Nanostructures formed by combination of nanotube and polymer chain

We have investigated polymeric supramolecular systems of inclusion complexes between molecular nanotube and polymer chains theoretically and experimentally. This system indicates inclusion-dissociation behavior much sharper than the inclusion complex between cyclic molecule and small compounds. And we propose some functional supramolecules utilizing the combination of the nanotube or nanoring and polymer chains such as insulated molecular wire and topological gel.     

Physical properties of sol-gel derived poly(Vinylidene Fluoride)/Silica hybrid

Poly(vinylidene fluoride) (PVDF) was incorporated in situ with silica by a sol-gel process involving tetraethoxysilane. The mechanical properties of these in situ hybrids were compared with those of PVDF composites mechanically blended with 14-nm diameter fumed silica particles. The ultimate strength of the in situ hybrids was higher than that of the blend composites, since fumed silica particles aggregate and act as mechanically weak points. The thermal analysis, dynamic viscoelastic properties, and dielectric properties were compared. The β-relaxation of PVDF caused by the glass transition was observed at around −40°C in the differential scanning calorimetry (DSC) and the mechanical tan δ curves and at −30°C in the dielectric loss factor (ϵ”) curve. The αc-relaxation due to the molecular motion in the crystalline phase occurred at 61°C in DSC curve, at 100°C in the tan δ curve, and at 80°C in the ϵ” curve. The peak positions of these relaxations did not change, but the peak intensities were decreased with the increase in silica content for both the in situ hybrids and blend composites. The activation energies for PVDF were calculated as 136 kJ/mol for the β-relaxation and 96 kJ/mol for the αc-relaxation. The result that these activation energies did not depend on silica content may indicate the weak interaction between PVDF and silica.     

Syntheses of 2‐alkylthio‐1,3‐thiazine derivatives from S‐alkyldithiocarbamates and α,β‐unsaturated ketones

Various 2‐alkylthio‐1,3‐thiazine derivatives were synthesized by the reactions of S‐alkylthiocarbamates with α,β‐unsaturated ketones in the presence of BF₃ · Et₂O. The thiazine was converted into two isomeric dehydrated products in the presence of a Lewis acid. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:377–379, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10055     

Complex Formation Between Poly(dimethylsilane) and Cyclodextrins

Poly(dimethylsilane)s form inclusion complexes with cyclodextrins in high selectivity to give crystalline compounds. β‐Cyclodextrin forms complexes with poly(dimethylsilane)s of low molecular weight only, γ‐cyclodextrin with poly(dimethylsilane)s of high molecular weight in high yield, and α‐cyclodextrin does not form complexes with poly(dimethylsilane) at all. Complexes were isolated and characterized by spectroscopic methods and X‐ray diffraction.     

Supported Noble Metal Catalysts and Adsorbents with Soft Lewis Acid Functions

Heterogeneous noble metal catalysts exhibit various functions. Although their redox functions have been extensively studied, we focused on their soft Lewis acid functions. Supported Au, Pt, and Pd catalysts electrophilically attack the π-electrons of soft bases such as alkynes, alkenes, and aromatic compounds to perform addition and substitution reactions. Hydroamination, intramolecular cyclization of alkynyl carboxylic acids, isomerization of allylic esters, vinyl exchange reactions, Wacker oxidation, and oxidative homocoupling of aromatics are introduced based on a discussion of the active species and reaction mechanisms. Furthermore, the adsorption of sulfur compounds, which are soft bases, onto the supported AuNPs is discussed. The adsorption and removal of 1,3-dimethyltrisulfane (DMTS), which is the compound responsible for the stale odor of “hine-ka” in alcoholic beverages, particularly Japanese sake, is described.