Molecular Recognition Studies on Supramolecular Systems. 29. Anilino- and m-Toluidino-β-Cyclodextrins: Structural and Conformational Analyses and Molecular Recognition of Aliphatic Alcohols

Yu Liu, Chang Cheng You, Mieko Kunieda, Asao Nakamura, Takehiko Wada, Yoshihisa Inoue

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Mono(6-anilino-6-deoxy)-β-cydodextrin (1) and mono[6-(m-toluidino)-6-deoxy]-β-cyclodextrin (2) were synthesized and characterized. Circular dichroism and fluorescence spectral studies and fluorescence lifetime measurements have been performed to elucidate the conformations of 1 and 2 in aqueous buffer solution. 1-D and 2-D NMR spectra of 2 have been measured in D 2O to deduce its structure and detailed conformation in solution. From the circular dichroism, fluorescence, and NMR spectroscopic studies, it was revealed that the substituents appended to 1 and 2 penetrate into the cyclodextrin cavity forming a stable self-inclusion complex in aqueous solution, and also that the short linkage between the m-toluidino and cyclodextrin moieties makes the cyclodextrin ring of 2 deformed to some extent The complex stability constants (K S) of 1 and 2 for a series of aliphatic alcohols have been determined by using spectropolarimetric titrations in aqueous phosphate buffer solution (pH 7.20) at 25°C to elucidate the role of introduced substituents and the weak interactions involved in inclusion complexation by the modified cyclodextrins. The results obtained indicate that the van der Waals and hydrophobic interactions mainly contribute to the formation of complexes between the cyclodextrins and aliphatic alcohols, and the inclusion complexation process involves the induced-fit mechanism. Modified β-cyclodextrin 2 can recognize not only the size, shape, and hydrophobicity of the guest molecules, but also chiral guests, affording a moderate enantioselectivity of 1.55 for (+)/(-)-borneol.

Original languageEnglish
Pages (from-to)299-316
Number of pages18
JournalSupramolecular Chemistry
Volume12
Issue number3
Publication statusPublished - 2000
Externally publishedYes

    Fingerprint

Keywords

  • 2D-NMR analyses
  • Aliphatic alcohol
  • Inclusion complexation
  • Modified cydodextrins
  • Molecular recognition

ASJC Scopus subject areas

  • Chemistry(all)

Cite this