Rearrangement of carbanions and of ylides derived from 4-thiacyclohexenyl systems

The rearrangement of the carbanion and of the ylide derived from 5,5-diphenyl-4-thiacyclohexene to (E)2,2-diphenyle-1-methylthiovynylcyclopropane is shown to depend on the presence of a stabilizing substituent at C-5. A non concerted mechanism is proposed for this rearrangement. The carbanions from the 4-thiacyclohexene and from the sulfone of the 5,5-diphenyl-4-thiacyclohexene are stable. The cycloaddition of an aromatic thioketone to butadiene has been extended to an aliphatic thioketone.     

Nuclear waste treatment by means of supported liquid membranes containing calixcrown compounds

Permeability variation with repeated caesium transport experiments has been chosen to measure the leaching of the supported liquid membrane by the contacting aqueous solutions. This allowed us to characterize the SLM stability. Whereas classical crown ethers such as the widely used 21C7 derivatives were revealed to be poorly efficient and poorly stable in SLMs, crown-6-calix[4]arene compounds in the so-called1,3-alternate configuration led to very stable (over 50 days), highly selective (concentration factor>100) and efficient (decontamination factor=20) SLMs, for the removal of caesium from high salinity and acidity media. These results were achieved by using proper organic diluents and introducing hydrophobic substituents in the frame of the calixarenes.This paper is dedicated to the commemorative issue on the 50th anniversary of calixarenes.     

Synthesis, conformational studies and inclusion properties of N-substituted tetrahomodiazacalix[4]arenes

A series of tetrahomodiazacalix[4]arenes (1–8) with different substituents (or substituted) at the upper rim and/or N-side arm has been synthesized with acceptable yields. The compounds were characterized by elemental analysis, IR, MS and NMR methods. In particular, 5 was shown by X-ray crystallography to adopt the cone conformation in the solid state. Two-phase picrate extraction showed that 2 and 6, bearing N-2-picolyl arms, are the best extractants. Of the cations tested, Ag(I) is the best extracted by almost all ligands and the extraction efficiency follows the order 2-picolyl > 3-picolyl > 4-picolyl.     

New preorganized calix[4]arenes. Part I. A doubly-crowned calix and a double-calixcrown derived from 4,6,10,12,16,18,22,24,25,26,27,28-Dodecamethyl-5,11,17,23-tetrahydroxycalix[4] arene

A doubly-crowned calix and a double-calixcrown derived from 4,6,10,12,16,18,22,24,25,26,27, 28-dodecamethyl-5,11,17, 23-tetrahydroxycalix[4]arene (1) have been prepared by reaction of appropriate oligoethylene glycol ditosylates with (1) in acetonitrile in the presence of potassium carbonate. A potassium template effect is observed during one of the double cyclizations.     

Solvent Extraction of Sodium and Potassium Ions by Dicarboxylated Calix[4]arenes

The extraction of sodium and potassium ions by 25,27-dicarboxymethyl-26,28-dimethoxy-5,11,17,23-tetra-tert-butyl calix[4]arene (L1H2) in chloroform shows the formation of MLIH and M2LI complexes (M = Na, K). In 1,2-dichloroethane, the MLIH species are formed in the acidic pH range, while only the Na2LI species is found at high pH values. The corresponding extraction equilibrium constants K11 (M) and K21 (M) have been evaluated and show a selectivity in favour of Na+ as compared to K+, whatever the nature of the complexes. In chloroform, this selectivity is much more pronounced considering the 2 : 1 complexes: K11(Na)/K11(K) K21(Na)/K21(K).The coexistence of 1 : 1 and 2 : 1 metal : ligand complexes is also shown in the extraction of sodium in 1,2-dichloroethane by the 25,27-dicarboxymethyl-26,28-dimethoxyethoxy-5,11,17,23-tetra-tertbutyl calix[4]arene (LIIH2), locked in the cone conformation.Structural data of the complexes are discussed on the basis of 1H-NMR spectra. In particular, for LIH2, a conformational change from cone to partial cone upon metal complexation has been evidenced for the complexes KLIH, K2LI and Na2LI.     

Thoughts about an article of Yamato and coll.

This highlight makes comments on recent article of Yamato and coll. as molecular machines.     

Calixarene-Based Dendrimers. A Timely Review

This timely review focuses on the synthesis of dendrimers from calix[4]arenes and thiacalix[4]arenes. Some interesting features of these calix-dendrimers are given.     

Mini-review: calixarene liquid crystals

Calixarene liquid crystals were important part among calixarene derivatives. The synthesis and mesomorphic properties of all kinds of calixarene liquid crystala have been discussed and reviewed. There are two methods to prepare calixarene liquid crystals. One way is to introduce the corresponding functional groups with long alkyl chains, which usually afford columnar liquid crystal with a rigid bowlic core. The organization of liquid crystals possesses interesting changes after the complexation of guests. Another way is to introduce triphenylene unit to obtain calixarenes bowlic column with triphenylene units as ancillary lateral columns or triphenylene column with calixarene units on ancillary side. Moreover, they showed interesting conversion between two kinds of liquid crystals before and after complexation with ions.     

Crystal Structure of C-(n-propyl)calix[4]resorcinarene and its Complex with Caffeine

Abstract

The crystal structures of the all-cis epimer of C-(n-propyl)calix[4]resorcinarene (1) and its caffeine complex are reported. 1 · CH₃CN · H₂O (2) crystallizes in the tetragonal space group P4, a = 14.3645(9), c = 9.3344(8) Å, V = 1926(2) ų. Refinement led to a final conventional R ₁ value of 0.047 for 3406 reflections and 236 parameters. The caffeine complex 1 · C₈H₁₀N₄O₂ · CH₃OH · H₂O (3) crystallizes in the triclinic space group P1, a = 11.2892(4), b = 13.0367(8), c = 16.9700(11) Å, α = 82.902(2), β = 79.713(3), γ = 88.053(2)°, V = 2438(2) ų. Refinement led to a final conventional R ₁ value of 0.067 for 6393 reflections and 641 parameters. The resorcinarene displays the usual bowl shape in both compounds. The caffeine molecule in 3 is hydrogen bonded to two resorcinarene and one water molecules and one of its methyl groups is included in the cavity of a third macrocycle, suggesting CH₃…π interactions. Extended hydrogen bonding patterns involving phenolic protons and solvent molecules are also present in both compounds.