bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computing the structure of pillared Clays
Authors: Gale Julian D. , Cheetham Anthony K. , Jackson Robert A. , Callow C. Richard A. , Thomas John M. 
Published: December 2004

The behavior of an organic cation in a pillared clay has been successfully simulated taking into account both long‐range electrostatic interact‐ions and short‐range interactions between cation guests and host lattice. Anilinium cation pillars in vermiculite (a high charge density smectite) is the system studied and the simulations (e.g. see figure) compare favorably with the experimental 3D crystal structure.magnified image
Ferroelectric liquid crystalline polysiloxanes with high spontaneous polarization and possible applications in nonlinear optics
Authors: Kapitza Heinrich , Zentel Rudolf , Twieg Robert J. , Nguyen Cattien , Vallerien Sven Uwe , Kremer Friedrich , Willson C. Grant 
Published: December 2004

Ferroelectric liquid crystalline (LC) polymers (see figure), which in the smectic C* phase exhibit the highest yet known spontaneous polarization for LC polymers of up to 430 nC/cm2, a value which approaches that of the best low molecular weight materials, have been synthesized, based on chiral polysiloxanes. A copolymer is also reported which shows promise for second harmonic generation (frequency doubling) of the 1064 nm Nd:YAG fundamental (to 532 nm) without poling in an external field.magnified image
Charge transport in polyethylene–graphite composite materials
Authors: Ezquerra Tiberio A. , Kulescza Mareck , Cruz Carlos Santa , Baltá‐Calleja Francisco J. 
Published: December 2004

Deviation from the predictions of percolation theory for conduction in polythylene‐graphite composites (see figure) have been explained in tems of tunneling between the conducting graphite particles in the insulating polymer matrix, a mechanism which is believed to be prevalent at lower graphite concentration.magnified image
Liquid crystal polymers containing macroheterocyclic ligands 6. synthesis of mesomorphic polymers containing crown ethers by cationic cyclopolymerization and cyclocopolymerization of 1,2‐bis(2‐ethenyloxyethoxy)benzene derivatives containing mesogenic side groups
Authors: Rodenhouse Randall , Percec Virgil 
Published: December 2004

Communication: Side‐chain LCPs containing both a crown ether and a mesogenic group in each structural unit of the polymer are reported based on the monomer shown in the figure. Liquid crystals containing macroheterocyclic ligands are of interest since they provide a novel approach to self‐assembled systems which combine selective recognition with external regulation.magnified image
Superconducting organic thin films prepared using an evaporation technique
Authors: Kawabata Kazushige , Tanaka Keiji , Mizutani Makoto 
Published: December 2004

Research News: Superconducting organic thin films have been produced for the first time making use only of dry processes. The vacuum‐evaporation method is suitable for the production of thin films of BEDT‐TTF iodide either from electrochemically produced BEDT‐TTF iodide or directly from BEDT‐TTF and iodine. The insulating films formed in the deposition process are converted to the conducting form by annealing and analyzed using X‐ray diffraction (see Figure). The ‘dry’ nature of the process is advantageous as solvents can damage the fine crystals formed and make the production of homogeneous thin films difficult.
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Dye‐doped polymer films: From supramolecular photochemistry to the molecular computer
Authors: Wild Urs P. , Rebane Alexander , Renn Alois 
Published: December 2004

Research News: Hole burning in the spectra of dye‐doped polymer films provides the opportunity for high density data storage, holographic image storage and even five‐dimensional image storage is feasible (three spatial dimensions, frequency, and electric field). The background of the technique and recent progress in the optical data storage with lasers where impressive resolution and grey scales have been achieved (see Figure) is discussed.magnified image
Template synthesis of polymeric and metal microtubules
Authors: Martin Charles R. 
Published: December 2004

Research News: The pores in a microporous membrane can act as templates for the synthesis of polymeric and metallic microtubules. The tubules thus produced (see Figure) have monodispersed diameters and lengths and potential applications ranging from drug‐delivery systems to microwave components and in electronic and opto‐electronic devices.magnified image
Absorption spectra of charged oligo (phenylenevinylene)s: On the detection of polaronic and bipolaronic states
Authors: Schenk Rainer , Gregorius Heike , Müllen Klaus 
Published: December 2004

Communication: The effective conjugation length of poly(phenylenevinylene) an important conducting polymer, can be estimated by extrapolation of the results of UV/VIS/NIR studies of the radical anions and dianions of the soluble, well‐characterized oligo(phenylenevinylene)s shown in the figure. This information, in turn, is usefull in describing the mechanism of conduction in the polymer.magnified image
Correlation between primary chemical structure and property phenomena in polycondensates
Authors: Sommer Klaus 
Published: December 2004

AbstractPolycondensates (polycarbonates (PC), polyetherketones (PEK), and polyethersulfones (PES) in the present context) have an important share of the market for engineering and high‐performance thermoplastics. A knowledge of the relationships between the chemical structures of monomers and the properties of the polymers is an important prerequisite for the development of new plastics and the improvement of existing ones.These relationships can be investigated through the characterization of systematically varied polycondensate structures, and by the application of theoretical simulation methods developed to provide a better understanding of the propertydetermining structural elements and for the prediction of polymer characteristics.This article presents results relating to structure–property correlations (including various experimental results), static simulations of the amorphous polymer solid (“amorphous cell”) type, and dynamic Monte Carlo lattice simulations using the bond fluctuation algorithm.
Polymers for Nonlinear Optics
Authors: Buckley Alan 
Published: December 2004

AbstractNonlinear optical (NLO) materials provide the basis for an array of active optical devices under development throughout several high technology industries. Applications would include communications, data storage, and computing. Active optical devices can be used to alter light in order to encode or direct information in a number of ways. While the applications of optical technology such as fiber optics, optical storage and optical displays have identified a need for such devices, material properties have so far limited their introduction. Intensive, world‐wide, development of specifically designed polymers appears to offer the most attractive solution.
Crystal recognition at inorganic–organic interfaces: Nucleation and growth of oriented BaSO4 under Compressed Langmuir Monolayers
Authors: Heywood Brigid R. , Mann Stephen 
Published: December 2004

Controlling the size and oriented nucleation of inorganic cyrstals (e.g. see figure) through using organized assemblies of macromolecules can lead to new materials with interesting properties. In this paper, the general importance of stereochemical recognition in monolayer‐induced inorganic crystallization is examined by investigating the influence of three different anionic head groups on the oriented nucleation of BaSO4 magnified image
Reversed vesicles from biocornpatible surfactants
Authors: Kunieda Hironobu , Nakamura Kazuyoshi , Infante Maria Rosa , Solans Conxita 
Published: December 2004

The combination of hydrophilic and lipophilic amphiphiles and the addition of a small amount of water is demonstrated to be an effective method for the production of inversed vesicles (see figure) from biocompatible surfactant systems. Stable reversed vesicles would have applications in, for example, foods, medicines and cosmetics. magnified image
Progress towards processible materials for light‐emitting devices using poly(p‐phenylphenylenevinylene)
Authors: Vestweber Horst , Greiner Andreas , Lemmer Ulrich , Mahrt Rainer F. , Richert Ranko , Heitz Walter , Bässler Heinz 
Published: December 2004

Molecularly doped polymers are replacing inorganic photoreceptors in modern electrophotography. A future aim is to replace inorganic materials in light‐emitting diodes, but this required polymers that luminesce and are also processible in teir polymeric from. A promising candidate is poly(p‐phenylphenylenevinylene), shown in the figure. magnified image
Synthesis and reduction of 1,4‐phenylene‐bridged oligoporphyrins
Authors: Hammel Dirk , Erk Peler , Seliuler Barbara , Heinze Jürgen , Müllen Klaus 
Published: December 2004

The charge‐storage capability of oligoporphyrins (for example that shown in the figure) have been investigated. This has been made possible by the development of a straightforward synthesis of aryl‐substituted dipyrromethanes. magnified image
Polyrotaxanes: Molecular composites derived by physical linkage of cyclic and linear species
Authors: Gibson Harry W. , Marand Hervé 
Published: December 2004

Molecular composites consisting of cyclic molecules whose cavities have been pierced by linear molecules (see Figure) were discussed as early as 1910. However, recently interest in these molecules, which are known as rotaxanes, and their polymeric derivatives has intensified due to their unique property profiles which cannot be compared with those their components. Progress with rotaxanes and related compounds such as catenanes is reviewed. magnified image
AlH3(NMe3)2—a useful precursor to AlN
Authors: Rockensüß Wilfried , Roesky Herbert W. 
Published: December 2004

The high‐performance ceramic aluminum nitridehas a high resistance to heat and aggressive media. These properties depend to a large degree on the purity of the material. As a result much effort has been invested in the search for new precursors to AlN for use in methods such as metal‐organic chemical vapor deposition (MOCVD). The figure shows pure AlN powder produced from the title compound in an ammonia atmosphere.magnified image
Scanning tunneling microscopy of nanoscale electrodeposited superlattices
Authors: Switzer Jay A. , Golden Teresa D. 
Published: December 2004

Artificially layered superconductor materials based on crystalline multilayer structure are of potential interest due to the unusual quantum effects which could be expected in materials of this type. Scanning tunneling microscopy has recently been used (e.g. see Figure) to measure the modulation wavelength (the bilayer thickness) and to estimate the composition profile in such superlattices. magnified image
Photosensitized cross‐linking of Langmuir–Blodgett multilayers based on copoly(glutamate)s
Authors: Iida Shigeki , Schaub Mattias , Schulze Margit , Wegner Gerhard 
Published: December 2004

Rod‐like polymers of overall cylindrical shape dressed with a skin of flexible short side chains have been shown to be versatile building blocks for supramolecular structures. This paper describes the production of “molecular composites” based on such rigid rods, the mesoscopic structure of which is shown in the Figure. magnified image
Engineering oxide–oxide and metal–oxide microstructures in directionally solidified eutectics
Authors: Revcolevschi Alexandre , Dhalenne Guy 
Published: December 2004

Very regularly aligned composite structures made of the two phases of a eutectic can be fabricated by unidirectional solidification of eutectics from the melt. A recent innovation is the use of chemical reactions taking place at the eutectic interface to produce new aligned composite materials. An example of this can be seen in the Figure, an SEM micrograph of an Ni/NiO interface showing long forks of Ni in an oriented NiO–ZrO2(CaO) eutectic. magnified image
Metathesis Polymerization: ROMPing towards new materials
Authors: Gibson Vernon C. 
Published: December 2004

The introduction of a new generation of metathesis initiators (see Figure) in which the active site is incorporated within a relatively robust transition metal complex has had a significant impact on polymer synthesis. Key recent developments in the types of materials accessible, the control over microstructure possible, and the advantages of well‐defined initialtors for the design and synthesis of new materials are reviewed. magnified image
Fascinating phenomena in Surfactant Chemistry
Authors: Hoffmann Heinz 
Published: December 2004

AbstractAn amphiphilic compound such as a surfactant molecule is a very simple molecule. Yet, when dissolved in water, it spontaneously self‐assembles into a multitude of micellar structures such as globules, rods, disks, and vesicles. Even in dilute solutions containing only about 1 % of surfactant, these primary structures can organize themselves on a macroscopic scale so that the whole system in a test tube can be completely ordered. Such systems can have very remarkable macroscopic properties, for example, a yield stress, complex fluid behavior, or iridescence under illumination.The shape of the micellar structures is always determined by the area a that a surfactant molecule occupies at a micellar or bulk interphase. This area can be controlled or tuned by the mixing ratio X between surfactants or between surfactants and cosurfactants. The different assemblies which then result with the variation of X are discussed, together with the macroscopic properties of the systems and some applications where these properties are of use.
Germanium nanoclusters: Chemical vapor deposition of digermane in zeolite Y and mordenite
Authors: Dag ÖMer , Kuperman Alex , Ozin Geoffrey A. 
Published: December 2004

Uniform arrays of intrazeolite germanium nanoclusters have been produced by the topotactic chemical vapor deposition of digermane within the diamond network of α‐cages of acid zeolite Y and the main channel of mordenite. The conditions within the zeolite hosts enusure that the Ge2H6 CVD‐type anchored precursors self‐assemble to produce the anchored (Ge8)n⊕ nanoclusters shown in the Figure. magnified image
Iron(II) octaethyltetraazaporphyrin, FeOETAP, a canted ferromagnet with Tc = 5.6 K
Authors: Conklin Brenda J. , Sellers Scott P. , Fitzgerald Jeffrey P. , Yee Gordon T. 
Published: December 2004

A four‐coordinate azaporphyrin, FeOETAP (see Figure), is reported that has temperature‐ and field‐dependent properties different from those of other fourcoordinate iron(II) porphyrins and related macrocycles, displaying an apparent canted ferromagnetic state. This behavior is compared to that of M2⊕(OETAP), where M = Mn, Co, Ni, Cu, and Zn. magnified image
“Tailor‐Made” and charge‐transfer auxiliaries for the control of the crystal polymorphism of glycine
Authors: Weissbuch Isabelle , Leisorowitz Leslie , Lahav Meir 
Published: December 2004

Crystal polymorphism is important because of the different physical and mechanical properties of the polymorphs. Based on a stereochemical approach to controlling crystal polymorphism using stereospecific nucleation inhibitors, auxiliaries have been designed for the precipitation of the yform of glycine (see Figure) from aqueous solutions. The ideas behind this work are presented, together with results. magnified image
Scheibe Aggregates
Authors: Möbius Dietmar 
Published: December 2004

Scheibe agregates (J‐aggregates), highly ordered systems of strongly interacting chromophores (e.g. see figure), are characterized by a strong and narrow absorption band shifted to lower energy with respect to the band of the monomer, and a narrow resonance emission band with a very small Stokes shift. The formation of such aggregates, their organization and reorganization, their structure and their optical and photophysical properties are reviewed. magnified image
Polymeric Electro‐Optic Modulators: Matereials synthesis and processing
Authors: Dalton Larry R. , Harper Aaron W. , Wu Bo , Ghosn Rima , Laquindanum Joyce , Liang Ziyong , Hubbel Andrea , Xu Chengzeng 
Published: December 2004

The commercialization of new NLO materials will depend not only on the mastery of the technical problems but also on the availability of investment capital. Here, the research issues most relevant to commercialization are viewed and the advantages and disadvantages of new systems, both inorganic and organic, for example the cross‐linked thin‐film structure shown in the figure, presented and discussed. magnified image
Three–dimensional helical supramolecules—elucidation of magnetic ordering for an antiferromagnetic phase
Authors: Decurtins Silvio , Schmalle Helmut W. , Pellaux René , Huber Reto , Fischer Peter , Ouladdiaf Bachir 
Published: December 2004

A novel helical three‐dimensional supramolecular system has been investigated by neutron diffraction to determine the magnetic ordering in the antiferromagnetic phase. The representative system investigated (see Figure) is a MnII‐containing chiral network based on two types of preorganized transition‐metal complexes as complementary molecular partners that form a highly organized three‐dimensional supramolecular host–guest system. magnified image
Golden interfaces: The Surface of Self‐Assembled Monolayers
Authors: Delamarche Emmanuel. , Michel Bruno. , Biebuyck Hans A. , Gerber Christoph 
Published: December 2004

AbstractSelf‐assembled monolayers (SAMs) of alkanethiols and disulfides on gold form organic interfaces with properties largely controlled by the end groups of the molecules composing the film. SAMs provide a unique link between the science of organic surfaces and technologies that seek to exploit their adaptable character. Many techniques are useful for probing the structure of SAMs although only scanning tunneling microscopy (STM) at picoamperes reveals the details of the packing of their end groups at the sub‐angstrom level. This review demonstrates that STM effectively tests new types of control over the microscopic structure–property relationships characteristic of SAMs on gold that should prove useful to their application.
4,4′,4″‐Tris(stearoylamino)triphenylamine as a novel material for functional molecular gels
Authors: Yasuda Yoshiaki , Takebe Yasuo , Fukumoto Masahiro , Inada Hiroshi , Shirota Yasuhiko 
Published: December 2004

Electroactive organic molecular gels based on the title compound (see Figure) are reported along with their sol‐gel behavior and ionic conductivities, and their application as electrochromic materials is discussed. Furthermore the correlation between molecular structure and gel formation is examined in order to provide guidelines on the molecular design of gel‐forming organic materials. magnified image
Diffusions‐NMR‐Spektroskopie in der Supramolekularen und Kombinatorischen Chemie: ein alter Parameter – neue Erkenntnisse
Authors: Cohen Yoram , Avram Liat , Frish Limor 
Published: December 2004

AbstractIntermolekulare Wechselwirkungen in Lösung spielen eine wichtige Rolle bei der molekularen Erkennung und sind somit von besonderer Bedeutung in der Supramolekularen und Kombinatorischen Chemie. Die Untersuchung der molekularen Diffusion liefert Aufschlüsse über solche Wechselwirkungen, wobei sich die hochaufgelöste Diffusions‐NMR‐Spektroskopie als Methode der Wahl für die gleichzeitige Bestimmung von Diffusionskoeffizienten in einem Mehrkomponentensystem erwiesen hat. Der Diffusionskoeffizient ist dabei ein Maß für die effektive Größe und Form eines Moleküls. Zu den Anwendungen dieser Technik gehören die Abschätzung von Assoziationskonstanten, die Kartierung intermolekularer Wechselwirkungen in Mehrkomponentensystemen sowie Untersuchungen zum Aggregationsverhalten, zur Ionenpaarbildung, zur Bildung von Einschlussverbindungen und zur Bestimmung der Größe und Struktur von labilen Systemen. Mithilfe der Diffusions‐NMR‐Spektroskopie kann man aber auch Gemische virtuell auftrennen und gezielt nach Liganden für Rezeptoren suchen. Diese Methode kann so bei der Identifizierung von Leitverbindungen von Nutzen sein.
Studies on dextran and dextran derivatives. I. Properties of native dextran in different solvents
Authors: Antonini E. , Bellelli L. , Bruzzesi M. R. , Caputo A. , Chiancone E. , Rossi‐Fanelli A. 
Published: December 2004

AbstractLight‐scattering, sedimentation, viscosity, and reducing power measurements have been carried out on a sample of native dextran from Leuconostoc mesenteriodes B‐512. The results are discussed in relation to the structure, polydispersity, and branching of the polysaccharide. The effect of different solvents on the behavior of native dextran has been studied. The molecular weight of the dextran remains unchanged in all the solvents used, while the radius of gyration shows a significant increase in some of them (concentrated salts, urea, and glucose solutions); in water–methanol solutions the radius of gyration slightly decreases.
The method for estimation of chain macromolecule rigidity
Authors: Golub E. I. 
Published: December 2004

AbstractBirefringence relaxation times on removing the electric field characterize the rigidity of a flexible linear macromolecule structure. Electrical birefringence investigation of DNA solutions supports this view. This principal regularities displayed by relaxation times of electric birefringence decay curves in solutions of chain macromolecules are considered.
Proton magnetic resonance study of the binding of purine to polyuridylic acid
Authors: Bangerter Benedict W. , Chan Sunney I. 
Published: December 2004

AbstractThe interaction of unsubstituted purine with polyuridylic acid in D2O solution at neutral pD has been studied by high resolution proton magnetic resonance spectroscopy. The poly U proton resonances were shifted to higher fields by the added purine, indicating that purine binds to the uracil bases of the polymer by base stacking. Severe broadening of the purine proton resonances was also observed, providing strong evidence for the intercalation of purine between adjacent uracil bases of the polymer. The line widths of the poly U proton resonances were not noticeably broadened in the presence of purine; thus, the binding of purine to poly U does not result in a more rigid or ordered structure for the polymer.
Cesium chloride density distributions in preparative equilibrium ultracentrifugation
Authors: Rüst Peter 
Published: December 2004

AbstractA computer program has been developed for calculating equilibrium centrifugation density distributions by direct integration of tabulated data, which eliminates curve fitting. Error calculations showed that a high accuracy is required for the measurement of the data needed a determine a density distribution either by computation or by direct measurements. In particular, the variation in drop size during the fractionation of the contents of a centrifuge tube have been investigated by computer simulation. A direct measurement of the drop size indicated that it may increase somewhat during collection. In addition, plots are presented of the dependence upon seven parameters of the centrifugation required to approach equilibrium to a desired degree (based on the formula of Van Holde and Baldwin).