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Merck

Helical folding of alkanes in a self-assembled, cylindrical capsule.

Journal of the American Chemical Society (2004-10-14)
Alessandro Scarso, Laurent Trembleau, Julius Rebek
RÉSUMÉ

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.

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Sigma-Aldrich
Mesitylene, 98%
Sigma-Aldrich
Mesitylene, reagent grade, 97%
Supelco
Mesitylene, analytical standard