bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas phase molecular modeling of liquid crystals: Electro‐optical anisotropies
Authors: Bremer Matthias , Tarumi Kazuaki 
Published: May 2005

Molecular modeling of liquid crystals is important as it provides information without the need for chemical synthesis. The first ever quantitative correlation of semiempirically obtained quantities with electro‐optical parameters measured in 80 bulk liquid crystals is reported here. The Figure shows the calculated relative energy of an LC as a function of two torsion angles. magnified image
Side chain influence on mesomorphic properties: Low‐temperature melting of metal‐containing liquid crystals
Authors: Maldivi Pascal , Bonnet Laurence , Giroud‐Godquin Anne‐Marie , Ibn‐Elhaj Mohammed , Guillon Daniel , Skoulios Antoine 
Published: May 2005

Metal‐containing liquid crystals offer the possibility of obtaining mesogenic materials with novel electronic properties. However, the transition temperatures need to be reduced before applications can be found. The authors describe the first fully characterized metallomesogens with an authentic columnar mesophase near room temperature, which were obtained by inserting carbon‐carbon double bonds as the “R” group in te carboxylate ligands (see Figure). magnified image
Ultrathin films of cellulose on silicon wafers
Authors: Schaub Matthias , Wenz Gerhard , Wegner Gerhard , Stein Andreas , Klemm Dieter 
Published: May 2005

The first preparation of thin films of cellulose itself is reported. Cellulose exhibits excellent wetting behavior, is extremely stable against oxidation and other chemical degradation and in thin‐film form would have a number of applications. The method involves the preparation of LB films of trimethylcellulose (see Figure) and the in situ conversion of these thin films on silicon substrates to cellulose. magnified image
Highly ordered films of neat calix[4]arenes for second order nonlinear optics
Authors: Kelderman Erik , Heesink Gerard J. T. , Derhaeg Lode , Verbiest Thierry , Klaase Piet T. A. , Verboom Willem , Engbersen Johan F. J. , van Hulst Niek F. , Clays Koen , Persoons Andre , Reinhoudt David N. 
Published: May 2005

In substituted calix[4]‐arenes—cyclophanes consisting of four phenol moieties connected by methylene bridgesthe number and also the relative positions of the donor and/or acceptor π‐conjugated (D‐π‐A) units can be varied by changing the configuration. The Figure illustrates the cone configuration. The molecular and thin‐film NLO properties of three tetra‐D‐π‐A‐substituted calix[4]arenes, including their orientation in thin films and the stability of their NLO properties, are described. magnified image
Scanning probe surface modification
Authors: Corbitt Thomas S. , Crooks Richard M. , Ross Claudia B. , Hampden‐Smith Mark J. , Schoer Jonathan K. 
Published: May 2005

Nanometer‐scale manipulation of surfaces by scanning probe devices has expanded amazingly since the first reports in the mid‐1980s. General approaches to scanning probe microscope induced surface patterning are discussed. The Figure shows a scanning electron micrograph of an STM‐defined pattern of a HS(CH2)17CH3 monolayer resist on a Au(111) substrate. magnified image
Molecular Magnetism: A basis for new materials
Authors: Gatteschi Dante 
Published: May 2005

Molecular magnetism, which includes the study of organic magnets, spin cross‐over, and large spin clusters, has recently begun to concentrate on the design and synthesis of new magnetic compounds. Simple molecules, based on nitroxides and nitronyl nitroxides (see Figure), have been found to order ferromagnetically. The field is reviewed, stressing the possibility of combining properties. magnified image
Scanning probe microscopy study of the incommensurate modulation and surface defects in the layered telluride TaGe0.355Te2
Authors: Bengel Hardy , Cantow Hans‐Joachim , Magonov Sergei N. , Monconduit Laure , Evain Michel , Liang Weigen , Whangho Myung‐Hwan 
Published: May 2005

The detection of atomic‐size defects by atomic force microscopy (AFM) is demonstrated. For example, the dark grooves in the image of the surface of the incommensurate layered telluride phase TaGe0.355Te2 (see Figure) indicate a defect. The origin of this incommensurate structure of layered tellurides is established and it is shown that high applied forces enhance the image contrast in AFM. magnified image
Paramagnetic metal‐containing mesogenic polyazomethines
Authors: Alonso Pablo J. , Martínez Jesús I. , Oriol Luis , Piñol Milagros , Serrano José Luis 
Published: May 2005

Paramagnetic moieties in mesogenic polymers can provide valuable information about macromolecular orientation. The results of EPR and polarized light investigations on three polyazomethines bearing hydroxyl groups and containing paramagnetic centers are reported. The micrograph in the Figure shows the threaded texture of a polyazomethine, derived from naphthalenediamine, containing oxovanadium(IV) centers. magnified image
Voltammetric studies of solution and solid‐state properties of monodisperse oligo(p‐phenylenevinylene)s
Authors: Meerholz Klaus , Gregorius Heike , Müllen Klaus , Heinze Jürgen 
Published: May 2005

Four well‐defined monodisperse oligo(p‐phenylenevinylene)s (see Figure, n = 3 to 6) have been used in solid‐state voltammetric investigations as model compounds for the related polymer. The redox behavior in solution and in the solid state is compared and an interpretation of the controversial “current plateau” proposed. magnified image
Thermally stable multilared organic electroluminescent devices using novel starburst molecules, 4,4′,4″‐Tri(N‐carbazolyl)triphenylamine (TCTA) and 4,4′,4″‐Tris(3‐methylphenylphenylamino)triphenylamine (m‐MTDATA), as hole‐transport materials
Authors: Kuwabara Yoshiyuki , Ogawa Hiromitsu , Inada Hiroshi , Noma Naoki , Shirota Yasuhiko 
Published: May 2005

Organic electroluminescent devices with improced thermal stability and good performance characteristics are reported. The hole‐transport material is a novel π‐electron “starburst” molecule, TCTA (see Figure), whose glass‐transition temperature is increased by the introduction of a structurally rigid moiety. magnified image
In situ X‐ray diffraction evidence of guest molecule reorientation during an intercalation reaction
Authors: Evans John S. O. , Barlow Stephen , Wong Heng‐Vee , O'Hare Dermot 
Published: May 2005

Superconductivity and co‐operative magnetism are just two of the interesting features of materials based on the intercalation of organic or organometallic moieties into lamellar host lattices. In situ energ dispersive X‐ray diffraction is used here to probe the kinetic and mechanistic details of guest reorientation during intercalation (see Figure). magnified image
Three‐dimensional woven glass fabrics
Authors: Alba Juan J. , Miravete Antonio 
Published: May 2005

Textile composites are a class of materials in which reinforcement is provided by textile performs. Owing to their unique combination of light weight, flexibility, strength, and toughness these materials have been used in reinforcement in both structural and other applications. New applications i advanced structural composites using 3‐D braiding (see Figure) are reviewed. magnified image
High temperature superconducting materials
Authors: Alario‐Franco Miguel Angel 
Published: May 2005

The perovskite structure (see Figure) is the basis of all known high‐temperature superconducting materials. Many of the most successful (ighest Tc) materials are based on mercury and thallium phases but, due to the high toxicity of the component compoudns effort has been invested in the substitution of these elements with silver. Progress is reviewed. magnified image
Dielectrics for Field Effect Technology
Authors: Balk Pieter 
Published: May 2005

AbstractThe availability of stable MOS gate systems and high density storage capacitors is an essential requirement for the development of the field effect storage technology. For standard MOSFET gates this role has been fulfilled by SiO2grown by thermal oxidation of the Si substrate. Improved insight into the properties of the Si/Si02system and perfection of its growth technology will secure its role in Si MOSFET memories for the future. For charge storage application the stability requirements are less demanding. However, here SiO2is not able to provide sufficient capacity. In this case higher dielectric constant materials (Si3N4or Ta2O5) have to take over. Particularly attractive appears the use of ferroelectrics. These dielectric materials not only offer a high dielectric constant, but also the perspective of providing non‐volatile storage in capacitor structures.
Synthesis of AIPO4‐5 aluminumphosphate molecular sieve crystals for membrane applications by microwave heating**
Authors: Girnus Irina , Pohl Marga‐Martina , Richter‐Mendau Jürgen , Schneider Matthias , Noack Manfred , Venzke Dieter , Caro Jürgen 
Published: May 2005

Aluminum phosphate molecular sieves with well‐shaped hexagonal column‐like morpholgoy (see Figure) have been produced by applying microwave heating to a gel. The crystals are effective materials for application in one‐dimensional membranes for molecular sieving. As can be seen in the figure, crystals containing a central tubular void can also be produced magnified image.
Polar inclusion compounds of perhydrotriphenylene (phtp) and efficient nonlinear optical molecules**
Authors: Hulliger Jürg , König Olaf , Hoss Ralf 
Published: May 2005

Host lattices based on piperazines, which can include a large variety of linear “rod‐shaped” π systems, are presented. One example is the inclusion of efficient nonlinear optical molecules (e.g. see Figure, and the cover picture this month) which leads to materials exhibiting attractive electro‐optical properties magnified image.
Preparation of a flexible polyaniline‐pvc composite
Authors: Conn Costa , Booth Norman , Unsworth Joe 
Published: May 2005

An inexpensive, highly conducting polymer‐thermoplastic composite material is reported which is both flexible and possesse a low percolation threshold. The method used to prepare the PANI‐PVC material “see Figure” allows control of the flexibility of the product through the use of commercially available plasticizers magnified image.
Liquid crystals based on 2‐ fluoropyrimidine and ‐pyridine: synthesis, dielectric anisotropy and phase behavior*
Authors: Bremer Matthias 
Published: May 2005

Polar liquid crystals with strongly positive dielectric anisotropies are of continuing interest to the display industry because theyhelp to lower both the operating voltage and the total power consumption of LCDs in portable devices. Fluorinated heterocyclic materials “Figure, right, MG = mesogenic group” are shown here to exhibit impoved mesophase properties and higher dielectric and optical anisotropies than commonly used materials used in the purely fluorine substituted moietie magnified image.
Wavelength dependance in laser floating zone processing. A case study with bi‐SR‐CA‐CU‐O superconductors*
Authors: de la Fuente German F. , Carlos Diez Juan , Angurel Luis A. , Peña JoséI. , Sotelo Andre , Navarro Rafael 
Published: May 2005

Laser floating zone processing methods are particularly suitable for studying crystal growth and the development of texture from the melt in many materials used n electrooptics, for example. A system is descrbed that allows different laser wavelengths to be used, and first results on BSCCO superconducting fibers processed using different lasers are presented. The Figure compares textures produced using Nd:YAG and CO2 lasers magnified image.
Push‐pull substituted polythiophenes: towards charge confinement in molecular quantum wells
Authors: Demanze Frederic , Yassar Abderrahim , Garnier Francis 
Published: May 2005

Poly(bithiophene) dervatives unsymmetrically substituted with strong electron‐donating groups and strong electron‐withdrawing groups (e.g. see Fig.) have been synthesized. The substituents induce electronic push–pull effects along the conjugated chain which could be exploited in the design of organic‐based multiple quantum well structures magnified image.
Design of a solvatochromic polymer‐based fiber optics chemical sensor for polar solvent detection*
Authors: Fichou Denis , Hubert Christine , Garnier Francis 
Published: May 2005

An optical sensor for organic solvents with a detection limit of 10−2 v/v‐% for methanol in mixed hydrocarbons is presented. The system, a fiber optic chemical sensor based on Reichardt's dye covalently bound to an insoluble Merrifield peptide resin (see Fig.), is shown to have a response time of ca. 1 minute magnified image.
Effective synthesis of HgBa2Ca2CU308+y, the highest Tc superconductor*
Authors: Peacock Graeme B. , Ganzeson Ian , Zhou Wuzhong , Edwards Peter P. , Slaski Marcin , Zhou Wuzhong , Cooper John R. 
Published: May 2005

The preparation of the superconductor Hg‐1223 (see this month's title picture) with 60‐70% phase purity by a simplified route is reported. The material is produced in a single step from air‐stable mono‐oxides and exhibits a sharp superconducting transition, possibly due to the lack of observable defects (see Fig.) magnified image.
Novel ceramic particle synthesis for optical applications: Dispersion polymerized preceramic polymers as size templates for fine ceramic powders
Authors: Beecroft Laura L. , Ober Christopher K. 
Published: May 2005

A shape template for small ceramic particles (see figure) is provided by the dispersion polymerization of preceramic polymers. The particle size can be closely controlled through adjusting the reaction conditions, allowing the design of materials for applications as diverse as optical composite materials, catalyst supports, and particulate reinforcement magnified image.
Self‐organized phases combined with IDC devices‐switchable materials for solvent vapor detection
Authors: Dickert Franz L. , Keppler Monika 
Published: May 2005

A new concept for analyte detection based on the combination of interdigitated capacitor technology with supramolecular structures (see this month's cover picture) is presented. Analyte molecules disturb the hydrogen bonds between pyridone units, and it is this structure‐breaking effect (see figure) which is the basis of the sensor detection magnified image.
Bioactive silicon structure fabrication through nanoetching techniques
Authors: Canham Leigh T. 
Published: May 2005

A microporous film of silicon is shown to induce hydroxyapatite growth both on itself and on neighboring areas of bulk silicon (e.g. see figure). This indicates that silicon could be developed as an active biomaterial, which has encouraging implications for the use of VLSI technology in, for example, invasive sensing and biosensing and other electronic prosthetic devices magnified image.
Polymer Layered Silicate Nanocomposites
Authors: Giannelis Emmanuel P. 
Published: May 2005

AbstractPolymer nanocomposites with layered silicates as the inorganic phase (reinforcement) are discussed. The materials design and synthesis rely on the ability of layered silicates to intercalate in the galleries between their layers a wide range of monomers and polymers. Special emphasis is placed on a new, versatile and environmentally benign synthesis approach by polymer melt intercalation. In contrast to in‐situ polymerization and solution intercalation, melt intercalation involves mixing the layered silicate with the polymer and heating the mixture above the softening point of the polymer. Compatibility with various polymers is accomplished by derivatizing the silicates with alkyl ammonium cations via an ion exchange reaction. By fine‐tuning the surface characteristics nanodispersion (i. e. intercalation or delamination) can be accomplished. The resulting polymer layered silicate (PLS) nanocomposites exhibit properties dramatically different from their more conventional counterparts. For example, PLS nanocomposites can attain a particular degree of stiffness, strength and barrier properties with far less inorganic content than comparable glass‐ or mineral reinforced polymers and, therefore, they are far lighter in weight. In addition, PLS nanocomposites exhibit significant increase in thermal stability as well as self‐extinguishing characteristics. The combination of improved properties, convenient processing and low cost has already led to a few commercial applications with more currently under development.
A novel thermoset polymer optical fiber
Authors: Flipsen Theo A. C. , Steendam Rob , Pennings Albert J. , Hadziioannou Georges 
Published: May 2005

Polymer optical fibers are being investigated with a view to overcoming some of the disadvantages of glass optical fibers in communications applications. Dense cross‐linked polymers, such as the polyisocyanurate discussed here (see figure), have been found to be superior in some respects to the thermoplastic polymers used today. Details are given of the fabrication of a polyisocyanurate network using a rare‐earth complex as a catalyst. magnified image
Regularly interstratified layered silicate heterostructures: Precursors to pillared rectorite‐like intercalates
Authors: Ijdo Wouter L. , Lee Ton , Pinnavaia Thomas J. 
Published: May 2005

A fundamental advance in the intercalation chemistry of claysis the formation for the first time of smectite clay heterostructures with regularly stratified organic and inorganic exchange cations, e.g. the fluorohectorite heterostructure with gallery cations Na⊕ and C16H33PBushown in the figure. Their transformation into rectorite‐like alumina pillared analogues is also demonstrated.magnified image
Decoration of carbon nanotubes
Authors: Ebbesen Thomas W. , Hiura Hidefumi , Bisher Margaret E. , Treacy Michael M. J. , Shreeve‐Keyer Julie L. , Haushalter Robert C. 
Published: May 2005

Applications of carbon nanotubes, a unique material, are limited by the relative inertness of the carbon surface. A general method of overcoming this is proposed in which the surface is preoxidized, producing various groups on the surface. These surface groups then act as nucleation points. For example, in the electroless plating reaction the surface of the nanotubes becomes decorated with silver particles (see figure). magnified image
Stabilization of amorphous calcium carbonate by specialized macromolecules in biological and synthetic precipitates
Authors: Aizenberg Joanna , Addadi Lia , Weiner Stephen , Lambert Gretchen 
Published: May 2005

Composite structures in which amorphous and crystalline phases coexist are formed by some organisms. The spicules of the sponge Clathrina are shown to be composed of a crystalline calcitic core and an outer layer of amorphous CaCO3 (see figure). The latter material, normally a highly unstable mineral, is stabilized in vitro by macromolecules extracted from the outer sponge spicule layer. The combination of crystalline and stabilized amorphous phases may have important implications for materials applications. magnified image
Nanocrystal gold molecules
Authors: Whetten Robert L. , Khoury Joseph T. , Alvarez Marcos M. , Murthy Srihari , Vezmar Igor , Wang Z. L. , Stephens Peter W. , Cleveland Charles L. , Luedtke W. D. , Landman Uzi 
Published: May 2005

Gold nanocrystals passivated by self‐assembled monolayers of straightchain alkylhiolate molecules have been obtained as highly purified molecular materials of high intrinsic stability. Evidence is presented for a predicted discrete sequence of energetically optimal fcc structures of a truncated octahedral morphological motif (see cover). The nanocrystal materials have a propensity to form extended superlattics, such as that in the Figure. magnified image
Molecular recognition by self‐assembled monolayers detected with surface plasmon resonance
Authors: Huisman Bart‐Hendrik , Kooyman Rob P. H. , van Veggel Frank C. J. M. , Reinhoudt David N. 
Published: May 2005

Self‐assembled monolayers containing cavitand recognition sites have been used for the first time as an interface for vapor detection using surface plasmon resonance (SPR). Fast response times (t90% < 1 s) and high sensitivity for tetrachloroethylene over other chlorinated hydrocarbons were measured with a monolayer of the resorcin[4]arene cavitand adsorbate shown in the Figure. magnified image
New twin liquid crystalline diazole derivatives
Authors: Sato Moriyuki , Ujiie Seiji 
Published: May 2005

Twin liquid crystalline diazole derivatives are expected to have a higher potential for liquid crystal (LC) formation than the corresponding non‐twin derivatives. The preparation of twin 1,3,4‐thiadiazole and 1,3,4‐oxadiazole derivatives is described and the investigation of their LC properties reported. A characteristic nematic schlieren texture of one of the oxadiazoles is shown in the Figure. magnified image
Surface modification and patterning of conjugated polymers with near‐field optical microscopy
Authors: Wei P. K. , Hsu J. H. , Hsieh B. R. , Fann W. S. 
Published: May 2005

Near‐field scanning optical microscopy (NSOM) has been used to write and read images on a conjugated polymer film—such as that in the Figure–with a resolution of ∼ 0.1 μm, clearly breaking the diffraction limit. It is demonstrated that photo‐oxidation processes produce the contrast and that NSOM has the potential to control the photochemistry of a conjugated polymer at the nanometer scale. magnified image
Electroactive films with a polyrotaxane organic backbone
Authors: Kern Jean‐Marc , Sauvage Jean‐Pierre , Bidan Gérard , Billon Martial , Divisia‐Blohorn Bernadette 
Published: May 2005

Polyrotaxane‐like structures consisting of macrocycles trapped to form a polymeric network (see Figure) have been synthesized using a pre‐assembling principle. The synthesis and electrochemical characterization of thin films are described. In addition to the classical properties of organic conducting polymers, the assemblies exhibit very specific properties arising from the coordinating macrocycles sliding between the nodes of the network. magnified image
Efficient blue light emitting devices based on rigid‐rod polyelectrolytes
Authors: Cimrová Vera , Schmidt Wolfgang , Rulkens Rudy , Schulze Margit , Meyer Wolfgang , Neher Dieter 
Published: May 2005

Blue light emitting devices based on a rigid‐rod polyelectrolyte–sulfonated poly(p‐phenylene), see Figure–that has both luminescent and ionic moieties have been prepared and their properties investigated. It is reported that the devices exhibited a low onset voltage (3.3 V), the external quantum efficiencies reached 0.8%, and the size of the counter ion had a pronounced influence on the electrical characteristics. magnified image
Nanometer‐size Cu clusters formed by reversible deintercalation on layered chalcogenides with scanning probe techniques
Authors: Jaegermann Wolfram , Jiang Lei , Iyoda Tomakazu , Tomm Yvonnne , Pettenkofer Christian , Hashimoto Kazuhito , Fujishima Akira 
Published: May 2005

Modification of surfaces by scanning probe techniques is the key to future nanotechnologies. In the novel approach described here, the reversible deintercalation of Cu from (0001) surfaces of 1T TaSe2 by means of the atomic force microscope can produce large Cu clusters, such as that in the Figure, that can be reintercalated. A mechanism is proposed for the intercalation and tip‐induced deintercalation. magnified image
Growth of silicalite films on pre‐assembled layers of nanoscale seed crystals on piezoelectric chemical sensors
Authors: Bein Thomas , Mo Shangyi , Mintova Svetlana , Valtchev Valentin , Schoeman Brian , Sterte Johan 
Published: May 2005

Zeolite‐modified quartz crystal microbalances are demonstrated to have excellent characteristics as chemical sensors. The Figure illustrates the synthetic strategy used to form the zeolite film on the electrode: the gold electrode (left) is covered with a partially crosslinked surface of siloxy groups, to which a cationic polymer is attached. The colloidal silicalite‐1 crystals (blocks) act as seeds for the growth of an oriented silicalite layer. magnified image