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Botha F.,Institute of Chemical Technology Prague | Budka J.,Institute of Chemical Technology Prague | Eigner V.,ICTP | Hudecek O.,Institute of Chemical Technology Prague | And 3 more authors.
Tetrahedron | Year: 2014

A new type of calixarene-based receptor designed for the recognition of chiral anions was prepared by the introduction of (S)-2-methylbutan-1-ol moieties into the lower rim of calixarene. The immobilization of calixarene skeleton in the 1,3-alternate conformation enabled the construction of a cavity consisting of preorganised ureido functions and chiral substituents in close proximity. This cavity is capable of chiral discrimination of selected anions as demonstrated on d- and l-phenylalaninates. © 2013 Elsevier Ltd. All rights reserved. Source


Flidrova K.,Institute of Chemical Technology Prague | Slavik P.,Institute of Chemical Technology Prague | Eigner V.,ICTP | Dvorakova H.,Laboratory of NMR Spectroscopy | Lhotak P.,Institute of Chemical Technology Prague
Chemical Communications | Year: 2013

The regioselective mercuration of tetraalkylated calix[4]arenes with Hg(OCOCF3)2 leads to the formation of meta-substituted products which enabled Pd-catalysed intramolecular bridging within the calixarene skeleton. Bridged derivatives represent a completely novel substitution pattern in calixarene chemistry with extremely distorted cavities and possible applications in supramolecular chemistry. © 2013 The Royal Society of Chemistry. Source


Miksatko J.,Institute of Chemical Technology Prague | Eigner V.,UCTP | Dvorakova H.,Laboratory of NMR Spectroscopy | Lhotak P.,Institute of Chemical Technology Prague
Tetrahedron Letters | Year: 2016

An upper rim unsubstituted thiacalix[4]arene immobilised in the cone conformation was regioselectively oxidized to give all possible sulfoxide isomers using NaBO3·4H2O as the oxidizing reagent. Single crystal X-ray analysis undoubtedly assigned the stereochemistry of the sulfoxide group with the oxygen atom pointing toward the upper rim of the thiacalix[4]arene. As revealed by dynamic 1H NMR, the presence of the sulfoxide groups has dramatic consequences on the conformational behavior of the thiacalix[4]arenes. Namely, that the number of sulfoxide groups is inversely proportional to the ΔG barrier of the pinched cone–pinched cone equilibrium as determined by ΔG values 45.4 kJ/mol for monosulfoxide 5 and ΔG <32 kJ/mol for tetrasulfoxide 9. © 2016 Elsevier Ltd Source


Slavik P.,Institute of Chemical Technology Prague | Dvorakova H.,Laboratory of NMR Spectroscopy | Eigner V.,ICTP | Lhotak P.,Institute of Chemical Technology Prague
Chemical Communications | Year: 2014

The meta-iodo derivative, fixed in the cone conformation, enables the gram-scale preparation of a meta-bridged calix[4]arene. This intermediate, possessing a fluorene moiety within the macrocyclic skeleton, can be regioselectively alkylated on the corresponding methylene bridge to form a unique substitution pattern in classical calixarene chemistry. This journal is © the Partner Organisations 2014. Source


Hucko M.,Institute of Chemical Technology Prague | Dvorakova H.,Laboratory of NMR Spectroscopy | Eigner V.,ICTP | Lhotak P.,Institute of Chemical Technology Prague
Chemical Communications | Year: 2015

A simple and scalable synthesis of 2,14-dithiacalix[4]arene with alternating bridges (-CH2- and -S-) is reported. Proper selection of the bisphenol-based starting building blocks can provide not only the title compound (58%) but also yet unreported homooxa analogues possessing three different bridging units (-CH2-, -S- and -CH2-O-CH2-) in the molecule. These systems exhibit interesting conformational behaviour allowing for the study of flip-flop motion of the circular hydrogen bond arrays using dynamic NMR techniques. This journal is © The Royal Society of Chemistry 2015. Source

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