0000000001084348

AUTHOR

Anca Pop

showing 2 related works from this author

Self-assembled dimers with supramolecular chirality

2003

The possibilities to form dimeric capsules with supramolecular chirality from tetraurea calix[4]arenes composed of two different phenolic urea units are discussed in general and demonstrated experimentally for various selected examples.

Supramolecular chiralityCrystallographyChemistryMaterials ChemistryMetals and AlloysCeramics and CompositesGeneral ChemistryCatalysisSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsSelf assembledChemical Communications
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Molecular Motions within Self-Assembled Dimeric Capsules with Tetraethylammonium Cations as Guest

2001

Hydrogen-bonded, dimeric capsules of calix[4]arenes substituted at the wide rim by four urea functions show unprecedented dynamic features when a tetraethylammonium cation is included as a guest. The seam of hydrogen bonds C=O...(HN)2C=O in the equatorial region which holds the two calixarene counterparts together changes its directionality fast (at 25 degrees C), while the dimer itself is kinetically stable on the NMR time scale. An energy barrier of deltaG++ = 49.9 kJmol(-1) (Tc 276 K) was estimated for this reorientation from variable-temperature (VT) NMR measurements. Lowering the temperature to about -50 degrees C restricts also the rotation of the encapsulated tetraethylammonium catio…

Magnetic Resonance SpectroscopyTetraethylammoniumMacromolecular SubstancesHydrogen bondDimerOrganic ChemistryTetraethylammoniumHydrogen BondingGeneral ChemistryNuclear magnetic resonance spectroscopyInteraction energyCatalysischemistry.chemical_compoundCrystallographychemistryCalixareneProton NMRThermodynamicsCalixarenesDimerizationTernary complexChemistry - A European Journal
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