Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

The conductance of a single molecule connected to two gold electrodes was determined by repeatedly forming thousands of gold-molecule-gold junctions. Conductance histograms revealed well-defined peaks at integer multiples of a fundamental conductance value, which was used to identify the conductance of a single molecule. The resistances near zero bias were 10.5 +/- 0.5, 51 +/- 5, 630 +/- 50, and 1.3 +/- 0.1 megohms for hexanedithiol, octanedithiol, decanedithiol, and 4,4' bipyridine, respectively. The tunneling decay constant (betaN) for N-alkanedithiols was 1.0 +/- 0.1 per carbon atom and was weakly dependent on the applied bias. The resistance and betaN values are consistent with first-principles calculations.

http://science.sciencemag.org/content/sci/301/5637/1221.full.pdf

Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

High-throughput computational materials design is an emerging area of materials science. By combining advanced thermodynamic and electronic-structure methods with intelligent data mining and database construction, and exploiting the power of current supercomputer architectures, scientists generate, manage and analyse enormous data repositories for the discovery of novel materials. In this Review we provide a current snapshot of this rapidly evolving field, and highlight the challenges and opportunities that lie ahead.

The high-throughput highway to computational materials design

Multilayer thin films have garnered intense scientific interest due to their potential application in diverse fields such as catalysis, optics, energy, membranes, and biomedicine Here we review the current technologies for multilayer thin-film deposition using layer-by-layer assembly, and we discuss the different properties and applications arising from the technologies We highlight five distinct routes of assembly—immersive, spin, spray, electromagnetic, and fluidic assembly—each of which offers material and processing advantages for assembling layer-by-layer films Each technology encompasses numerous innovations for automating and improving layering, which is important for research and industrial applications Furthermore, we discuss how judicious choice of the assembly technology enables the engineering of thin films with tailor-made physicochemical properties, such as distinct-layer stratification, controlled roughness, and highly ordered packing

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Technology-driven layer-by-layer assembly of nanofilms

Magnetic luminescent nanocomposites were prepared via a layer-by-layer (LbL) assembly approach. The Fe3O4 magnetic nanoparticles of 8.5 nm were used as a template for the deposition of the CdTe quantum dots (QDs)/polyelectrolyte (PE) multilayers. The number of polyelectrolyte multilayers separating the nanoparticle layers and the number of QDs/polyelectrolyte deposition cycles were varied to obtain two kinds of magnetic luminescent nanocomposites, Fe3O4/PEn/CdTe and Fe3O4/(PE3/CdTe)n, respectively. The assembly processes were monitored through microelectrophoresis and UV−vis spectra. The topography and the size of the nanocomposites were studied by transmission electron microscopy. The LbL technique for fabricating magnetic luminescent nanocomposites has some advantages to tune their properties. It was found that the selection of a certain number of the inserted polyelectrolyte interlayers and the CdTe QDs loading on the nanocomposites could optimize the photoluminescence properties of the nanocomposites....

Fabrication of Magnetic Luminescent Nanocomposites by a Layer-by-Layer Self-assembly Approach

The conductance of carotenoid polyenes chemically bound at each end to gold contacts has been measured for single molecules containing 5, 7, 9, and 11 carbon-carbon double bonds in conjugation. The electronic decay constant, beta, is determined to be 0.22 +/- 0.04 A-1, in close agreement with the value obtained from first principles simulations (0.22 +/- 0.01 A-1). The absolute values of the molecular conductance are within a factor of 3 of those calculated from first principles. The small value of beta demonstrates that conductivity drops off only slowly with chain length, confirming that carotenoid conjugated chains are relatively good molecular "wires".

Electronic decay constant of carotenoid polyenes from single-molecule measurements.

We have studied the electronic changes caused by light-induced isomerization of a photochromic molecule between an open state (that absorbs in the UV to become closed) and a closed state (that absorbs in the visible to become open). Data obtained using a newly developed repetitive break junction method are interpreted in terms of single-molecule resistances of 526 +/- 90 M Omega in the open form and 4 +/- 1 M Omega in the closed form when the molecule is bound between two gold contacts via dithiol linkages. The corresponding ratio of open to closed resistance is in close agreement with the results of ab initio calculations, though the measured resistances are about half of the calculated values. Optical spectroscopy indicates that the photoisomerization occurs in both directions on small gold particles, evaporated thin gold films, and in the break junction experiments.

https://iopscience.iop.org/article/10.1088/0957-4484/16/6/012/pdf

Switching of a photochromic molecule on gold electrodes: single-molecule measurements

Single-walled carbon nanotubes (SWNTs) were covalently functionalized with biocompatible poly-l-lysine, which is useful in promoting cell adhesion. SWNTs played an important role as connectors to assemble these active amino groups of poly-l-lysine, which provided a relative “friendly” and “soft” environment for further derivation, such as attaching bioactive molecules. As an application example, by further linking peroxidase, an amplified biosensing toward H2O2 concerning this assembly was investigated.

Poly-l-lysine Functionalization of Single-Walled Carbon Nanotubes

Here we present a class of formaldehyde (HCHO) gas sensors with strong responses based on ordered mesostructured In2O3 nanorod arrays, which are synthesized via the nanocastiniz route by directly using the solvent-extracted mesoporous silica as a hard template. By choosing mesoporous silica with different pore sizes and interconnectivity as templates and varying the loading of indium resource on the silica template, we have obtained a series of mesostructured In2O3 nanorod arrays with different textural parameters such as specific surface area, pore size, nanorod diameter, etc. The gas sensing properties for formaldehyde (HCHO) of the In2O3 specimens were examined. The results reveal those mesostructured In2O3 nanorod arrays possess much stronger responses to HCHO even at low concentrations than the bulk In2O3, and larger specific surface areas and pore sizes as well as smaller nanorod diameters would be beneficial for enhancing the sensing properties of In2O3.

Jun Li

Papers

Fabrication of Magnetic Luminescent Nanocomposites by a Layer-by-Layer Self-assembly Approach

Electronic decay constant of carotenoid polyenes from single-molecule measurements.

Switching of a photochromic molecule on gold electrodes: single-molecule measurements

Poly-l-lysine Functionalization of Single-Walled Carbon Nanotubes

Ordered Arrays of Bead-Chain-like In2O3 Nanorods and Their Enhanced Sensing Performance for Formaldehyde