Alkyl Ammonium Ion Selectivity of Hexahomotrioxacalix[3]arene Triamide Derivative having the Intramolecular Hydrogen-Bonding Group

The lower rim functionalized hexahomotrioxacalix[3]arene triamide 4 with cone-conformation was synthesized from triol 1 by a stepwise reaction. The different extractability for alkali metal ions, transition metal ions, and alkyl ammonium ions from water into dichloromethane is discussed. Due to the strong intramolecular hydrogen bonding between the neighboring NH and CO groups in triamide 4, its affinity to metal cations was weakened. Triamide 4 shows a single selectivity to n-BuNH ₃ ⁺ . The anion complexation of triamide 4 was also studied by ¹H NMR titration experiments. Triamide 4 binds halides through the intermolecular hydrogen bonding among the NH hydrogens of amide in a 1:1 fashion in CDCl₃. The association constants calculated from these changes in chemical shifts of the amide protons are K _a = 223 M^?1 for Cl^? and K _a = 71.7 M^?1 for Br^?. Triamide 4 shows a preference for Cl^? complexation than Br^? complexation.     

Studies of tetracene- and pentacene-based organic thin-film transistors fabricated by the neutral cluster beam deposition method

The neutral cluster beam deposition (NCBD) method has been applied to produce and characterize organic thin-film transistors (OTFTs) based upon tetracene and pentacene molecules as active layers. Organic thin films were prepared by the NCBD method on hexamethyldisilazane (HMDS)-untreated and -pretreated silicon dioxide (SiO2) substrates at room temperature. The surface morphology and structures for the tetracene and pentacene thin films were examined by atomic force microscopy (AFM) and X-ray diffraction (XRD). The measurements demonstrate that the weakly bound and highly directional neutral cluster beams are efficient in producing high-quality single-crystalline thin films with uniform, smooth surfaces and that SiO2 surface treatment with HMDS enhances the crystallinity of the pentacene thin-film phase. Tetracene- and pentacene-based OTFTs with the top-contact structure showed typical source-drain current modulation behavior with different gate voltages. Device parameters such as hole carrier mobility, current on/off ratio, threshold voltage, and subthreshold slope have been derived from the current-voltage characteristics together with the effects of surface treatment with HMDS. In particular, the high field-effect room-temperature mobilities for the HMDS-untreated OTFTs are found to be comparable to the most widely reported values for the respective untreated tetracene and pentacene thin-film transistors. The device performance strongly correlates with the surface morphology, and the structural properties of the organic thin films are discussed.     

An ultraviolet-curable mold for sub-100-nm lithography

We describe a novel UV-curable mold that is stiff enough for replicating dense sub-100-nm features even with a high aspect ratio. It also allows for flexibility when the mold is prepared on a flexible support such that large area replication can be accomplished. The composite material of the mold is inert to chemicals and solvents. The surface energy is made low with a small amount of releasing agent such that the mold can be removed easily and cleanly after patterning. In addition, the material allows self-replication of the mold. These unique features of the mold material should make the mold quite useful for various patterning purposes.     

Regioselective synthesis of pentasubstituted benzene derivatives: TBAF as an effective catalyst for the sequential Michael addition-intramolecular aldolization

Polysubstituted benzene derivatives were synthesized starting from the Baylis-Hillman adducts via the sequential introduction of primary nitroalkane at the primary position, Michael addition to β-branched Michael acceptor, aldol condensation, elimination of nitrous acid, and the final aromatization process.     

Bioconversion of cellulose into ethanol by nonisothermal simultaneous saccharification and fermentation

The kinetic characteristics of cellulase and beta-glucosidase during hydrolysis were determined. The kinetic parameters were found to reproduce experimental data satisfactorily and could be used in a simultaneous saccharification and fermentation (SSF) system by coupling with a fermentation model. The effects of temperature on yeast growth and ethanol production were investigated in batch cultures. In the range of 35-45 degrees C, using a mathematical model and a computer simulation package, the kinetic parameters at each temperature were estimated. The appropriate forms of the model equation for the SSF considering the effects of temperature were developed, and the temperature profile for maximizing the ethanol production was also obtained. Briefly, the optimum temperature profile began at a low temperature of 35 degrees C, which allows the propagation of cells. Up to 10 h, the operating temperature increased rapidly to 39 degrees C, and then decreased slowly to 36 degrees C. In this nonisothermal SSF system with the above temperature profile, a maximum ethanol production of 14.87 g/L was obtained.     

Supramolecular conducting microfibers from amphiphilic tetrathiafulvalene-based organogelator

An amphiphilic tetrathiafulvalene molecule can gelate a variety of organic solvents in view of multiple intermolecular interactions, especially in polar solvent with the formation of highly-ordered columnar structures. The formation of mixed-valence states shows the semiconductive behaviors with the conductivity of 10^-4 S/cm, as promising candidates for organic electronics.