Biphenyl Molecule Research Articles

MD simulations of diffusion of cyanobiphenyl molecules adsorbed on the graphene surface coated with alkane and alcohol molecules

AbstractMolecular dynamics simulations were carried out to study the structural and diffusion properties of a cyanobiphenyl monolayer composed of pentyl cyano biphenyl (5CB) and pentyloxy cyano biphenyl (5OCB) molecules on a graphene surface coated with alkane and alcohol molecules. To investigate the diffusion properties of 5CB and 5OCB molecules on the graphene surface, the molecules of pentane ( ) and dodecane ( ) from alkanes and dodecanol ( ) from alcohols with a polar hydroxyl ( ) terminal functional group were chosen as orienting surfactant molecules. It was found that the diffusion ability of cyanobiphenyl molecules in a graphene substrate coated with alkane and alcohol molecules depends on the chain length of these molecules and on the presence of polar hydroxyl –OH terminal groups. With an increase in the length of alkane molecules from to , the value of the diffusion coefficient (or ), it decreases slightly, while the presence of the polar hydroxyl terminal group leads to a significant decrease in this diffusion coefficient of cyanobiphenyl molecules.

Structural properties of a cyanobiphenyl monolayer on the graphene surface coated with alkane and alcohol molecules as seen from MD simulations

Molecular dynamics simulations were carried out to study structural properties of a cyanobiphenyl monolayer composed of pentyl cyano biphenyl (5CB) and pentyloxy cyano biphenyl (5OCB) molecules on a graphene surface coated with alkane and alcohol molecules. The molecules of dodecane, hexadecane, and dodecanol were chosen as orienting surfactant molecules. In order to investigate the structural properties, as well as the alignment of the cyanobiphenyl monolayer on the graphene surface coated with alkane and alcohol molecules, not only the numerical density profiles of these systems, but also the radial distribution functions, and the tilt angle of the liquid crystal molecules, were calculated. In order to understand the effect of the polar hydroxyl functional group on 5CB and 5OCB molecules deposited on the graphene surface, alcohols were chosen as surfactant molecules.

Solvation‐Driven Grain Boundary Passivation Improving the Performance of Perovskite Solar Cells

AbstractThe efficiency of perovskite solar cells (PSCs) is hindered by substantial defects within the grain boundaries (GBs) of polycrystalline perovskite films. Conventional post‐treatment strategies struggle to precisely repair these defects at GBs. Here, a targeted grain boundary passivation strategy through solvent effects by incorporating symmetrical biphenyl molecules is proposed, 4,4′‐diaminodiphenyl sulfone (DDS) and 4,4′‐sulfodiphenol (SDP), aiming to mitigate defects at GBs and optimize energy level arrangements through their electric dipole effects. Compared to the pristine device, the SDP‐modified device exhibits significant improvements, including a champion efficiency of 24.39% and an impressive fill factor, along with excellent operation stability. This work provides an effective and straightforward solution for improving the performance of PSCs.

Unconventional gas-phase synthesis of biphenyl and its atropisomeric methyl-substituted derivatives.

The biphenyl molecule (C12H10) acts as a fundamental molecular backbone in the stereoselective synthesis of organic materials due to its inherent twist angle causing atropisomerism in substituted derivatives and in molecular mass growth processes in circumstellar environments and combustion systems. Here, we reveal an unconventional low-temperature phenylethynyl addition-cyclization-aromatization mechanism for the gas-phase preparation of biphenyl (C12H10) along with ortho-, meta-, and para-substituted methylbiphenyl (C13H12) derivatives through crossed molecular beams and computational studies providing compelling evidence on their formation via bimolecular gas-phase reactions of phenylethynyl radicals (C6H5CC, X2A1) with 1,3-butadiene-d6 (C4D6), isoprene (CH2C(CH3)CHCH2), and 1,3-pentadiene (CH2CHCHCHCH3). The dynamics involve de-facto barrierless phenylethynyl radical additions via submerged barriers followed by facile cyclization and hydrogen shift prior to hydrogen atom emission and aromatization to racemic mixtures (ortho, meta) of biphenyls in overall exoergic reactions. These findings not only challenge our current perception of biphenyls as high temperature markers in combustion systems and astrophysical environments, but also identify biphenyls as fundamental building blocks of complex polycyclic aromatic hydrocarbons (PAHs) such as coronene (C24H12) eventually leading to carbonaceous nanoparticles (soot, grains) in combustion systems and in deep space thus affording critical insight into the low-temperature hydrocarbon chemistry in our universe.

Multifunctional spin transport behaviors of biphenyl-molecule-based nanodevices

For the development of low-power spin-multifunctional devices, we have explored the spin-dependent transport properties of nanodevices based on zigzag graphene nanoribbons bridged respectively by oblique, horizontal, and vertical connecting biphenyl molecules. Utilizing the first-principles calculations associated with the non-equilibrium Green's function methods, we found the superb transport results demonstrate that almost 100% spin polarization exists for the obliquely connected and horizontally connected biphenyl molecules devices in the parallel state (P). All of the designed devices exhibit excellent dual spin filtering efficiency and rectification effect in the antiparallel state (AP) with the rectification ratios up to 103, 104, and 105 for obliquely, horizontally, and vertically connected model devices, respectively. Simultaneously, a pronounced negative differential resistance effect can be observed in these devices independent of the spin state. Moreover, the thermal spin transport properties of the obliquely connected model device reveal an apparent Seebeck effect. Then, the length effect on the spin-resolved transport properties for the obliquely connected device have been conducted. Results reveal that the current values are highly tunable by changing the length of obliquely connected biphenyl molecules in the P state. Meanwhile, the doual spin filtering effect still remains, but its rectification effect gradually disappears with the increasing length of center scattering region in AP state. This study provides new insights into the design of multifunctional spin carbon-based and low power consumption devices.

Theoretical survey on the electronic, linear and nonlinear optical properties of substituted benzenes and polycondensed π-systems. A density functional theory study

Herein dipole moments, static and dynamic (hyper)polarizabilities, delocalization energies, distortions of the phenyl rings of the substituted benzenes are computed using density functional theory procedure. It is revealed that the biphenyl molecule exhibits the largest frequency-dependent second order hyperpolarizabilities. Furthermore, the application of an external electric field along the direction parallel to the molecular plane induces a considerable decrease in the energy of the unoccupied orbitals of biphenyl, resulting in more red-shifted virtual orbitals compared with benzene and the highest static second-order hyperpolarizability for the molecule. It is also found that when the two adjacent rings share only one carbon atom, high σ and π-electronic contributions to the second-order hyperpolarizabilities are expected. Interactions of the type π* → π* with high delocalization energies are predicted for pyridine, nitrobenzene, chlorobenzene, bromobenzene, phenol, and benzoic acid. The quantum–mechanical calculations of the present work may provide theoretical insights into designing high (hyper)polarizability materials.

Cold Oxidative Demetalation of Aryl Organometallics: A Novel Route to Demetalate Ullmann Intermediates without Heating

AbstractA new way of demetalating Ullmann organometallic aryl intermediates is proposed that uses charging rather than heating conditions. Ab initio molecular dynamics simulations show that certain aryl organosilver and organocopper intermediates (MPh2, with M=Cu, Ag and Ph=phenyl group) spontaneously demetalate even starting with zero velocities upon the oxidative removal of one electron. The oxidative demetalation is driven by the loss of electron density in the interatomic C−M region and leads to a biphenyl molecule with a η‐coordinated nearby M atom. The main advantage of this dry redox demetalation process is that it avoids the use of high temperatures which have deleterious effects on the yields. The method does not compromise the thermal stability of the end product and reduces the chances of uncontrolled side reactions. The demetalation of oxidized MPh2 is predicted to occur spontaneously in the gas phase and on an inert surface. A possible experimental setup is proposed to test this idea in the widely‐used Ullmann reaction for the controlled on‐surface synthesis of new C−C bonds. The reduction‐induced planarization of the neutral MPh2 molecule is reversible and could be used as an electro‐mechanical nano‐switch. The neutral and anionic compounds are predicted to be locally aromatic and dynamically stable. For bimetallic aryl intermediates (M2Ph3), the irreversible demetalation occurs upon the removal of two electrons leading to the dication.

C-C Bond Formation Reaction Catalyzed by a Lithium Atom: Benzene-to-Biphenyl Coupling.

Transition-metal-catalyzed carbon-carbon (C-C) bond formation is an important reaction in pharmaceutical and organic chemistry. However, the reaction process is composed of multiple steps and is expensive owing to the presence of transition metals. This study proposes a lithium-catalyzed C-C coupling reaction of two benzene molecules (Bz) to form a biphenyl molecule, which is a transition-metal-free reaction, based on ab initio and direct ab initio molecular dynamics (AIMD) calculations. The static ab initio calculations indicate that the reaction of two Bz molecules with Li- ions (reactant state, RC) can form a stable sandwiched complex (precomplex), where the Li- ion is sandwiched by two Bz molecules. The complex formation reaction can be expressed as 2Bz + Li - → Bz(Li -)Bz, where the C-C distance between the Bz rings is 2.449 Å. This complex moves to the transition state (TS) via the structural deformation of Bz(Li-)Bz, where the C-C distance is shortened to 2.118 Å. The barrier height was calculated to be -9.9 kcal/mol (relative to RC) at the MP2/6-311++G(d,p) level. After TS, the C(sp3)-C(sp3) single bond was completely formed between the Bz rings (the C-C bond distance was 1.635 Å) (late complex). After the dissociation of H2 from the late complex, a biphenyl molecule was formed: the C(sp2)-C(sp2) bond. The calculations suggest that the C-C bond coupling of Bz occurred spontaneously from 2Bz + Li-, and biphenyl molecules were directly formed without an activation barrier. Direct AIMD calculations show that the C-C coupling reaction also takes place under electron attachment to Li(Bz)2: Li(Bz)2 + e- → [Li-(Bz)2]ver → precomplex → TS → late complex, where [Li-(Bz)2]ver is the vertical electron capture species of Li(Bz)2. Namely, the C-C coupling reaction spontaneously occurred in Li(Bz)2 owing to electron attachment. Similar C-C coupling reactions were also observed for halogen-substituted benzene molecules (Bz-X, X = F and Cl). Furthermore, this study discusses the mechanism of C-C bond formation in electron capture based on the theoretical results.

Asymmetric rotations and dimerization driven by normal to modulated phase transition in 4-biphenylcarboxy coupled L-phenylalaninate.

Amongst the derivatives of 4-biphenylcarboxylic acid and amino acid esters, the crystal structure of 4-biphenylcarboxy-(L)-phenylalaninate is unusual owing to its monoclinic symmetry within a pseudo-orthorhombic crystal system. The distortion is described by a disparate rotational property around the chiral centers (ϕchiral ≃ -129° and 58°) of the two molecules in the asymmetric unit. Each of these molecules comprises planar biphenyl moieties (ϕbiphenyl = 0°). Using temperature-dependent single-crystal X-ray diffraction experiments we show that the compound undergoes a phase transition below T ∼ 124 K that is characterized by a commensurate modulation wavevector, q = δ(101), δ = ½. The (3+1)-dimensional modulated structure at T = 100 K suggests that the phase transition drives the biphenyl moieties towards noncoplanar conformations with significant variation of internal torsion angle (ϕmaxbiphenyl ≤ 20°). These intramolecular rotations lead to dimerization of the molecular stacks that are described predominantly by distortions in intermolecular tilts (θmax ≤ 20°) and small variations in intermolecular distances (Δdmax ≃ 0.05 Å) between biphenyl molecules. Atypical of modulated structures and superstructures of biphenyl and other polyphenyls, the rotations of individual molecules are asymmetric (Δϕbiphenyl ≈ 5°) while ϕbiphenyl of one independent molecule is two to four times larger than the other. Crystal-chemical analysis and phase relations in superspace suggest multiple competing factors involving intramolecular steric factors, intermolecular H-C...C-H contacts and weak C-H...O hydrogen bonds that govern the distinctively unequal torsional properties of the molecules.

A fruitful century for the scalable synthesis and reactions of biphenyl derivatives: applications and biological aspects.

This review provides recent developments in the current status and latest synthetic methodologies of biphenyl derivatives. Furthermore, this review investigates detailed discussions of several metalated chemical reactions related to biphenyl scaffolds such as Wurtz-Fittig, Ullmann, Bennett-Turner, Negishi, Kumada, Stille, Suzuki-Miyaura, Friedel-Crafts, cyanation, amination, and various electrophilic substitution reactions supported by their mechanistic pathways. Furthermore, the preconditions required for the existence of axial chirality in biaryl compounds are discussed. Furthermore, atropisomerism as a type of axial chirality in biphenyl molecules is discussed. Additionally, this review covers a wide range of biological and medicinal applications of the synthesized compounds involving patented approaches in the last decade corresponding to investigating the crucial role of the biphenyl structures in APIs.

Полихлорированные бифенилы как причина экологических проблем и разработки ремедиационных технологий на основе биологических агентов

The review presents an analysis of currently pressing problems associated with environmental pollution by polychlorinated biphenyls – compounds included in the list of Persistent Organic Pollutants under the international con-vention. The structural features of the polychlorinated biphenyl molecule and their interaction with the environment and living organisms are shown. The main attention is paid to aerobic bacteria, one of the main components of soil microbi-ocenosis. It was shown that long-term exposure to polychlorinated biphenyls led to the preferential selection in contaminated microbiocenosis of bacteria capable of using polychlorinated biphenyls as a source of carbon and energy. The most active strains served as the basis for biotechnological preparations aimed at removing PCBs from the environment.

How are polychlorinated biphenyls currently being produced, despite the production ban, and do they pose a risk to the environment?

Abstract Polychlorinated biphenyls (PCBs) are a group consisting of 209 congeners, differing in the number and site of substitution of chlorine atoms to the biphenyl molecule. Due to their physicochemical properties, they have found wide industry use. As a result of many years of large-scale use of PCBs, their toxic properties began to be noticed as they manifested in poisoning among humans. After thorough testing of PCBs, they were classified in the group of persistent organic pollutants (POPs), and their production was banned and they were withdrawn from use. Although PCBs are no longer produced in factories, they can still be formed. In this article, will be presented and explained methods of accidental formation of PCBs. Based on data from the literature, we performed an environmental risk assessment for PCB-contaminated soils.

Effects of environmental factors on the fleroxacin photodegradation with the identification of reaction pathways

The abuse of fluoroquinolones (FQs) antibiotics leads to bacterial resistance and environmental pollution, so it is of great significance to verify the decomposition mechanism for eliminating antibiotic efficiently and conveniently. The effects of various environmental factors and the fleroxacin (FLE) photodegradation mechanisms were investigated by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS), UV–Vis absorption spectroscopy, fluorescence spectroscopy and quantum chemical calculation. Six possible photodegradation reaction paths on T1 (excited triplet state) were proposed and simulated. The departure of the piperazine ring and the substitution of F atom at C-6 position by OH group were determined as the main reactions based on the reaction rates and energy barriers of each path. The multi-pathway reactions resulted in the fastest photodegradation rates of FLE at pH 6–7 than other pH conditions. NaN3 would promote FLE photodegradation by inhibiting the reverse reaction of the separation process of F atom at C-8 and the generation of biphenyl molecules, which was a novel and distinctive phenomenon in this report. ·OH would rapidly combine with the free radicals generated in photolysis processes and made a great contribution to FLE photodegradation. Ca2+, Mg2+ and Ba2+ could stabilize the carboxyl group to impede the photo-competitive process of the decarboxylation reaction, while NO3− could generate reactive oxygen species to promote photodegradation.

Electronic transport properties of a single biphenyl molecule anchored on Au(111)with sulfur, selenium, and tellurium atoms.

Selenium and tellurium have recently been proposed as alternatives to sulfur anchoring groups for self-assembly of organic molecules on noble-metal substrates. Here, we conduct quantum transport calculations for a single biphenyl molecule anchored on Au (111) electrodes with thiolate, selenolate, and telluride terminal groups taking into account both dispersive interactions and spin-orbit coupling. The numerical results show that the current through the junction decreases by increasing the atomic number of the chalcogen atom due to nanoscale charge localization as revealed in transmission eigenstates analysis. The effect of spin-orbit coupling becomes more pronounced by increasing the atomic number of the chalcogen atom. Clear current rectification is obtained when the molecule is asymmetrically connected to the electrodes using different chalcogen atoms. These findings can be useful in exploring transport properties of organic molecules adsorbed on metallic surfaces using alternatives to sulfur chalcogen atoms.

Laser-Induced Coulomb Explosion Imaging of Aligned Molecules and Molecular Dimers.

We discuss how Coulomb explosion imaging (CEI), triggered by intense femtosecond laser pulses and combined with laser-induced alignment and covariance analysis of the angular distributions of the recoiling fragment ions, provides new opportunities for imaging the structures of molecules and molecular complexes. First, focusing on gas phase molecules, we show how the periodic torsional motion of halogenated biphenyl molecules can be measured in real time by timed CEI, and how CEI of one-dimensionally aligned difluoroiodobenzene molecules can uniquely identify four structural isomers. Next, focusing on molecular complexes formed inside He nano-droplets, we show that the conformations of noncovalently bound dimers or trimers, aligned in one or three dimensions, can be determined by CEI. Results presented for homodimers of CS2, OCS, and bromobenzene pave the way for femtosecond time-resolved structure imaging of molecules undergoing bimolecular interactions and ultimately chemical reactions.

Adsorption and reaction of an alkyne molecule on diverse oxygen-reconstructed Cu(110) surfaces

Studying the adsorption and reaction behaviors of organic molecules on solid surfaces holds great significance for producing high-performance organic films. Alkynes recently gain increasing popularity in on-surface self-assembly and reaction due to the peculiar nature of alkynyl groups. Here, we deposited 4-ethynyl-1,1′-biphenyl molecules (EBPs) on various oxygen-reconstructed Cu(110) surfaces derived from controllable oxidations. Both the structures of reconstructed surfaces and the adsorption/reaction properties of EBPs were investigated by scanning tunneling microscopy (STM), complemented with low energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SRPES). It is revealed that on the striped Cu-O nanotemplate surface, dehydrogenated EBPs prefer to decorate Cu region and form V-shaped dimers in large proportion. At the Cu/Cu-O interface, EBPs are aligned with their long axis along the Cu-O chain growth direction. Annealing to elevated temperatures merely induces intermolecular reactions among a few monomers. On the complete Cu(110)-(2 × 1)O surface, intact EBPs self-assemble into ordered and well-defined islands, where EBPs are confined by channels between Cu-O chains. On Cu(110)-c(6 × 2)O structure, non-covalent EBP dimers are dominant species. The orientation of these dimers is found to be dictated by corrugation between super Cu atom rows. Moreover, a Cu(110)-p(2 × 3)O surface is attained for the first time in this work, which, however, hardly anchor EBPs. In general, this work serves a model system for the research on adsorption and reaction of alkyne molecules on metal oxide surfaces.

Adsorption dynamics and intrinsic mechanism of POPs on corrole-based COF: A computational study

Highly efficient removal of persistent organic pollutants (POPs) by novel porous materials such as covalent organic frameworks (COFs) has aroused widespread attention in environmental remediation. A thorough understanding on the removal mechanism lays a foundation for the material design. In the present work, the adsorption process of POPs on corrole-based COF (TPAPC) and their intrinsic interaction mechanism have been systematically investigated at the molecular level utilizing molecular dynamics (MD) simulations and density functional theory (DFT) calculations. A dynamic three-step adsorption pathway for POPs molecules, involving irregular movement, surface adsorption and interlayer transferring was vividly presented through the analysis of MD trajectory. TPAPC, especially its corrole moieties, exhibited tremendous adsorption capacity for POPs and the van der Waals (vdW) interaction played a dominant role during the adsorption process. Polychlorinated biphenyl (PCB) molecules (−2.15 ∼ −5.62 kcal/mol) exhibited much higher adsorption free energies than biphenyl (−0.68 kcal/mol), indicating their stronger binding capacities with TPAPC. Based on DFT calculations, the negative vdW potentials of corrole moiety and PCB molecules endowed them to become the preferable adsorption site and adsorbate, respectively. Our findings not only demonstrated that the corrole-based COF can be considered as a promising adsorbent for removing POPs but also provided a theoretical basis for designing novel COFs materials with specific functional groups such as corrole moiety in the field of environmental remediation.

Microbial dechlorination of polychrolinated biphenyls

Polychlorinated biphenyls (PCBs) are organic xenobiotics contaminating environment for at least 50 years. They could be eventually eliminated by various organisms under different conditions. The degree of chlorine substitution per biphenyl molecule influences biodegradability which decreases with increasing chlorination. Our work is focused on the PCBs biodegradation under anaerobic conditions. The suitable high chlorinated biphenyls are converted via reductive dechlorination to the chlorinated biphenyls with lower extent of chlorine, which could be eventually fully mineralized by aerobic bacteria. Microbial consortium was isolated from sediment of Strážský Creek (located near by plant producing PCBs in the past). This consortium was able to dechlorinate polychlorinated biphenyls under anoxic conditions. The effectiveness of this process was tested under different cultivation condition – different energetic sources (Aroclor 1248 or Aroclor 1260 or Delor 103 or Delor 106), addition of potential electron donors (pyruvate, lactate or acetate with hydrogen) and further if there is necessary to add yeast extract into fresh low sulphur cultivation media.
 Our microbial consortia so far do not need supplementation by non-contaminated sediment to maintain dechlorination activity. Addition of yeast extract is non essential, but needs to be further proved in serial transfers. In all cases (except acetate without yeast extract) dechlorination proceeds at meta- and flanked paraposition.

Retraction: Pressure regulated basis for gene transcription by delta-cell micro-compliance modeled in silico: Biphenyl, bisphenol and small molecule ligand models of cell contraction-expansion.

Retraction: Pressure regulated basis for gene transcription by delta-cell micro-compliance modeled in silico: Biphenyl, bisphenol and small molecule ligand models of cell contraction-expansion.

Effect of anchoring groups on the electronic transport properties of biphenyl and phenyl-pyridine molecules

Single-molecule quantum transport calculations are performed using nonequilibrium Green's functional formalism for biphenyl and phenyl-pyridine molecules asymmetrically anchored to gold electrodes via different edge groups. Clear current rectification is obtained depending on the edge group of the molecules with rectification level up to 4. Among the considered 6 structures, 4-mercaptophenyl-2,6-dithiolpyridine and 4′-mercaptomethyl-4-thiol-biphenyl molecules show the best diode parameters such as asymmetry, nonlinearity and responsivity, originating from bias-dependent charge localization in the systems as revealed in detailed analysis of the transmission eigenvalues and molecular projected self-consistent Hamiltonian states. The obtained results can be useful in developing molecular electronics devices, such as molecular diodes.