Conductive and superhydrophobic ram-butan-like hollow spheres of polyanilineare formed through self-assembly byusing perfluorooctane sulfonic acid as adopant, soft template, and superhydro-phobic agent at the same time, asreported by Meixiang Wan and LeiJiang on p. 2092. The results show thatthe approach used is not only simple,but also that the hollow spheres have alarge specific area and exhibit physicalproperties that are required for manyapplications in nanotechnology.
Inside Cover:
The background scanning electronmicroscopy image shows nanometricpatterns of the 3D spin crossovercoordination polymer Fe(pyra-zine)[Pt(CN)4] (see schematic structurein the circle), which have been fabri-cated using a combination of lift-off andmultilayer sequential assembly meth-ods. These patterns, reported by GáborMolnár, Azzedine Bousseksou, andco-workers on p. 2163, exhibit a bistabil-ity of their electronic states (1A1�
5T2),and thus represent a novel platform fora wide array of potential applications.
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Look for the following Advances in Advance onlinein Wiley InterScience. You can find them atwww.advmat.de under Special Features.
T. Yu, Y. H. Deng, L. Wang, R. L. Liu,L. J. Zhang, B. Tu, D. Y. Zhao*Ordered Mesoporous NanocrystallineTitanium-Carbide/CarbonComposites from In SituCarbothermal ReductionPublished Online: July 26, 2007DOI: 10.1002/adma.200700667
Y. Lee, S.-H. Park, K.-B. Kim,J.-K. Lee*Fabrication of Hierarchical Structureson a Polymer Surface to MimicNatural Superhydrophobic SurfacesPublished Online: August 2, 2007DOI: 10.1002/adma.200700820
G. Derrien, J. Hassoun, S. Panero,B. Scrosati*Nanostructured Sn–C Compositeas an Advanced Anode Materialin High-Performance Lithium-IonBatteriesPublished Online: August 2, 2007DOI: 10.1002/adma.200700748
F. Cordella,* F. Quochi, M. Saba,A. Andreev, H. Sitter, N. S. Sariciftci,A. Mura, G. BongiovanniOptical Gain Performance of Epitaxi-ally Grown para-Sexiphenyl FilmsPublished Online: July 27, 2007DOI: 10.1002/adma.200701041
All our articles are available onlinein advance of print. The articleslisted here have been judged by thereferees or the editor to be eithervery important or very urgent andwere immediately copyedited,proofread, and published online whenthe manuscript arrived in the editorialoffice in its final form. As long asthere is no page number available,online manuscripts should be citedin the following manner:
J. Roncali,* P. Leriche,A. Cravino ......................... 2045 – 2060
From One- to Three-DimensionalOrganic Semiconductors: In Searchof the Organic Silicon?
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The anisotropic electronic propertiesof organic semiconductors based on 1Dp-conjugated systems implies a controlof molecular orientation that can posespecific problems for the fabrication of(opto)electronic devices by solutionprocesses. This Review discussesemerging alternative strategies involv-ing the development of organic semi-conductors derived from 3D conjugatedarchitectures and capable of exhibitingisotropic electronic properties.
COMMUNICATIONSOrganic Light-Emitting Diodes
B. D. Chin,* C. Lee ........... 2061 – 2066
Confinement of Charge Carriers andExcitons in ElectrophosphorescentDevices: Mechanism of Light Emissionand Degradation
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Charge-carrier and exciton confinementis essential for efficiency and stabilityenhancment of electrophosphorescentdevices. Emission-layer lifetimes of a4,4′-N,N′-dicarbazole-biphenyl hostdoped with either a red- or green-emitting dye (upper and lower figures)show a strong dependence and nearindependence, respectively, on the typeof exciton blocking layer used (four areshown). This is explained using energy-level differences and correspondingcharge-trapping behavior.
S. Furumi,* H. Fudouzi,H. T. Miyazaki,Y. Sakka ............................. 2067 – 2072
Flexible Polymer Colloidal-CrystalLasers with a Light-Emitting PlanarDefect
Flexible polymer laser devices excitedby low-threshold optical light arefabricated from colloidal crystals (CCs;see figure). The laser-cavity structureconsists of a light-emitting layer sand-wiched between two polymer CC films.Optical excitation with a green beambrings about emission with a red beam.This process allows the production ofultralightweight, low-cost, flexible, andeasily processible all-plastic lasers.
Hybrid Materials
S. Meuer, P. Oberle, P. Theato,W. Tremel, R. Zentel* ...... 2073 – 2078
A general approach for the functional-ization of inorganic nanoparticles withpolymers is presented. The polymersfor functionalization are designed topossess an anchor block and a solubleblock. By this approach, TiO2 nanorodscan be solubilized up to high concentra-tions in organic media. Owing to theiranisotropic shape, liquid crystallinephases are formed, opening the possib-lity of orienting the nanorods macro-scopically.
Thin Films
T. Siegrist,* C. Besnard, S. Haas,M. Schiltz, P. Pattison, D. Chernyshov,B. Batlogg, C. Kloc ........... 2079 – 2082
A Polymorph Lost and Found: TheHigh-Temperature Crystal Structureof Pentacene
A well-defined structural phasetransformation is observed in bulksingle crystals of pentacene, whereaspentacene powders heated above thephase-transformation temperature donot always fully convert, and uponcooling, coexistence of the two poly-morphs is observed down to roomtemperature. The first-order phasetransformation is isostructural: theclose-packed herringbone-type layersshift against each other, keeping thesame symmetry.
Photocatalysis
L. Z. Zhang,* I. Djerdj,M. Cao, M. Antonietti,M. Niederberger* .............. 2083 – 2086
Nonaqueous Sol–Gel Synthesisof a Nanocrystalline InNbO4
Visible-Light Photocatalyst
InNbO4 nanoparticles characterizedby high crystallinity and particle sizesin the range of 10–30 nm (see TEMimage) are synthesized by a soft-chem-istry route involving the solvothermalreaction of indium acetylacetonate andniobium chloride in benzyl alcohol at200 °C. The as-synthesized nanopow-ders offer a high photocatalytic activityunder illumination with visible light.
Superior Electrode Performanceof Nanostructured MesoporousTiO2 (Anatase) through EfficientHierarchical Mixed ConductingNetworks
An optimized nanostructure design ofelectrode material for high power, highenergy lithium batteries is realized.Highly Li-permeable materials areobtained by introducing hierarchicalmixed conducting networks on bothnanoscale and microscale levels(see figure). A mesoporous TiO2:RuO2
composite is selected as an exampleof this new design.
Hollow Microspheres
Y. Zhu, D. Hu, M. X. Wan,* L. Jiang,*Y. Wei ................................. 2092 – 2096
Conducting and SuperhydrophobicRambutan-like Hollow Spheresof Polyaniline
Superhydrophobic polyaniline (PANI)hollow spheres (see figure and cover)with high conductivity were self-as-sembled by using perfluorooctane sulfu-ric acid (PFOSA) as both dopant andsoft template. It is proposed that thesespheres are formed by a co-operativeeffect of two self-assembly processes:spherical micelles composed of PFOSAserve as a “microreactor” and PFOS/aniline salt micelles act as the softtemplate of the PANI nanofibers.
Organic Electronics
A. K. Tripathi, M. Heinrich,T. Siegrist, J. Pflaum* ....... 2097 – 2101
Growth and Electronic Transportin 9,10-Diphenylanthracene SingleCrystals—An Organic Semiconductorof High Electron and Hole Mobility
10 1001
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HL-model (Et = 100 meV)
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Electron and hole transport is demon-strated on bulk crystals of the organicsemiconductor 9,10-diphenylanthracene(DPA). The high mobilities at roomtemperature for electrons (ca. 13 cm2
Vs–1) and holes (ca. 3.7 cm2 Vs–1) makeDPA a prominent candidate for deviceapplications. The hole mobility followsa bandlike transport at high tempera-tures (200K–400K) and a saturationbehavior in the low-temperature regime(see figure), the latter being discussedin the context of various transportmodels.
Alloys
Y. H. He, Y. Jiang, N. P. Xu,J. Zou,* B. Y. Huang, C. T. Liu,P. K. Liaw ........................... 2102 – 2106
Fabrication of Ti–Al Micro/Nanometer-Sized Porous Alloysthrough the Kirkendall Effect
A new method based on the Kirkendalleffect is developed to fabricate Ti–Alporous alloys with open pores andadjustable pore size. This novel porousmaterial (microstructures shown in thefigure) has excellent pore size stabilityand outstanding corrosion and oxida-tion resistance. These exceptionaladvantages of fabricated Ti–Al porousalloys make them an ideal filtrationcandidate for rugged environments.
M.-Y. Jeong, H. M. Kim,S.-J. Jeon, S. Brasselet,*B. R. Cho* ......................... 2107 – 2111
Octupolar Films with SignificantSecond-Harmonic Generation
Octupolar films containing 1,3,5-tricyano-2,4,6-tris(p-diethylaminostyryl)benzene ina polymethylmetacrylate matrix are prepared by using free-casting and spin-coatingmethods and their physical properties are characterized by using polarization mi-croscopy, X-ray diffraction spectra, and second-harmonic generation (see figure).The films exhibit an optimum molecular packing that can find useful applications inelectro-optic devices.
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Nanowires
X. D. Han, K. Zheng,Y. F. Zhang, X. N. Zhang,Z. Zhang,* Z. L. Wang* ... 2112 – 2118
Low-Temperature In Situ Large-StrainPlasticity of Silicon Nanowires
The large-strain plasticity (LSP) ofsingle-crystalline silicon nanowires(Si NWs) observed in situ at roomtemperature by axial tension experi-ments carried out in an ultrahigh-reso-lution electron microscope is reported.The LSP is demonstrated to result in afourfold reduction in NW diameterbefore fracture (see figure), which isthree orders of magnitude higher thanthat of bulk Si.
Surface Patterning
W. Hu, N. Lu,* H. Zhang,Y. Wang, N. Kehagias, V. Reboud,C. M. Sotomayor Torres, J. Hao,W. Li, H. Fuchs, L. Chi* ... 2119 – 2123
Multicolor Emission on PrepatternedSubstrates Using a Single Dye Species
A new strategy for realizing patternedsurfaces with different emission colorsis demonstrated. This approach relieson the gas-phase deposition of dyemolecules onto solid substrates thatare prepatterned by nanoimprint litho-graphy (see figure). Only a singlemolecular species is involved. Thus, theobserved color change and correspond-ing spectral shift in the emission proper-ties depends on the substrate used andcan be tuned by surface engineering.
Surface Patterning
Y. Mei,* D. J. Thurmer,F. Cavallo, S. Kiravittaya,O. G. Schmidt .................... 2124 – 2128
Semiconductor micro-/nanochannel networks are developed by deterministic layerwrinkling and applied into a fluidics study. Both linear (see figure) and circularnanochannel networks, consisting of a main channel and several perpendicularlyoriented branch channels, are created, where the periodicity and position of thebranch channels can be tuned and controlled by changing the width of the partiallyreleased layers and by applying appropriate lithography.
Chromia/alumina catalysts are widelyused for oxidative dehydrogenationof alkanes, but questions about therelationship between their propertiesand characteristics remain. Experimen-tal techniques and first-principlescalculations are used to demonstratethat the reaction is enabled by CrOx
clusters adsorbed on alumina surfaces,and that the key reaction sites arelow-coordination-number O atoms (seefigure).
Perovskites
J. Martynczuk, M. Arnold, H. Wang,J. Caro, A. Feldhoff* ........ 2134 – 2140
How (Ba0.5Sr0.5)(Fe0.8Zn0.2)O3–d and(Ba0.5Sr0.5)(Co0.8Fe0.2)O3–d PerovskitesForm via an EDTA/Citric AcidComplexing Method
Perovskites with complex stoichiome-tries are widely synthesized by EDTA/citric acid complexing methods. Eventhough these methods are well estab-lished, details of the perovskite struc-ture formation remained hidden. Thestructure analysis of different stages ofthe synthesis process allows the identifi-cation of the crystalline intermediatesas spinel and carbonate. The perovskiteis formed between them in a nanoscalesolid-state reaction.
Nanostructures
L. Q. Xu, J. H. Zhan,*J. Q. Hu, Y. Bando, X. L. Yuan,T. Sekiguchi, M. Mitome,D. Golberg ......................... 2141 – 2144
High-Yield Synthesis of RhombohedralBoron Nitride Triangular Nanoplates
r-BN
Unique, highly crystalline, triangularBN nanoplates (see figure) with a widebandgap—which will ease their integra-tion into nanoelectronic and photonicdevices—are reported to be synthesizedby reaction of NH4BF4 and NaNH2
with the assistance of metallic Ni. Athorough analysis of the morphologicaland structural characteristics of thenanoplates is presented.
Sol–Gel Processes
S. Fireman-Shoresh, S. Marx,D. Avnir* ............................ 2145 – 2150
Enantioselective Sol–Gel MaterialsObtained by Either Dopingor Imprinting with a Chiral Surfactant
OSi
OSi
OSi
O
Si
O Si
O-
O-
O
+
+
Chiral pores are fabricated in pheny-lated sol–gel materials using chiralsurfactants (see figure). The interac-tions between the pores with andwithout the surfactant and chiralmolecular probes are investigated.The effect of entrapped and extractedsurfactant changes the enantiose-lectivity of the material.
E. J. García,* A. J. Hart, B. L. Wardle,A. H. Slocum ..................... 2151 – 2156
Fabrication and NanocompressionTesting of Aligned Carbon-Nanotube–Polymer Nanocomposites
20 µm
The reinforcement of fiber–polymercomposites with arrays of alignedcarbon nanotubes (CNTs) is reported.Nanocomposite features containingvertically aligned CNTs and a commer-cially available polymer are fabricatedand mechanically characterized with adirect nanocompression method using aflat punch mounted on a nanoindenter(see figure). The results show areinforcement of 220 % at a CNTvolume fraction of 2 %.
Surface Patterning
R. Ruiz,* N. Ruiz, Y. Zhang,R. L. Sandstrom,*C. T. Black ......................... 2157 – 2162
Local Defectivity Control of 2DSelf-Assembled Block CopolymerPatterns
Surface patterning of copolymers viaself-assembly is achieved by substratedesign. The figure shows a polystyrene-block-poly(methyl methacrylate)symmetric diblock copolymer confinedin a tapered structure. Engineeringthe channel structure provides localdefectivity control for defect-freestriped lamellar patterns at thenanometer scale.
Nanopatterning
G. Molnár,* S. Cobo, J. A. Real,F. Carcenac, E. Daran, C. Vieu,A. Bousseksou* ................. 2163 – 2167
A Combined Top-Down/Bottom-UpApproach for the Nanoscale Patterningof Spin-Crossover CoordinationPolymers
Micro- and nanometer-sized patternsof the spin-crossover compoundFe(pyrazine)[Pt(CN)4] have beenfabricated using a combination oflift-off and multilayer sequential assem-bly methods. These patterns (see figureand inside cover) exhibit a bistabilityof their electronic states and, thus,represent a novel platform for a widearray of potential applications.
Organic Electronics
H. Wang, F. Zhu, J. Yang, Y. Geng,D. Yan* .............................. 2168 – 2171
Weak Epitaxy Growth AffordingHigh-Mobility Thin Films of Disk-LikeOrganic Semiconductors
Thin films of phthalocyaninecompounds show weak epitaxial growthon a monodomain film of a rod-likemolecule (see figure). The resultingorganic electronic devices exhibit highcharge carrier mobilities close to thoseof the single-crystal devices.
Tunable fabrication of noble-metal hollow nanoparticle chains (HNPCs) is achievedby a strategy that exploits the variation of an external applied magnetic field duringsynthesis (see figure). The magnitude of the field has a strong effect on the nano-particles assembly, ranging from disperse to chainlike. The length and the opticalproperties of the HNPCs can be tuned, and such a synthesis may provide enhancedfunctionality for applications such as drug delivery or catalysis.
