Thermally switchable polyrotaxane as a model of stimuli-responsive supramolecules for nano-scale devices

A polyrotaxane consisting of many β-cyclodextrins (β-CDs) and a triblock copolymer of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) capped with bulky end-groups was synthesized as a model of stimuli-responsive supramolecules for nanoscale devices. The polyrotaxane was reversibly soluble-insoluble in water in response to temperature. This was achieved through the assembled and dispersed states of β-CDs along the block copolymer. It is considered that intermolecular hydrogen bondings of β-CDs, as well as the PEG segment length of the copoloymer, are predominant factors for regulating such thermally switchable behavior of the polyrotaxane.     

Syntheses of cyanoselenoamides and diselenoamides: Conversion into selenazoles and selenazines

Reactions of dicyano compounds with a potassium selenocarboxylate afforded the corresponding cyanoselenoamides and diselenoamides in good yields of experimentally determined ratios. The obtained cyanoselenoamides were allowed to react with potassium selenocarboxylate, again to afford the corresponding diselenoamides in higher yields. The cyanoselenoamides and diselenoamides were investigated as substrates for preparations of selenazoles and selenazines. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:106–110, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10111     

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     

Enzymatic synthesis of a soluble polyphenol derivative from 4,4′-biphenyldiol

Enzymatic oxidative polymerization of 4,4′-biphenyldiol was performed in an aqueous organic solvent using horseradish peroxidase as catalyst. In the polymerization using a mixture of 1,4-dioxane and phosphate buffer (pH 7.0) (80:20 vol-%) as solvent, the monomer was quantitatively consumed to give powdery polymeric materials in a high yield. The resulting polymer is soluble in polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and acetone. The molecular weight of the methylated product is 7.3 × 10³. The polymer exhibits high thermal stability under nitrogen.