/pdf/self-assembled-monolayers-of-thiolates-on-metals-as-a-form-1neb0hj3k4.pdf

Self-assembled monolayers of thiolates on metals as a form of nanotechnology.

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

We have used the pH-induced self-assembly of a peptide-amphiphile to make a nanostructured fibrous scaffold reminiscent of extracellular matrix. The design of this peptide-amphiphile allows the nanofibers to be reversibly cross-linked to enhance or decrease their structural integrity. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes of hydroxyapatite are aligned with the long axes of the fibers. This alignment is the same as that observed between collagen fibrils and hydroxyapatite crystals in bone.

http://science.sciencemag.org/content/sci/294/5547/1684.full.pdf

Self-assembly and mineralization of peptide-amphiphile nanofibers

Since the discovery of highly conducting polyacetylene by Shirakawa, MacDiarmid, and Heeger in 1977, π-conjugated systems have attracted much attention as futuristic materials for the development and production of the next generation of electronics, that is, organic electronics. Conceptually, organic electronics are quite different from conventional inorganic solid state electronics because the structural versatility of organic semiconductors allows for the incorporation of functionality by molecular design. This versatility leads to a new era in the design of electronic devices. To date, the great number of π-conjugated semiconducting materials that have either been discovered or synthesized generate an exciting library of π-conjugated systems for use in organic electronics. 11 However, some key challenges for further advancement remain: the low mobility and stability of organic semiconductors, the lack of knowledge regarding structure property relationships for understanding the fundamental chemical aspects behind the structural design, and realization of desired properties. Organic field-effect transistors (OFETs) are a kind of device consisting of an organic semiconducting layer, a gate insulator layer, and three terminals (drain, source, and gate electrodes). OFETs are not only essential building blocks for the next generation of cheap and flexible organic circuits, but they also provide an important insight into the charge transport of πconjugated systems. Therefore, they act as strong tools for the exploration of the structure property relationships of πconjugated systems, such as parameters of field-effect mobility (μ, the drift velocity of carriers under unit electric field), current on/off ratio (the ratio of the maximum on-state current to the minimum off-state current), and threshold voltage (the minimum gate voltage that is required to turn on the transistor). 17 Since the discovery of OFETs in the 1980s, they have attracted much attention. Research onOFETs includes the discovery, design, and synthesis of π-conjugated systems for OFETs, device optimization, development of applications in radio frequency identification (RFID) tags, flexible displays, electronic papers, sensors, and so forth. It is beyond the scope of this review to cover all aspects of π-conjugated systems; hence, our focus will be on the performance analysis of π-conjugated systems in OFETs. This should make it possible to extract information regarding the fundamental merit of semiconducting π-conjugated materials and capture what is needed for newmaterials and what is the synthesis orientation of newπ-conjugated systems. In fact, for a new science with many practical applications, the field of organic electronics is progressing extremely rapidly. For example, using “organic field effect transistor” or “organic field effect transistors” as the query keywords to search the Web of Science citation database, it is possible to show the distribution of papers over recent years as shown in Figure 1A. It is very clear

Semiconducting π-conjugated systems in field-effect transistors: a material odyssey of organic electronics.

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Nucleation process of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) on three kinds of alkali halides is quantitatively studied by use of atomic force microscope (AFM). The sizes of the smallest nuclei observed for the TTF-TCNQ film grown on alkali halides at the substrate temperature of 20°C and the molecular flux of 1 × 1018 [molecules/m2 .s] were larger than several 10 nm. The deposition time of several ten seconds were necessary for the generation of these nuclei and that depended on the kind of substrates. The reasons why such a long period for the growth of the nuclei is necessary are discussed on basis of AFM observation.

Nucleation mechanism of TTF-TCNQ on alkali halides

Photoresponsive organic light-emitting devices (OLEDs) combining OLED with a photoconductive layer were fabricated By irradiating external light to the devices, intensity of electroluminescent emission can be controlled Highly efficient photoresponsive OLEDs using Ir complexes as phosphorescent materials were realized

http://ieeexplore.ieee.org/iel5/10492/33247/01569512.pdf

Organic Light-emitting Devices with Photoresponsive Layer

We prepared a highly oriented thin film of the simplest polysilane, poly(dimethylsilylene) (PDMS) by friction transfer method. It had an ability of aligning liquid crystals. A liquid crystal, 4-cyano-4′-n-pentylbiphenyl (5CB) sandwiched between oriented PDMS layers was uniformly oriented. The molecular axis of 5CB lay in parallel to the direction of PDMS chains. PDMS films could be easily photooxidized by UV light irradiation. 5CB between UV-irradiated PDMS oriented in the different manner from that between non-irradiated PDMS. The PDMS orienting films could be patterned by irradiation with a shadow mask and the orientation of 5CB induced by them was patterned.

Orientation Patterning of Liquid Crystals by UV-Irradiated Polysilane Oriented Films

Oligomeric dimethylsilane (ODMS) and 1,6-di-(p-methoxy-strtyl)benzene (DSB-1) grew epitaxially on the friction-transferred polydimethylsilane (PDMS) and poly(p-phenylenevinylene) (PPV) layers. The ODMS/PDMS and DSB-1/PPV double layers indicated the remarkable anisotropic feature in absorption and emission properties.

Fabrication, Characterization and Optical Properties of Epitaxially Grown Oligomer/polymer Double Layers

Electrical and optical properties of a potassium (K) -doped film of a hexadecyl chain-linked C 60 ( C60-C16 ) were evaluated by electric conductivity, UV-visible near-IR and Raman spectra. The conductivity of the pristine film (3×10 −7 S cm −1 ) largely increased to 0.1 S cm −1 after doping. The absorption band of C60-C16 anion was observed around 900 nm in the K-doped film. As a result of Raman spectra measurement, it was confirmed that tri- and/or tetra-anions of C60-C16 are formed in the film.

Kiyoshi Yase

Papers

Nucleation mechanism of TTF-TCNQ on alkali halides

Organic Light-emitting Devices with Photoresponsive Layer

Orientation Patterning of Liquid Crystals by UV-Irradiated Polysilane Oriented Films

Fabrication, Characterization and Optical Properties of Epitaxially Grown Oligomer/polymer Double Layers

Electrical and Optical Properties of a Potassium- doped Film of a Long Alkyl Chain-linked C 60