A dipyrenyl calixazacrown chemosensor for Mg

A new fluorogenic calix[4]tetraaza-crown-6 (4) bearing two pyrene amide groups has been prepared. It was shown to be selective for Mg²⁺. When Mg²⁺ is bound to 4, the pyrene monomer emission increased while the excimer emission declined in a ratiometric manner. It is shown by ¹H NMR that this ratiometric change is due to the conformational changes of the pyrenes during the chelation of Mg²⁺ by the amide functions to form a 1:1 complex.     

Bis(crown ether) and Azobenzocrown Derivatives of Calix[4]arene. A Review of Structural Information from Crystallographic and Modelling Studies

The association within one molecule ofcalix[4]arene and crown ether moieties leads toligands with new complexing properties. In particular,calix[4]arene bis(crown-6) and some of itsderivatives have been shown to be highly selectiveextractants for caesium ions. This review presents thebackground of the study and the results of crystalstructure determinations and molecular modellingcalculations performed during the investigation of twomolecular families, the bis(crown ether) and theazobenzocrown derivatives of calix[4]arene.     

A 1:1:1 chloro­form/tetra­hydro­furan solvate of p-tert-butyl­tetra­homo­dioxa­calix­[4]­arene

The title compound, 7,13,21,27-tetra-tert-butyl-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, crystallizes as a solvate with one mol­ecule of chloro­form and one mol­ecule of tetra­hydro­furan, C₄₆H₆₀O₆·CHCl₃·C₄H₈O. The calixarene assumes a cone-like conformation stabilized by intramolecular hydrogen bonds involving both phenolic and ether O atoms. The two solvent mol­ecules are located in each of the two half-cone cavities of the calixarene.     

Modular chemistry. Double- and multi-1,3-alternate-calixcrowns

Double- and multi-1,3-alternate-calixcrowns were prepared by multistep syntheses.     

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.     

A di-aza-benzo crown ether derived fromp-tert-butyl calix[4]arene. Synthesis and complexation of zinc cation

Di-aza-benzo crown etherp-tert-butyl calix[4]arene (1) has been prepared by hydrogenating the already known Schiff-base precursor (2). The metal ion complexing ability of (1) toward zinc cation is presented. The formation of a 2:1 (Zn: (1) complex and the location of zinc cations were deduced from¹H-NMR investigations.     

Separation of xylenes by extractive crystallization with calixarenes

Several calixarenes1–5 and benzopinacolone6 were recrystallized from 1:1:1 mixtures of the three xylene isomers.p-Iso-propylcalix[4]arene 1 was shown to extractp-xylene with 86% selectivity.p-Iso-propylbishomooxacalix[4]arene5 extractso-xylene with 84% selectivity.