A supramolecular polymer gel with dual-responsiveness constructed by crown ether based molecular recognition

A supramolecular polymer gel was prepared from self-assembly of a heteroditopic A–B monomer based on benzo[18]crown-6. Such a gel shows interesting gel–sol transitions in response to dual-stimuli owing to the dynamically reversible complexation between benzo[18]crown-6 and primary alkylammonium salt moieties.

Dielectric Spectroscopy of Solutions of Some Alkylammonium Salts in Chloroform and 1-Octanol

Dielectric loss spectra between 1 MHz and 36 GHz have been measured at 20°C for solutions of hexadecyl trimethylammonium bromide and chloride, tetrahexylammonium bromide and tetrabutylam-monium bromide in chloroform and 1-octanol (three solutes per solvent) at moderate and high concen-trations. The discussion is aimed at identifying relaxation processes involving ions. Describing the relax -ational part of the spectra (after subtraction of the conductivity contribution) by a sum of spectral com-ponents, the lowest frequency component can be attributed to the solute in all cases. Its concentration dependence is indicative of two ionic relaxation processes differing in physical nature. The solvent is partly involved in those processes; moreover a structure breaking effect is likely to occur in case of the alcoholic solvent. The results are also discussed in comparison with a molten alkylammonium salt and with solutions of this and of inorganic salts.

Synthesis of Glycosyl Cyanides by the Reaction of 1-S-Phosphorothioates of Carbohydrates with Trimethylsilyl Cyanide

A new procedure is described for the synthesis of α,β-glycosyl cyanides by the reaction of per-O-benzylated S-α-ᴅ-glycopyranosyl phosphorothioates with trimethylsilyl cyanide in the presence of Lewis acid. Starting S-glycosyl phosphorothioates are prepared, directly, from O-benzyl protected reducing D-hexopyranoses (gluco-, galacto-, manno-) and alkylammonium salt of phosphorothioic acid under Lewis acid catalysis.