Br Interactions Research Articles

Room‐Temperature Wide‐Gap Inorganic Materials with Excellent Plasticity

AbstractIn general, inorganic non‐metallic materials exhibit brittleness, and achieving plasticity in wide‐gap semiconductors or dielectrics poses an even greater challenge. Historically, silver halides have been suggested to be ductile; however, their deformability under different load modes has not been well demonstrated, and the underlying mechanisms are not fully understood. In this study, the authors demonstrate the excellent plasticity of AgCl and AgBr polycrystals at room temperature under tension, bending, compression, and roller pressing. In particular, the rolling reduction rate of AgCl/AgBr exceeds 97%, corresponding to the plastic extensibility from 3600% to 4200%. The metal‐like plasticity and multiple slip systems are attributed to the ionic features, specifically the Coulombic nature of the Ag‐Cl/Br interactions, and the appreciable polarization of the anions. Such less localized diffuse bonding can be readily switched upon atomic gliding, thus ensuring slip without cleavage. This study contributes to the advancement of the understanding and development of wide‐gap plastically deformable inorganic materials for applications in flexible, shape‐conformable high‐power electronics and dielectrics.

N-Cyclo-hexyl-tryptamine: freebase, bromide and fumarate.

The solid-state structures of N-cyclo-hexyl-tryptamine (I) {systematic name: N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-namine}, C16H22N2, and two of its salts, N-cyclo-hexyl-tryptammonium bromide (II) {systematic name: N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-naminium bromide}, C16H23N2 +·Br-, and N-cyclo-hexyl-tryptammonium fumarate (III) (systematic name: bis-{N-[2-(1H-indol-3-yl)eth-yl]cyclo-hexa-naminium} (2E)-but-2-enedioate), 2C16H23N2 +·C4H2O4 2-, were determined by single-crystal X-ray diffraction. The freebase compound forms infinite chains along [010] through N-H⋯N hydrogen bonds. The bromide salt is held together by N-H⋯Br inter-actions in two-dimensional sheets along (001). The fumarate salt is held together in infinite three-dimensional frameworks by N-H⋯O hydrogen bonds.

H/Br substitution in ethylamine improves the phase transition temperature of in-based material (BrC2H4NH3)3[InBr6

Organic-inorganic hybrid phase transition materials with simple synthesis and flexible structure have become a research hotspot. However, one of the obstacles for expanding their application prospects is how to effectively adjust the phase transition temperature. Herein, taking advantage of H/Br substitution on the reported In-based phase transition material (C2H5NH3)3[InBr6], a new In-based material (BrC2H4NH3)3[InBr6] (1) was successfully prepared (Tc = 288 K). As expected, the Tc is successfully improved from 248 K of (C2H5NH3)3[InBr6] to 288 K of (BrC2H4NH3)3[InBr6], effectively regulating the phase transition temperature. The variable-temperature structure elucidation suggests that the disorder degree transitions of (BrC2H4NH3)+ cations triggers the phase transition. The introduction of heavier atom (Br) and Br···Br interaction increases the rotational energy barrier of the (BrC2H4NH3)+ cation, which leads to the enhancement of the phase transition temperature. In addition, compound 1 shows dielectric anomalies near Tc, which is consistent with DSC result. This work provides an effective method for further expanding the application range of phase transition materials.

Structural studies of Schiff base ligand and its copper complexes: Solvents effect in 1-D polymeric and monomeric copper (II) complexes, computational and sensing studies

The Schiff base ligand (E)-2,4-dibromo-6-(((2-(methylthio)phenyl)imino)methyl)phenol (SL5) and their copper complexes were synthesized. The complex-1 ([Cu (SL5) (CH3COO)]n) and complex-2 ([Cu (SL5) (CH3COO) (CH3OH)]) were obtained by inducing acetic and methanol solvent by post-synthetic modification. Both ligand and metal complexes were characterized by FTIR, SEM, and EDAX analysis. In addition, the photoluminescence behaviour has also been studied. The crystal structures of both ligand and metal complexes were determined by single-crystal X-ray diffraction studies. The structure was solved by direct methods using the SHELXS program and refined by the SHELXL program. The structural changes of ligand in the formation of the metal complexes and the solvent-induced effect of acetic acid and methanol on copper complexes have been studied using crystal structure analysis. The SL5 ligand and complex-2 crystallize in the Monoclinic, P21/n space group and complex-1 crystallize in the Tetragonal, I41/a space group. Complex-1 exhibits six coordinated distorted octahedral geometry. The addition of methanol solvent to complex-1 forms complex-2 and has five coordinated square pyramidal geometry. Complex-1 forms a 1-D coordination polymer chain via Cu1–O3 and it is replaced by the O2–H2‧‧‧O4 interaction with the aid of coordinated methanol solvent in complex-2. The effect of solvents on the coordination sphere directly influences the chelating rings. Complexes-1 exhibits interesting type-II halogen‧‧‧halogen (Br‧‧‧Br) interaction, leading to the formation of tetramer synthons (X4). Halogen-halogen interactions are broken down by adding a methanol solvent, resulting in halogen-hydrogen interactions in complex-2. Crystal structure and quantum computational studies have analyzed the synergetic effect of ligand and solvents on the molecular packing of metal complexes. The Cu(OAc)2SL5 receptor selectively detects sulfide anion in aqueous acetonitrile HEPES buffer solution in the presence of other anions. Further, antibacterial activity has been carried out for MRSA bacteria, and docking studies were carried out for penicillin-binding protein to explore the effect of coordination and solvents.

Structure property relationship in two thiazole derivatives: Insights of crystal structure, Hirshfeld surface, DFT, QTAIM, NBO and molecular docking studies

Detailed structural and noncovalent interactions in two thiazole derivatives (N-(4-Bromophenyl)-2-(methylthio)thiazole-5-carboxamide and Ethyl-5-((4-bromophenyl)carbamoyl)thiazole-4-carboxylate) are investigated by single crystal X-ray diffraction study and computational approaches. The structure investigation revealed that various interactions like C-H…O, N-H…O, and N-H…N hydrogen bonds and Br…Br interactions are involved in constructing ring motifs to stabilize the crystal packing. Hirshfeld surface analysis and fingerprint plots were carried out to study the differences and similarities in the relative contribution of noncovalent interactions in both the molecules. The FMOs and other global reactive parameters are analyzed for thiazole derivatives. The strength and nature of weak interactions present in the molecule were characterized by RDG-based NCI and QTAIM analyses. Natural bond orbital (NBO) analysis unravels the importance of non-covalent and hyperconjugative interactions for the stability of the molecules in their solid state. Further, molecular docking of N-(4-Bromophenyl)-2-(methylthio)thiazole-5-carboxamide and Ethyl-5-((4-bromophenyl)carbamoyl)thiazole-4-carboxylate with SARS-Covid-19 have been carried out.

A family of methoxide-bridged Cu(II) compounds with N-heterocyclic ligands: dimers and chains

Three new methoxide-bridged Cu(II) dimers are reported: tetrakis(2-methylpyrazine)di(μ-methoxy)diperchloratodicopper(II) (1), tetrakis(2-amino-5-iodopyridine)dibromide-di-μ-methoxydicopper(II) tetramethanol (2) and catena[(2-amino-5-methylpyridine)μ-bromido-μ-methoxycopper(II) (3). The compounds were characterized by single-crystal X-ray diffraction and variable temperature magnetic measurements. All three compounds crystallize in the triclinic space group P-1, and the dimers lie across a crystallographic inversion center. The dimers in 3 are further bridged into an alternating chain motif via semi-coordinated Cu(II)/Br interactions. All three compounds exhibit strong antiferromagnetic interactions with J/kB = −348(8) K for 1, and the exchange in 2 and 3 being too strong to estimate from the available data. The magnetic data for 1-3 are dominated by trace paramagnetic impurities at temperatures below 200 K. Correlation of the structures with the observed magnetic behavior is proposed.

Dibromomethyl- and bromomethyl- or bromo-substituted benzenes and naphthalenes: C-Br...Br interactions.

The structures of six benzene and three naphthalene derivatives involving bromo, bromomethyl and dibromomethyl substituents, namely, 1,3-dibromo-5-(dibromomethyl)benzene, C7H4Br4, 1,4-dibromo-2,5-bis(bromomethyl)benzene, C8H4Br6, 1,4-dibromo-2-(dibromomethyl)benzene, C7H4Br4, 1,2-bis(dibromomethyl)benzene, C8H6Br4, 1-(bromomethyl)-2-(dibromomethyl)benzene, C8H7Br3, 2-(bromomethyl)-3-(dibromomethyl)naphthalene, C12H9Br3, 2,3-bis(dibromomethyl)naphthalene, C12H8Br4, 1-(bromomethyl)-2-(dibromomethyl)naphthalene, C12H9Br3, and 1,3-bis(dibromomethyl)benzene, C8H6Br4, are presented. The packing patterns of these compounds are dominated by Br...Br contacts and C-H...Br hydrogen bonds. The Br...Br contacts, shorter than twice the van der Waals radius of bromine (3.7 Å), seem to play a crucial role in the crystal packing of all these compounds. The occurrence of Type I and Type II interactions is also discussed briefly, considering the effective atomic radius of bromine, as is their impact on the packing of molecules in the individual structures.

Boat and Chair Shaped Hexahalogen Synthons.

Non-covalent halogen bonding interactions are quintessential in crystal engineering for the construction of distinctive supramolecular synthons. Here, we report the first crystalline evidences of unique boat and chair shaped cyclic hexahalogen synthons in the crystal structures of α,α,α',α',4-pentabromo-o-xylene (PBX) and α,α,α',α',4,5-hexabromo-o-xylene (HBX) respectively. Nature and stability of constituent interactions in the supramolecular synthons are scrutinized with the help of quantum-chemical calculations. Pendás' interacting quantum atoms approach confirmed the stability of Br⋅⋅⋅Br interactions leading to boat and chair shaped synthons with major contribution from exchange-correlation. Although both the molecules are achiral in nature, the packing forces guide PBX to crystallize in the chiral space group P21 with a helix-like orientation while HBX packs in a centrosymmetric P21 /n space group. The extended furcations in the pentabromo derivative construct a molecular framework consisting of macrocycles realized through halogen bonding.

Two-photon absorption of FAPbBr3 perovskite nanocrystals

Perovskite nanocrystals (NCs) with high two-photon absorption (TPA) cross-section are of great interest due to their potential applications in three-dimensional optical data storage and multiphoton fluorescence microscopy. Among various perovskite materials, FAPbBr3 NCs show a better development prospect due to their excellent stability. However, there are few reports on their nonlinear optical properties. In this work, the nonlinear optical behavior of FAPbBr3 NCs is studied. The methods of multiphoton absorption photoluminescence saturation and open aperture Z-scan technique were applied to determine the TPA cross-section of FAPbBr3 NCs, which was around 2.76 × 10−45 cm4⋅s⋅photon−1 at 800 nm. In addition, temperature-dependent photoluminescence induced by TPA was investigated, and the small longitudinal optical phonon energy and electron–phonon coupling strength was obtained, which confirm the weak Pb–Br interaction. Meanwhile, it is found that the exciton binding energy in FAPbBr3 NCs was 69.668 meV, which may be ascribed to the strong hydrogen bond interaction. It is expected that our findings will promote the application of FAPbBr3 NCs in optoelectronic devices.

Spectroscopic and structural characterization of hexaamminecobalt(III) dibromide permanganate

Structural and spectroscopic characterization (SXRD, IR, liq. N2 temperature Raman, UV) of hexaamminecobalt(III) dibromide permanganate, [Co(NH3)6]Br2(MnO4) (compound 1), are described. There is a 3D hydrogen bond network including N?H???O?Mn and N?H???Br interactions, which could serve as potential reaction centres for solid-phase redox reactions between the ammonia ligands and/or bromide ions as reductants and permanganate ions as oxidant agents. The effect of the nature of halogen ions on the structural and spectroscopic properties of [Co(NH3)6]Br2(MnO4) and the analogous chloride compound, [Co(NH3)6]Cl2(MnO4) (compound 2), are discussed in detail.

Model for self-assembly of Br–H and Br–Br bonded Br4Py molecules

A model, based on the pairwise intermolecular halogen–hydrogen (Br–H) and halogen–halogen (Br–Br) bonding, is proposed to describe the self-assembly of Br4Py molecules into two different planar structures (Phase I and Phase II). The pair bonding interactions are calculated by the density functional theory for the two-molecule and four-molecule clusters. It is shown that about 60% of bonding strength is due to the electrostatic Br(top)–Br(belt) interactions, while the remaining originates from Br–H interactions. The obtained values of pair interactions are further used for Monte Carlo calculations. The model for these calculations is proposed on a square lattice. The two main pair interactions are needed for the emergence of the Phase I ordering, while the Phase II ordering is obtained using a single interaction. The obtained results explain the emergence of both phases.

Predicting Blood-Brain Barrier Permeation of Erlotinib and JCN037 by Molecular Simulation.

Glioblastoma (GBM) is a highly malignant primary brain tumor, and epidermal growth factor receptor (EGFR) is a well characterized biomaker on GBM. Treatment of GBM with EGFR inhibitors achieved limited efficacy due to low blood-brain barrier (BBB) permeability, and BBB-penetrant drugs are required.In this study, the BBB penetration of erlotinib and JN037 were studied using molecular dynamics method with explicit membrane model. The free energy profiles indicate that JCN037 has a lower central energy barrier than erlotinib, and it has a local minimum at lipid-water interface while erlotinib has not. Unconstrained MD simulations found that erlotinib prefers staying in water while JCN037 tends to interact with lipid molecules. Further analysis reveals that the Br atom of JCN037 plays an important role in its interaction with lipid molecules, and the adjacent F atom enhances the interaction of Br. The two flexible methoxyethoxy chains of erlotinib are responsible for its poor penetration. Our computational results agree well with the experimental results, providing useful information in the design and improvement of drugs with good BBB permeation.

Synthesis, crystal structure and Hirshfeld analysis of triphenylphosphine–(4-bromophenyl)borane

The title compound, alternatively called (4-bromophenyl)dihydrido(triphenylphosphanyl)boron, C24H21BBrP, crystallizes in the space group P-1 with one symmetry-independent molecule in the asymmetric unit. The B and P atoms both adopt the expected tetrahedral geometry. A possible intramolecular B-Hδ-...δ+H-C dihydrogen bond exists between an arene group on phosphorus and the borane center. In the solid state, the title molecule is connected to its neighbors by intermolecular C-H...π interactions, with the arene rings on the P atom acting as hydrogen-bond donors and the arene ring of the borane acting as the acceptor. Hirshfeld analysis supports the existence of these interactions, as well as weak Br...Br interactions between neighboring molecules.

Co(NCS)2 Chain Compound with Alternating 5- and 6-Fold Coordination: Influence of Metal Coordination on the Magnetic Properties.

The reaction of Co(NCS)2 with 3-bromopyridine leads to the formation of discrete complexes [Co(NCS)2(3-bromopyridine)4] (1), [Co(NCS)2(3-bromopyridine)2(H2O)2] (2), and [Co(NCS)2(3-bromopyridine)2(MeOH)2] (3) depending on the solvent. Thermogravimetric measurements on 2 and 3 show a transformation into [Co(NCS)2(3-bromopyridine)2]n (4), which upon further heating is converted to [{Co(NCS)2}2(3-bromopyridine)3]n (5), whereas 1 transforms directly into 5 upon heating. Compound 5 can also be obtained from solution, which is not possible for 4. In 4 and 5, the cobalt(II) cations are linked by pairs of μ-1,3-bridging thiocyanate anions into chains. In compound 4, all cobalt(II) cations are octahedrally coordinated (OC-6), as is usually observed in such compounds, whereas in 5, a previously unkown alternating 5- and 6-fold coordination is observed, leading to vacant octahedral (vOC-5) and octahedral (OC-6) environments, respectively. In contrast to 4, the chains in 5 are very efficiently packed and linked by π···π stacking of the pyridine rings and interchain Co···Br interactions, which is the basis for the formation of this unusual chain. The spin chains in 4 demonstrate ferromagnetic intrachain exchange and much weaker interchain interactions, as is usually observed for such linear chain compounds. In contrast, compound 5 shows almost single-ion-like magnetic susceptibility, but the magnetic ordering temperature deduced from specific heat measurements is twice as high as that in 4, which might originate from π···π stacking and Co···Br interactions between neighboring chains. More importantly, unlike all linear Co(NCS)2 chain compounds, a dominant antiferromagnetic exchange is observed for 5, which is explained by density functional theory calculations predicting an alternating ferro- and aniferromagnetic exchange within the chains. Theoretical calculations on the two different cobalt(II) ions present in 5 predict an easy-axis anisotropy that is much stronger for the octahedral cobalt(II) ion than for the one with the vacant octahedral coordination, with the magnetic axes of the two ions being canted by an angle of 84°. This almost orthogonal orientation of the easy axis of magnetization for the two cobalt(II) ions is the rationale for the observed non-Ising behavior of 5.

Non-Covalent Interactions in the Crystal Structures of Perbrominated Sulfonium Derivatives of the closo-Decaborate Anion.

A new series of compounds based on perbrominated disubstituted sulfonium derivatives of the closo-decaborate anion (n-Bu4N)[2-B10Br9SR2] (R = n-Pr, i-Pr, n-Bu, n-C8H17, n-C12H25, n-C18H37) was obtained, characterised by modern physicochemical methods of analysis. According to the results of an X-ray diffraction study, some of the anions and solvate molecules were disordered. The cations (n-Bu4N)+ and anions [2-B10Br9SR2]− were associated via C-H…Br and H…H contacts. In addition, Br…Br interactions between anions were revealed. The role of these contacts was analysed in terms of Hirshfeld surface analysis, QTAIM theory and the NCI method using quantum chemical calculations. An increase in the size of the alkyl R moiety led to significant strengthening of the total energy of H…H interactions. In the case of R = -n-C18H37, a parallel mutual orientation of alkyl moieties was established that was similar to the packing of salts of fatty acids. The nature of C-H…Br and Br…Br interionic interactions was found to be attractive, in contrast to the repulsive nature of intermolecular Br…Br interactions.

High efficient room temperature phosphorescent materials constructed with methylene molecular configuration.

In this work, we have investigated several pure organic room temperature phosphorescent materials with donor-methylene acceptor configurations with relatively different quantum efficiency. The results show that the introduction of methylene functional group in room temperature phosphorescent materials based on donor-acceptor configuration is more favorable for obtaining higher phosphorescent quantum efficiency in crystal phase environment. More importantly, our calculations reveal the root cause of the excellent quantum efficiency performance after the introduction of methylene groups. The results show that the introduction of methylene can inhibit the structural deformation of molecules during the excited state transition process and give them higher interaction. Moreover, in the donor-acceptor configuration, the heavy atom effect is more favorable to the formation of π-x (X = Br) interaction to accelerate the occurrence of intersystem crossing and achieve a higher intersystem crossing rate. Therefore, the donor-methylene-acceptor molecule is expected to improve the quantum efficiency of room temperature phosphorescence, and the addition of heavy atoms is more conducive to prolong the life of room temperature phosphorescence. This work provides a useful reference for rational design of room temperature phosphorescent materials with high efficiency and long life.

Intra- and Inter-Self-Assembly of Identical Supramolecules on Silver Surfaces

Self-assembly of identical organometallic supramolecules into ordered superstructures is of great interest in both chemical science and nanotechnology due to its potential to generate neoteric properties through collective effects. In this work, we demonstrate that large-scale self-organization of atomically precise organometallic supramolecules can be achieved through cascaded on-surface chemical reactions, by the combination of intra- and inter-supramolecular interactions. Supramolecules with defined size and shape are first built through intramolecular reaction and intermolecular metal coordination, followed by the formation of well-ordered two-dimensional arrays with the assistance of Br atoms by -C-H···Br interactions. The mechanism of this process has been investigated from the perspectives of thermodynamics and kinetics.

Crystal structure, Hirshfeld surface analysis and DFT calculations of 7-bromo-2,3-di-hydro-pyrrolo[2,1-b]quinazolin-9(1H)-one.

The mol-ecular structure of the title compound, C11H9BrN2O, is almost planar. The benzene and pyrimidine rings are essentially coplanar, with r.m.s. deviations of 0.0130 Å, and the largest displacement is for the flap atom of the di-hydro-pyrrole moiety [0.154 (7) Å]. Hirshfeld surface analyses revealed that the crystal packing is dominated by H⋯H, Br⋯H/H⋯Br and O⋯H/H⋯O inter-actions, and Br⋯Br inter-actions in the crystal structure are also observed. Theoretical calculations using density functional theory (DFT) with the B3LYP functional basis set gave numerical parameters for the frontier molecular orbitals.

Structural Diversity of Mercury(II) Halide Complexes Containing Bis-pyridyl-bis-amide with Bulky and Angular Backbones: Ligand Effect and Metal Sensing.

Hg(II) halide complexes [HgCl2] 2L1 [L1 = N,N’-bis(3-pyridyl)bicyclo(2,2,2,)oct-7-ene-2,3,5,6-tetracarboxylic diamide), 1, [HgBr2(L1)]n, 2, [HgI2(L1)], 3, [Hg2X4(L2)2] [X = Cl, 4, Br, 5, and I, 6; L2 = N,N’-bis(4-pyridylmethyl)bicyclo(2,2,2,)oct-7-ene-2,3,5,6-tetracarboxylic diamide] and {[HgX2(L3)]⋅H2O}n [X = Cl, 7, Br, 8 and I, 9; L3 = 4,4′-oxybis(N-(pyridine-3-yl)benzamide)] are reported and structurally characterized using single-crystal X-ray diffraction analyses. The linear HgCl2 units of complex 1 are interlinked by the L1 ligands through Hg---N and Hg---O interactions, resulting in 1D supramolecular chains. Complex 2 shows 1D zigzag chains interlinked through the Br---Br interactions to form 1D looped supramolecular chains, while the mononuclear [HgI2L2] molecules of 3 are interlinked through Hg---O and I---I interactions, forming 2D supramolecular layers. Complexes 4–6 are isomorphous dinuclear metallocycles, and 7–9 form isomorphous 1D zigzag chains. The roles of the ligand type and the halide anion in determining the structural diversity of 1–9 is discussed and the luminescent properties of 7–9 evaluated. Complexes 7–9 manifest stability in aqueous environments. Moreover, complexes 7 and 8 show good sensing towards Fe3+ ions with low detection limits and good reusability up to five cycles, revealing that the Hg-X---Fe3+ (X = Cl and Br) interaction may have an important role in determining the quenching effect of 7 and 8.

Crystal structure and Hirshfeld surface analysis of a new polymorph of (E)-2-(4-bromo-phen-yl)-1-[2,2-di-bromo-1-(3-nitro-phen-yl)ethen-yl]diazene.

A new polymorph of the title compound, C14H8Br3N3O2, (form-2) was obtained in the same manner as the previously reported form-1 [Akkurt et al. (2022 ▸). Acta Cryst. E78, 732-736]. The structure of the new polymorph is stabilized by a C-H⋯O hydrogen bond that links mol-ecules into chains. These chains are linked by face-to-face π-π stacking inter-actions, resulting in a layered structure. Short inter-mol-ecular Br⋯O contacts and van der Waals inter-actions between the layers aid in the cohesion of the crystal packing. In the previously reported form-1, C-H⋯Br inter-actions connect mol-ecules into zigzag chains, which are linked by C-Br⋯π inter-actions into layers, whereas the van der Waals inter-actions between the layers stabilize the crystal packing of form-2. Hirshfeld mol-ecular surface analysis was used to compare the inter-molecular inter-actions of the polymorphs.