Complexes of benzo-15-crown-5 with protonated primary amines and diamines

Olga P. Kryatova, Ivan V. Korendovych, Elena V. Rybak-Akimova

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Three complexes of benzo-15-crown-5 (B15C5) with protonated primary amines [PhCH2NH3(B15C5)](ClO4), [p-C6H 4(CH2NH3)2(B15C5) 2](ClO4)2, and [(CH2) 4(NH3)2(B15C5)2](SCN)2 were isolated and studied in acetonitrile solutions by NMR, and in the solid state by X-ray crystallography. In all complexes, one B15C5 molecule was bound with each R-NH3+ moiety with characteristic small separation of 1.84-1.86Å between the nitrogen of the R-NH3 + group and the O5 mean plane of the crown residue. No sandwich-type complexes with a 1:2 R-NH3+/B15C5 stoichiometry were observed. Binding affinities of B15C5 in acetonitrile were similar for all ammonium cations studied: K1=550±10 M -1 for [PhCH2NH3]+; K 1=1100±100 and K2=400±30 M-1 for [p-C6H4(CH2NH3)2] 2+; and K1=1100±100 and K2=300±30 M-1 for [H3N(CH2)4NH 3]2+. The complexation is primarily enthalpy-driven (ΔH°=-4.9±0.5kcal/mol, ΔS°=-3.8±1.0eu for PhCH2NH3+-B15C5), as determined by variable temperature 1H NMR titrations.

Original languageEnglish (US)
Pages (from-to)4579-4588
Number of pages10
JournalTetrahedron
Volume60
Issue number21
DOIs
StatePublished - May 17 2004
Externally publishedYes

Keywords

  • Alkylammonium
  • Crown ethers
  • Host-guest complexes

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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