p‐Methyl­tetrahomodioxacalix­[4]­arene

The title compound, 7,13,21,27‐tetramethyl‐3,17‐dioxapenta­cyclo­[23.3.1.1^5,9.1^11,15.1^9,23]ditriaconta‐1(29),5,7,­9(30),­11(31),‐12,­14,19(32),20,22,25,27‐dodecaene‐29,30,31,32‐tetraol, C₃₄H₃₆O₆, assumes in the solid state a very distorted cone‐like conformation stabilized by intramolecular simple and bifurcated hydrogen bonds involving both phenolic and ether O atoms. One part of the mol­ecule, comprising an ether link, is included in the cavity of an adjacent calixarene related by a screw axis, giving rise to a one‐dimensional self‐inclusion polymer.     

Properties of a Tetrahomodioxacalix[6]arene Derivative

The synthesis and X-ray crystalstructure of a novel tetrahomodioxacalix[6]arenehexamethylester 2 arepresented. Preliminary investigations of alkali metal ioncomplexation showed that 2 is apoor extractant with selectivity for lithium.     

Two triethylammonium ion complexes of monoanionic calix[4]arene

Two complexes between mono‐deprotonated calix­[4]­arene and Et₃HN⁺ are reported. The first, triethylammonium 26,27,28‐tri­hydroxy­penta­cyclo­[19.3.1.1^3,7.1^9,13.1^15,19]­octacosa‐1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23‐dodecaen‐25‐olate, C₆H₁₆N⁺·C₂₈H₂₃O₄^?, comprises only the cationic and anionic species, whereas the second, tris­(triethyl­ammonium) tris[26,27,28‐tri­hydroxy­penta­cyclo­[19.3.1.1^3,7.1^9,13.1^15,19]­octacosa‐1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23‐dodecaen‐25‐olate] aceto­nitrile solvate, 3C₆H₁₆N⁺·3C₂₈H₂₃O₄^?·C₂H₃N, comprises one aceto­nitrile solvent mol­ecule for three such units. In both cases, the units are stacked in columns so that the ammonium cation is hydrogen bonded to a phenolic or phenolate O atom of one mol­ecule and included in the hydro­phobic cavity of another neighbouring calixarene. The short contacts present indicate that cation?π and C—H?π interactions are likely to be involved in the inclusion phenomena.     

Synthesis,spectroscopic and magnetic characterization of some iron(III)-nucleotide compounds

Summary Magnetic moments and⁵⁷Fe M?ssbauer spectra at various temperatures of polycrystalline samples of some Fe^III-nucleotide compounds are described and have been characterized by u.v.-visible and fluorescence spectroscopy. Conclusions regarding the binding of iron(III) to nucleic acids are discussed.     

Recognition of amino acids by functionalized calixarenes

The calixarenic receptors exhibit remarkable host-guest properties towards biologically relevant guests. Aspects of complex formation reactions between both native and derivatized amino acids, di-and tripeptides with calixarenic (chiral or not) receptors are summarized in this critical review. Thus, the discussions emphasize the parameters that affect the molecular binding selectivity and efficiency of functionalized calix[n]arenes towards these substrates. A brief survey on their application in separation of amino acids is also considered (123 references).     

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.