysis product from 1 and compared with corresponding derivatives of L- and D-idonic acids. The biosynthetic pathway for stonikacidin A (1) was proposed. The alkaloid 1 inhibited the growth of Staphylococcus aureus and Escherichia coli test strains, as well as affected the formation of S. aureus and E. coli biofilms. Compound 1 inhibited the activity of sortase A. Molecular docking data showed that stonikacidin A (1) can bind with sortase A due to the interactions between its bromine atoms and some amino acid residues of the enzyme.

An experimental and theoretical study of coinage bond interaction in a copper(II)/potassium(I) Schiff base complex

A copper(II)/potassium(I) Schiff base polymeric complex has been synthesized and characterized. Salen-type N2O2O2′ donor compartmental Schiff base ligand has been used where copper(II) resides in the inner N2O2 core and potassium (I) sits in the outer O2O2′ core. Single crystal X-ray analysis revealed that the unintended formation of a disordered bromine atom led to Cu⋯Br π-hole coinage bond (CiB) interaction. The energetics regarding the CiB interactions have been rationalized using DFT calculations, QTAIM, and ELF study.

Synthesis, optical properties and self-assemblies of a new halogenated BODIPY dye with long alkoxy chain

A new boron-dipyrromethene (BODIPY) dye modified with two bromine atoms at the 2,6-positions and three hydrophobic p-(dodecyloxy)styryl groups at 3,5,8-positions was designed and synthesized. Its molecular structure was characterized by 1HNMR and MALDI-TOF-MS. The photophysical properties and aggregate behavior of dye 3 in solution were studied by UV–visible absorption and fluorescence spectroscopy. The dye 3 exhibited strong absorption and a high fluorescence quantum yield in different solvents. The self-assembly behaviors were investigated in THF and water mixtures, and the J-aggregates can be formed. Supramolecular self-assembly behavior of dye 3 was confirmed by temperature-dependent UV−Vis absorption. In addition, the self-assembly behavior of dye 3 in liquid-solid interface was studied using scanning tunneling microscopy (STM) and displays highly ordered linear arrangement on HOPG. The self-assembly processes are found to be adjusted by halogen bonding as well as π−π stacking.

Halogen-Functionalized Hole Transport Materials with Strong Passivation Effects for Stable and Highly Efficient Quasi-2D Perovskite Solar Cells.

The performance of quasi-two-dimensional (Q-2D) perovskite solar cells (PSCs) strongly depends on the interface characteristics between the hole transport material (HTM) and the perovskite layer. In this work, we designed and synthesized a series of HTMs with triphenylamine-carbazole as the core structure and modified end groups with chlorine and bromine atoms. These HTMs show deeper highest occupied molecular orbital energy levels than commercial HTMs. This reduced energy band mismatch between the HTM and perovskite layer facilitates efficient charge extraction at the interface. Moreover, these HTMs containing halogen atoms on the end groups could form halogen bonding with the Pb2+ ions at the buried interface of the perovskite layer, effectively passivating defects to suppress nonradiative recombination. Additionally, halogen bonding also contributes to the formation of vertically oriented perovskite crystals with a high quality. By incorporation of chlorohexane-substituted HTMs, the resultant Q-2D PSCs exhibited the highest power conversion efficiency of 21.07%. Furthermore, the devices show improved stability, retaining 97.2% of their initial efficiency after 1100 h of continuous illumination.

Advancements in bandgap engineering: bromide-doped cesium lead perovskite thin films

Perovskite materials have emerged as promising candidates for next-generation photovoltaic devices due to their unique optoelectronic properties. In this study, we investigate the incorporation of bromine into cesium lead mixed iodide and bromide perovskites (CsPbI3(1-x)Br3x) to enhance their performance. By depositing films with varying bromine concentrations (x = 0, 0.25, 0.5, 0.75), we employ a combination of structural and optical characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy, and photoluminescence. Our analysis reveals that introducing bromine leads to structural modifications, influencing the perovskite films’ optical properties and energy gap. Specifically, we observe semiconductor behavior with a tunable energy gap controlled by the intercalation of bromine atoms into the CsPbI3 lattice. Furthermore, heat treatment induces phase transitions in the perovskite films, affecting their optical responses and crystalline quality. SCAPS-1D simulations confirm the improved stability and efficiency of bromine-doped CsPbI3 films compared to undoped counterparts. Our findings demonstrate that bromine incorporation facilitates the formation of highly crystalline perovskite films with reduced trap defects and enhanced carrier transport properties. These results underscore the potential of bromine-doped CsPbI3 perovskites as promising materials for high-performance photovoltaic applications, paving the way for further optimization and device integration.

Gamma‐ray‐induced modification of poly(ethylene terephthalate) and polypropylene solid materials with halogen‐containing olefins for X‐ray CT image contrast enhancement

AbstractIt is known that X‐ray CT of organic polymer materials usually provides low‐contrast images because of the low X‐ray absorption of these materials. In this paper, we describe a new method to enhance the contrast of X‐ray CT images of organic polymer materials. We demonstrate that gamma‐ray irradiation of poly (ethylene terephthalate) (PET) fibers in dichloromethane containing 2‐bromoethyl methacrylate, 2‐chloroethyl methacrylate, or 4‐bromostyrene results in the grafting of halogen‐containing oligomeric chains onto the PET fibers. Focused ion beam scanning electron microscopy (FIB‐SEM) and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) analyses revealed a homogeneous distribution of bromine atoms within the 2‐bromoethyl methacrylate‐modified PET fibers, not only on the surface. This uniform incorporation translated to a significant improvement in X‐ray CT image contrast compared with pristine fibers. Similar treatment of polypropylene pellets also enhanced the contrast of their X‐ray CT images. This is a new simple and effective method to enhance the X‐ray CT image contrast and potentially applicable to various polymer materials including polymer composites and porous polymer materials, readily allowing the observation of their 3D microstructures finely.

Exploring the nonlinear optical properties of hypoxanthinium salts: a structural and computational analysis.

In this study, we detail the synthesis and crystallographic characterization of an unprecedented structure, specifically hypoxanthinium chloride monohydrate ((I) hereafter), which crystallizes in the monoclinic P21/c space group. A comparative analysis was conducted with four related hypoxanthinium salts: hypoxanthinium bromide monohydrate (II), 9-methylhypoxanthinium chloride monohydrate (III), hypoxanthinium nitrate monohydrate (IV), and hypoxanthinium perchlorate monohydrate (V). This analysis has focused mainly on their crystal packing, hydrogen-bonding networks, and non-classical intermolecular interactions, as elucidated by comprehensive Hirshfeld surface and topological analyses. Theoretical investigation of the nonlinear optical (NLO) properties of the hypoxanthinium derivatives (I-V) was performed using the Density Functional Theory (DFT). The crystalline environment was simulated using the iterative Supermolecule method (SM), and the static and dynamics linear refractive index, linear polarizability, second-order hyperpolarizability, and the third-order nonlinear susceptibility at the DFT/CAM-B3LYP/6-311++G(d,p) level were computed. The results for the macroscopic third-order nonlinear susceptibility of (II) was found to equal . By replacing the bromine atom in (II) with a chlorine atom as in (III), the value will be multiplied by 2.16, and therefore these results are large enough to suggest the potential application of these crystals as NLO materials.

Highly electronegative additives suppress energetic disorder to realize 19.19 % efficiency binary organic solar cells

Additive engineering plays an important role in realizing high efficiency organic solar cells (OSCs). The introduction or residual of additives usually increases the energetic disorder of the active layer, which in turn causes a significant reduction of the open-circuit voltage (VOC). Herein, this work proposes a novel additive design approach, that is, using the highly electronegative groups trifluoromethyl and trifluoromethoxy to replace one bromine atom of 1,3,5-tribromobenzene (TBB) to obtain 3,5-Dibromobenzotrifluoride (DBTF) and 3,5-Dibromo-triffluoromethoxybenzene (DBOF). This series of additives can induce strong π-π coupling with acceptor, modulating molecular crystallization and orderly stacking, and thus reducing the non-radiative energy loss and energetic disorder of the OSCs. Furthermore, DBTF and DBOF have good volatility and can be removed from the active layer without any post-processing. Consequently, a high power conversion efficiency (PCE) of 18.78 % is obtained in D18: Y6-based OSCs and a remarkable PCE of 19.19 % is realized in D18-Cl/ Y6-based OSCs. Compared with the OSCs without or with conventional TBB additives, the DBOF-treated OSCs effectively suppress the reduction of VOC while enhancing PCE. This work provides guidance for the design and synthesis of additives with selectivity, auto-removability, and the ability to reduce the energetic disorder of the OSCs.

Investigation of cholinesterase and α-glucosidase enzyme activities, and molecular docking and dft studies for 1,2-disubstituted cyclopentane derivatives with phenyl and benzyl units.

Six known products (4-9) were prepared from reaction of adipoyl chloride with 1,2,3-trimethoxybenzene according to the literature. From (2,3,4-trimethoxyphenyl)(2-(2,3,4-trimethoxyphenyl)cyclopent-1-en-1-yl)methanone (4) of them, four new 1,2-disubstituted cyclopentane derivatives (10-13) with phenyl and benzyl units were synthesized by reactions such as hydrazonation, catalytic hydrogenation and bromination. The obtained compounds 4-13 were examined for their in vitro inhibitory activity against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glucosidase enzymes. All compounds 4-13 showed inhibition at nanomolar level with Ki values in the range of 45.53 ± 7.35-631.96 ± 18.88nM for AChE, 84.30 ± 9.92-622.10 ± 35.14nM for BChE, and 25.47 ± 4.46-48.87 ± 7.33 for α-Glu. In silico molecular docking studies of the potent compounds were performed in the active sites of AChE (PDB: 1E66), BChE (PDB: 1P0I), and α-glucosidase (PDB: 5ZCC) to compare the effect of bromine atom on the inhibition mechanism. The optimized molecular structures, HOMO-LUMO energies and molecular electrostatic potential maps for the compounds were calculated by using density functional theory with B3LYP/6-31 + G(d,p).

Exploring novel bromo heterocyclic scaffold and theoretical explanation of their biological actions

In this elucidation, we synthesized different heterocyclic compounds through (E)-1-(2‑bromo-4-methylphenyl)-3-(4-bromophenyl)prop‑2-en-1-one(3) which is synthesized from the aldol condensation between 4-bromobenzaldehyde and 1-(2‑bromo-4-methylphenyl)ethan-1-one in the basic condition in excellent yield. Furthermore, the chalcone 3 showed also varied activity with nitrogen nucleophiles and active methylene and displayed different heterocyclic rings which were confirmed through different spectral analyses such as FT-IR, 1HNMR, 13CNMR, and mass spectrum. Moreover, the synthesized heterocyclic exhibited antimicrobial properties against various microbial strains (Gram-positive, Gram-negative, and fungal strains) through the well diffusion methodology and comparable with Ampicillin and Mycostatin drugs. Furthermore, the synthesized compounds demonstrated various radical scavenger properties and antioxidant activities. These biological analyses demonstrated various binding energies and interactions with proteins and were validated through molecular docking studies using distinct protein pockets interaction. Additionally, the Frontier Molecular Orbitals (FMO), which are physical descriptors of optimal structures that are connected with biological evaluations and demonstrate the activities of these compounds due to presence of two bromine atom which effect on electron deficiency and increase its action which examined via the DFT/B3LYP/6-311G basis set.

Site‐Selective Distal C(sp3)−H Bromination of Aliphatic Amines as a Gateway for Forging Nitrogen‐Containing sp3 Architectures

AbstractHerein, we disclose a new strategy that rapidly and reliably incorporates bromine atoms at distal, secondary C(sp3)−H sites in aliphatic amines with an excellent and predictable site‐selectivity pattern. The resulting halogenated building blocks serve as versatile linchpins to enable a series of carbon‐carbon and carbon‐heteroatom bond‐formations at remote C(sp3) sites, thus offering a new modular and unified platform that expediates the access to advanced sp3 architectures possessing valuable nitrogen‐containing saturated heterocycles of interest in medicinal chemistry settings.