Study of conformational behavior of CMP(O)-cavitands by NMR spectroscopy and X-ray analysis in relation to the extraction properties

Harold Boerrigter, Willem Verboom, Ron Hulst, Gerrit J. van Hummel, Sybolt Harkema, David N. Reinhoudt

Research output: Chapter in Book/Report/Conference proceedingChapterAcademic

Abstract

Tetra-CMP(O)-functionalized cavitands are very effective europium(III) extractants. Cavitand 1b is the strongest ligand and has the highest extraction constant for 1:1 complexation with Eu(picrate)3 (viz. Kex 1 = 2.7 × 1012M−4). The conformational behavior of the CMP(O) cavitands 1a,b and 2a,b was studied by means of NMR spectroscopy. The introduction of an N-propyl substituent imposes large conformational differences due to inhibition of the free rotation around the amide N-C(O) bond. The Gibbs free energy of activation is about 75 kJ/mol for a rotation around the amide moiety (inwardoutward motion). The N-propyl-substituted cavitands form clusters; this aggregation originates from the association of propyl and pentyl chains of the cavitand molecules. The ability of bromomethylcavitand 3 to complex solvent molecules (e.g. CH2C12 or toluene) in the cavity is illustrated by a single crystal X-ray structure (with CH2C12).
Original languageEnglish
Title of host publicationNMR in Supramolecular Chemistry
EditorsM. Pons
Place of PublicationDordrecht
PublisherKluwer Academic Publishers
Pages19-35
ISBN (Electronic)978-94-011-4615-9
ISBN (Print)978-94-010-5950-3
DOIs
Publication statusPublished - 1999

Publication series

NameNATO ASI Series
PublisherKluwer Academic Publishers
Volume526
ISSN (Print)1389-2185

Keywords

  • Conformational behavior
  • Extraction property
  • ROESY spectrum
  • Amide moiety
  • Trivalent actinide

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