Helical Folding of Alkanes in a Self-Assembled, Cylindrical Capsule

A. Scarso, Laurent Alain Claude Trembleau, J. Rebek Jnr

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

The reversible encapsulation of a series of normal alkane guests in a cylindrical host was studied by NMR methods. For small hydrocarbons such as n-pentane or n-hexane, two guests enter the host, and they move freely within. With n-heptane no encapsulation takes place. For longer alkanes such as n-decane, a single guest enters and the aromatic walls of the host are seen to twist to avoid empty spaces and increase favorable interactions with the hydrocarbon. The best guest (n-undecane) adopts a conformation with minimal gauche interactions. The longest alkane accommodated, n-tetradecane, adopts a helical conformation to fit in the cavity, a shape that maximizes CH/pi interactions with the aromatic walls of the receptor. These reciprocal conformational changes are discussed in terms of optimal host/guest interactions.

Original languageEnglish
Pages (from-to)13512-13518
Number of pages6
JournalJournal of the American Chemical Society
Volume126
DOIs
Publication statusPublished - 2004

Keywords

  • ENCAPSULATION COMPLEXES
  • MOLECULAR ENCAPSULATION
  • TEMPERATURE-DEPENDENCE
  • CHEMICAL-SHIFTS
  • RECOGNITION
  • ISOMERISM
  • PEPTIDES

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