Synthesis of calix[4]arene-based dipodal receptors: Competitive solvent extraction and liquid bulk membrane transport for selective recovery of Cu2+

A series of new p-tert-butylcalix[4]arene-based dipodal receptors are synthesised in high yields. The calix[4]arene units of all the receptors have been found to be present in cone conformation. To optimise the good extraction ability and high transport rate, we synthesised the receptors that differ from each other in their end groups. These receptors extract Cu²⁺  ion selectively from the buffered aqueous medium containing a mixture of metal ions. The receptor bearing four sp³ nitrogens has by far the greater ability to extract Cu²⁺  than the other receptors. All these receptors were effectively used for Cu²⁺  ion transport from the aqueous buffered source phase to the aqueous receiving phase.

     

A competitive sensing system based on cyclobis(paraquat-p-phenylene) and a new β-cyclodextrin-tetrathiafulvalene derivative

We report the synthesis of 4,5-di(ethylthio)-4′-[6-deoxy-β-cyclodextrin-6-yl-aminocarbonyl]-tetrathiafulvalene (β-CD-DET-TTF) and its inclusion abilities towards cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺ ) and 1-naphthol. The structure of the synthesised compound has been established by mass spectrometry and ¹H NMR spectra combined with a theoretical MM3 and AM1 study. The sensor affords a charge transfer (CT) complex with the CBPQT⁴⁺  and is able to include 1-naphthol in the cyclodextrin cavity. The complexes were characterised experimentally by UV–vis spectroscopy and simulated by a MM3 docking procedure. The sensing ability of the β-CD-DET-TTF/CBPQT⁴⁺  complex towards 1-naphthol has been investigated by a competitive spectral method.

The synthesis and characterisation of a new water soluble β-CD-DET-TTF derivative able to formed a CT complex with the CBPQT⁴⁺  acceptor is reported. The water soluble CT complex β-CD-DET-TTF/CBPQT⁴⁺  could be used as an efficient sensor towards aromatic guests prone to give inclusion complexes with the CBPQT⁴⁺  ring.