Calixarenes

The cover picture shows the complexation of actinide metal ions by picolinamide-based calix[6]arenes. These ligands possess remarkable efficiency in the extraction of trivalent metal ions even at very high HNO3 concentration and fair selectivity for actinide ions over lanthanide ions, which is useful in the recycling of the spent nuclear fuel. The Partitioning and Transmutation (P&T) strategy would allow the long-lived minor actinides (Np, Am, Cm) in fast nuclear reactors to be separated and transmutated and would also allow the radiotoxicity in the ultimate waste to be minimized, making nuclear power plants more efficient and sustainable. Details are discussed in the article by M. Mariani, A. Casnati et al. on p. 2675 ff.

The authors report the first efficient synthesis of
para-tert-butylcalix[8]arene and -[9]arene via an exceptionally straightforward innovative protocol that takes place at ambient temperature, employing readily available tin(IV) chloride and s-trioxane.

The conversion of axially chiral tetraalkoxyresorcin[4]arenes
(cyclochiral resorcinarenes) into the related tetrakis(triflates)
in high yields is described; this provides an efficient source
of chiral materials for use in palladium-catalyzed transforma-
tions, including the reductive removal of triflate groups and
the synthesis of compounds that are formally derived from
3-aminophenol, providing axially chiral derivatives that are
nitrogen-substituted on the upper rim.

This paper describes a general method to change the surface property of the oleic acid stabilized silver nanoparticles and successful tranferring of the silver nanoparticles from the organic phase into the aqueous phase. By vigorous shaking of a biphasic mixture of the silver organosol protected with oleic acid and p-sulfonated calix[4]arene (pSC4) aqueous solution, it is believed that an inclusion complex is formed between oleic acid molecules and pSC4, and the protective layer of the silver nanoparticles shifts from hydrophobic to hydrophilic in nature, which drives the transfer of silver nanoparticles from the organic phase into the aqueous phase. The efficiency of the phase transfer to the aqueous solution depends on the initial pSC4 concentration. The pSC4-oleic acid inclusion complex stabilized nanoparticles can be stable for long periods of time in aqueous phase under ambient atmospheric conditions. The procedure of phase transfer has been independently verified by UV-vis, tr...

The preparation of optically pure (–)-3-[(2R)-2-methoxy-2-
phenylethoxy]phenol from resorcinol monobenzoate and its
conversion into diastereoisomeric tetraalkoxyresorcin[4]-
arenes together with proof of the absolute configurations of
the products is reported. The results of the study indicate that
diastereoselective ring closure of linear tetrameric intermediates
is controlled by the steric demand of the alkyl group in
the precursor 3-alkoxyphenol

Two thread-shaped cations, pyridinium nicotinamide and imidazolium, as their chloride and hexafluorophosphate salts, were studied with regards to complexation with hydrogen-bond-donating acyclic and macrocyclic ligands. In the latter case, the cations form pseudorotaxanes templated by the chloride anion but not hexafluorophosphate. This formation is a function of the coupling of ion-pairing between the cation and chloride anion and subsequent recognition of the anion by the macrocyclic diamide, which provides the driving force for interpenetration. We propose that this anion template principle is a general method for the construction of pseudorotaxanes and could be applied to other cationic threads, anions, and macrocyclic species.