Synthesis of thiacalix[4]arene task-specific ionic liquids

<p>The preparative methods for the synthesis of imidazolium and pyridinium room temperature task-specific ionic liquids possessing thiacalix[4]arene complexing groups in cationic or anionic fragments of the molecule are described. The cationic imidazolium and pyridinium derivatives of tetrabuthoxythiacalixarene existing in the conformation 1,3-alternate are capable to bind “soft” metal cations due to cooperative cation-π and ion–dipole interactions with spatially contiguous benzene rings and oxygen atoms of the thiacalixarene platform. The cone-shaped imidazolium salts of the tetrahydroxythiacalix[4]arene sulfonic acid can chelate cations of transition metals, lanthanides, and actinides by oxygen and sulfur atoms at the lower rim of macrocycle.</p

Dibutylphosphinoylmethyloxythiacalix[4]arenes. Synthesis, structure, americium, europium and technetium extraction

<div><p>A series of thiacalix[4]arenes bearing one, two or four chelating dibutylphopshinoylmethoxy groups have been synthesised and studied in the context of this paper. The synthesis consisted of precise Williamson alkylation of thiacalixarene tetrols with tosylate of dibutylhydroxymethyl phosphine oxide in the presence of alkali metal carbonates or sodium hydride. Stereochemical yield of the reaction (<i>cone</i> or 1,3-<i>alternate</i> conformer) depends on the nature of alkali metal. Small-sized ‘hard’ sodium cation organises the macrocyclic platform in the <i>cone</i> conformation, but larger and ‘soft’ potassium and cesium cations stabilise the macrocycle in the <i>1,3</i>-<i>alternate</i> conformation. All synthesised compounds (except monophosphine monoxide) possess either moderate or high extraction ability towards pertechnetate ion. The <i>cone</i>-shaped thiacalix[4]arene tetraphosphine tetraoxide due to cooperative (macrocyclic) effect of eight oxygen atoms of the phosphinoylmetoxy-binding groups effectively extract spherical americium, europium cations due to cooperative (macrocyclic) effect of eight oxygen atoms of the phosphinoylmetoxy-binding groups. The extraction ability is very similar to that of calix[5]arene pentaphosphine pentaoxide existing in the <i>cone</i> conformation.</p></div