Linear Polyphenyls Research Articles

Formation of helical polyphenyl nanostructures on carbon nanotubes

In this manuscript, helical polyphenyl (PP) nanostructures were formed on single-wall carbon nanotubes (SWCNT) through self-assemble process which was investigated by a molecular dynamics simulation. The results displayed that the linear polyphenyl changed into helical structure and finally a core–shell structure was formed. The formation mechanism of whole process was also exhibited. Furthermore, some influence factors such as the initial angle between polyphenyl chain and nanotube axis, the diameter of carbon nanotube were also displayed. Moreover, the interactions between different halogenated benzene polymer and carbon nanotube were also studied. The new geometrical structures between polyphenyl and single-wall carbon nanotubes may attract more attention in chemical functionalization and helical polymer synthesis, which may be helpful for fabricating nanoscale devices.

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series.

Arenes undergo rearrangement of phenyl, alkyl, halogen and other groups through the intermediacy of ipso arenium ions in which a proton is attached at the same carbon as the migrating substituent. Interconversions among the six quaterphenyl isomers have been studied here as a model for rearrangements of linear polyphenyls. All reactions were carried out in 1 M CF3SO3H (TfOH) in dichloroethane at 150 °C in a microwave reactor for 30–60 min, with product formation assessed by high field NMR analysis. Under these reaction conditions, m,p'-quaterphenyl is the equilibrium product. This isomer is unchanged by the reaction conditions and all other quaterphenyl isomers rearrange to m,p' as the dominant or sole product. DFT computations with inclusion of implicit solvation support a complex network of phenyl and biphenyl shifts, with barriers to rearrangement in the range of 10–21 kcal/mol. Consistent with experiments, the lowest energy arenium ion located on this surface is due to protonation of m,p'-quaterphenyl. This supports thermodynamic control based on carbocation energies.

On-Surface Synthesis of Linear Polyphenyl Wires Guided by Surface Steric Effect

Tailoring functionalized nanostructures at the atomic scale is of importance in nanotechnology. We report on the controllable fabrication of linear polyphenyl wires by direct C–H activation and C–C coupling of para-sexiphenyl (p-6P) on an anisotropic Au(110) surface. Because of the one-dimensional spatial constraint at the surface, the equivalent C–H bonds of p-6P molecules were differentiated with various reaction probabilities. Consequently, linear polymerization of p-6P was achieved via C–C bonding at the meta-sites, with the kink formation every 6 phenylene units. On the other hand, branched polymerization was efficiently suppressed. Among such kinked polyphenyl wires, the trans conformation is predominant, compared with the cis conformation. Furthermore, exclusive C–C bond formation at the p-6P para-sites has been promoted by the neighboring terphenyl radicals, which possess reactive para-sites, resulting in the formation of straight para-polyphenyl wires instead of kinked ones. Our study demonstrate...

Five-vertex Archimedean surface tessellation by lanthanide-directed molecular self-assembly

The tessellation of the Euclidean plane by regular polygons has been contemplated since ancient times and presents intriguing aspects embracing mathematics, art, and crystallography. Significant efforts were devoted to engineer specific 2D interfacial tessellations at the molecular level, but periodic patterns with distinct five-vertex motifs remained elusive. Here, we report a direct scanning tunneling microscopy investigation on the cerium-directed assembly of linear polyphenyl molecular linkers with terminal carbonitrile groups on a smooth Ag(111) noble-metal surface. We demonstrate the spontaneous formation of fivefold Ce-ligand coordination motifs, which are planar and flexible, such that vertices connecting simultaneously trigonal and square polygons can be expressed. By tuning the concentration and the stoichiometric ratio of rare-earth metal centers to ligands, a hierarchic assembly with dodecameric units and a surface-confined metal-organic coordination network yielding the semiregular Archimedean snub square tiling could be fabricated.

Enumerating tree-like polyphenyl isomers

Enumeration of molecules is one of the fundamental problems in bioinformatics and plays an important role in drug discovery, experimental structure elucidation (e.g., by using NMR or mass spectrometry), molecular design and virtual library construction. We consider the enumeration of tree-like polyphenyls (C6nH4n+2). For this purpose, we define two generating functions T(x) and R(x) involving the numbers tn and rn of tree-like polyphenyls (TL-polyphenyls) and monosubstituted tree-like polyphenyls (MTL-polyphenyls), respectively. By characterizing the symmetry groups with respect to TL-polyphenyls and MTL-polyphenyls, we establish two functional equations for these two generating functions. This yields for the first time an efficient recursion formula for calculating the numbers tn and rn. The two functional equations are also the fundamentals for analyzing their asymptotic behaviors, from which we derive the precise asymptotic values for both rn and tn. The resulting asymptotic values are shown to fit well to the numerical results obtained by using our recursion formula. Finally, we give an explicit enumerating expression for TL-polyphenyls of a particular type: the linear polyphenyls.

Estudio cinético del efecto de polifenilsulfona sobre el curado de una resina epoxi/amina mediante calorimetría diferencial de barrido convencional y modulada con temperatura: parte II

En este trabajo se estudió el efecto de la adición del termoplástico lineal polifenilsulfona (PPSU), sobre la cinética de reacción y las propiedades térmicas de una resina epoxídica basada en diglicidil éter de bisfenol - A (DGEBA), curada con diaminodifenilsulfona (DDS). El estudio cinético y la caracterización se realizaron mediante calorimetría diferencial de barrido, DSC estándar y modulado, bajo condiciones isotérmicas y dinámicas. La cinética del curado se discutió en el marco de tres modelos cinéticos: Kissinger, Flynn-Wall-Ozawa y el modelo cinético de orden n. Para describir la reacción de curado en su última etapa, se usó la relación semiempírica propuesta por Chern y Poehlein para considerar la influencia de la difusión sobre la rapidez de reacción. El mecanismo de curado, para todos los sistemas, se ajustó a una cinética de orden n, a pesar del contenido de PPSU, y se observó que éste se hace muy controlado por la difusión conforme aumenta el contenido de PPSU y conforme la temperatura de curado disminuye. El tiempo de vitrificación de los sistemas exhibió una fuerte dependencia con el contenido de PPSU.

Enantiomerization of bridged 1,1′‐binaphthyls

AbstractThe activation energy for the isomerization of 1,1′‐binaphthyl in which positions 2 and 2′ are bridged at by an —O—CH2—O— unit was calculated at various computational levels. AM1 gave good agreement with the experimental results. The transition‐state structure was found to be entirely different from that calculated for the non‐bridged parent compound: whereas the latter has C2 symmetry, the former has C s symmetry. The C s symmetry transition state for the non‐bridged parent compound was also located and found to be ca 6 kcal mol−1 higher than the C2 one. However, in the bridged compound, the inclusion of the bridge counterbalanced this by raising the energy of the ground state, leaving the activation energy essentially unchanged. The isomerization of optically active bridged 1,1′‐binaphthyls bearing linear polyphenyl rods of varying length, at positions 6 and 6′, was recently employed as a probe to gain information on the effect of rubber and glassy polymers on reaction rates. The model showed that the rod segments of these molecules traverse long distances in order to reach the transition state, which was consistent with a strong rod length dependence on racemization of the bridged binaphthyls in the glassy state. However, the present results demonstrate an unexpected twisting motion in the racemization process, suggesting that the appended oligophenyl rods are displaced to about half the distance previously expected. This may contribute in part to the experimental observation in the rubbery state where the microviscosity affects the racemization as a function of the appended rods far less than expected. AM1 results also gave reasonable agreement with the experimental ponderal effect consistent with the prior conclusion of force constant independence of rod length for twisting about the 1,1′ bonds. Copyright © 2002 John Wiley & Sons, Ltd.

Brillouin Scattering Study on o-Terphenyl Single Crystal

Elastic waves in the o-terphenyl single crystal belonging to the orthorhombic system were measured by the Brillouin light-scattering spectroscopy. Wave vectors of elastic waves were obtained from three principal values of dielectric tensor determined by a new simple method. All nine elastic constants representing elastic contribution to the free energy have been determined, which show intermediate anisotropy between benzene and linear polyphenyls. The anisotropy can reasonably be explained from the arrangement of the phenyl bonds and the inter-molecular interactions caused from the packing of molecules in the crystalline lattice. It has been found that pure transverse elastic waves would not be observed in this system by the Brillouin scattering.

Charge-transfer Complexes, Gas-liquid Chromatographic and Photochemical Characteristics, and Solvent Adducts of Polyphenylenes and Related Linear Polyphenylsls

Abstract The absorption spectra of the charge-transfer (CT) complexes formed by two acceptors (tetracyanoethylene and 2,3-dichloro-5,6-dicyano-p-benzoquinone) with thirteen macrocyclic polyphenylenes and with thirty-eight linear polyphenyls were measured in dichloromethane. A linear relationship existing between the first transitions of the CT-complexes and those of the uncomplexed donor hydrocarbons made it possible to predict the CT-bands of new polyphenylenes and polyphenyls. By the gas-liquid chromatography using a glass capillary column, forty-nine polyphenyls and polyphenylenes, containing a large number of isomers, were successfully analyzed. The relationship between the retention times and the structure of linear polyphenyls was expressed by means of a simple empirical equation, and the equation was also applicable to the polyphenylenes by adding a correction factor. These equations are extremely useful for the estimation of the retention time and elution order and the structure of unknown polyphenyls and polyphenylenes. The reductive irradiation of m,m,o,p,o-pentaphenylene provided the bridged annulene compound. For six polyphenylenes and the related compounds, the criteria for the occurrence of the intramolecular photocoupling reaction were discussed. Among the examined polyphenylenes, m,o,o,m,o,o-hexaphenylene and o,p,p,o,p,p,o,p,p-nonaphenylene formed the adducts with several solvents.

Syntheses and spectral characteristics of seven polyphenyls containing highly branched para-phenylene ring(s).

Seven polyphenyls, including four new compounds, 2, 2', 6'- (2) and 3, 2', 6'-triphenyl-p-terphenyl (3), 3', 5'-diphenyl-p-quaterphenyl (4), and 2-phenyl-3'-(2-biphenylyl)-p-terphenyl (7), were synthesized by the Ullmann coupling reaction of aryl iodide (s) or by the Kharash-type coupling reaction of aryl Grignard reagent with an aryl iodide catalyzed by bis (acetylacetonato)-nickel (II). Infrared spectral studies of the polyphenyls showed that the range of 730-770 cm-1, generally accepted as the position of the out-of-plane C-H bending bands of the phenyl ring, should be widened slightly to 730-786 cm-1. The high frequency bands were confirmed to be correlated closely to the overcrowding by terminal rings in the complex structures. Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the branched polyphenyls were fully consistent with their conformational aspects deduced from stereomodels. In the ultraviolet spectral studies the polyphenyls containing highly branched p-phenylene ring (s) showed intense K-bands or shoulders at locations very similar to those of the corresponding linear polyphenyls containing the same number of p-phenylene rings.

Epitaxial crystallization of selenium on linear polyphenyls

Selenium has been crystallized in the presence of linear polyphenyls, namelyp-ter andp-quaterphenyl, crystals by reheating from the glassy state to temperatures in the range 80 to 180°C. Oriented growth of selenium is observed. The epitaxial relationship is based on lattice matchings parallel and normal to the selenium chains. Similarities with epitaxial growth of polyethylene on the same organic substrates are discussed.

Epitaxial crystallization of polyethylene on organic substrates: A reappraisal of the mode of action of selected nucleating agents

AbstractElectron microscopy and electron diffraction studies show that polyethylene crystallizes epitaxially onto crystals of homologous series of (i) condensed aromatic hydrocarbons and (ii) linear polyphenyls. The contact planes of the PE chain‐folded lamellae with the (001) faces of the substrate crystals are found to differ for the two series, being (100) and (110), respectively. The underlying epitaxial relationships are best explained by a two‐dimensional lattice matching of polymer and substrate networks. In view of the structural similarities of the present substrates and some well‐known nucleating agents for polyethylene, epitaxy is suggested as a possible mechanism which could explain the nucleating ability of the latter. This is experimentally demonstrated with the potassium salt of phthalic acid.

Epitaxial crystallization of aliphatic polyesters on trioxane and various aromatic hydrocarbons

AbstractLinear polyesters of the diacid‐dialcohol type are observed to crystallize epitaxially onto substrate crystals of trioxane, condensed aromatic hydrocarbons, and linear polyphenyls. In line with results previously reported for PE, lattice matching requirements for epitaxy lead to a change in the polymer contact plane on the different substrates. The highly oriented, sometimes single‐crystal‐like polymer films are formed of stacks of lamellae seen edge on which appear well suited to investigations of the lamellar structure.

ChemInform Abstract: STUDIES OF POLYPHENYLS AND POLYPHENYLENES. II. THE SYNTHESIS AND PHYSICAL PROPERTIES OF POLYPHENYLS CONTAINING PARA LINKAGE

AbstractDie Quinquephenyle (I), (II), (III), (IVa) und (IVb) sowie die Polyphenyle (IVc)‐(IVe) werden durch Ul1mann‐Reaktion entspr chender Iodbiphenyle ( ;z.B. (VII), (VIII)) mit Diiodbenzolen ( ;z.B. (VI), (IX), (XI)) oder Iodterphenylen ( ;z.B. (X)) synthetisiert (als weitere Produkte dieser Reaktionen treten Biphenyl, 0‐, p‐Terphenyl, 0‐, m‐, p‐Quaterphenyl, p‐Sexiphenyl auf (Tabelle)).

Studies of Polyphenyls and Polyphenylenes. II. The Synthesis and Physical Properties of Polyphenyls Containing Para Linkage

Abstract Twelve linear polyphenyls, including quinque- to octiphenyl, were synthesized by the Ullmann cross-coupling reaction of iodobiphenyl with diiodobenzene or iodoterphenyl. Ultraviolet spectral studies of the polyphenyls indicated that the positions of the K-bands above ca. 260 nm, regardless of the presence of o- or m-phenylene unit(s), may be considered to be an indication of the approximate number of consecutive p-phenylene units. Infrared studies also showed that the locations of strong or medium bands in the 815–850 cm−1 region may give the same information. The HMO calculations of the longest wavelength absorption bands of twenty-four polyphenyls were carried out. A comparison between the calculated and observed wavelengths gave rather good agreement, except in the cases of two compounds. The signals of the proton magnetic resonance spectra of eighteen polyphenyls were assigned tentatively. The correlations between the arrangement of the benzene rings and the spectral patterns are discussed.

Fluorescence and sensitization properties of linear polyphenyls

Linear p-polyphenyls in solutions show a conformational change in the excited state. In these compounds the aromatic rings are not coplanar owing to the presence of strong steric hindrance at the ortho positions. In the excited states the distortion angles are changed. As a result an effective separation of the absorption and emission bands is possible and the energy transfer from the solvent to the solute is irreversible [1]. This irreversibility causes that the mentioned molecules are good scintillators and their fluorescence was studied in several works. However, no data are available concerning their fluorescence in adsorbed state. Another interesting question is whether these non-coplanar aromatic rings show sensitization (donor) properties. The aim of this paper is to compare the fluorescence of different p-polyphenyls [biphenyl; p-terphenyl; p-quaterphenyl and 4,4‴-bis (2-butyloetoxy)-p-quaterphenyl or BIBUQ] in solution, in crystalline and in adsorbed state as well as the investigation of sensitized fluorescence in the naphthacene/p-polyphenyl systems on solid surfaces.

Phase Behavior of Some Linear Polyphenyls

(1979). Phase Behavior of Some Linear Polyphenyls. Molecular Crystals and Liquid Crystals: Vol. 49, No. 7, pp. 207-209.

Pressure dependence of the lattice parameters of anthracene up to 5.4 kbar and a re-evaluation of the elastic constants

The lattice parameters of an anthracene crystal were measured as functions of hydrostatic pressure in the pressure range from 0–5.4 kbar using neutron diffraction techniques. The results were found to agree with previous measurements of the volume compressibility of anthracene and, in the a and b directions, with the values extrapolated from linear compressibility data for linear polyphenyls. The values of the linear compressibilities were used to derive an improved set of elastic constants from currently available velocity of sound data.

Liquid scintillators X. Some aryl substituted phenanthrenes and dihydrophenanthrenes, and relatedp-terphenyls andp-quaterphenyls determination of Kallmann parameters

A number of new 2- and 2,7-aryl substituted phenanthrenes, 3,4-dihydrophenanthrenes, and 9,10-dihydrophenanthrenes, as well as some relatedp-quaterphenyls andp-terphenyls, were tested as liquid scintillation solutes. Also determined were the compounds' ultraviolet absorption spectra, ultraviolet-induced fluorescence spectra, and Kallmann parameters. On the basis of these measurements, it was possible to correlate to some degree structure and scintillation ability. Some interesting results regarding conjugation and co-planarity in the linear polyphenyls were also obtained.

The Synthesis of Some Linear Polyphenyls

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Synthesis of Some Linear PolyphenylsG. Forrest Woods, David D. Centola, Howard E. Ruskie, and C. David MillerCite this: J. Am. Chem. Soc. 1960, 82, 19, 5227–5232Publication Date (Print):October 1, 1960Publication History Published online1 May 2002Published inissue 1 October 1960https://doi.org/10.1021/ja01504a050RIGHTS & PERMISSIONSArticle Views229Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (650 KB) Get e-Alerts Get e-Alerts