Journal of Inclusion Phenomena and Macrocyclic Chemistry
36 (2): 191-215, February 2000
Copyright © 2000 Kluwer Academic Publishers
All rights reserved

Crystal Structures of the Inclusion Complexes of b-Cyclodextrin with Aliphatic Monoacids Tridecanoic Acid and (Z)-Tetradec-7-enoic Acid. Formation of [3]Pseudorotaxanes

Stella Makedonopoulou
Institute of Physical Chemistry, NCSR ``Demokritos'', 153 10 Aghia Paraskevi, Athens, Greece

John Papaioannou
Lab. of Phys. Chem., National and Kapodistrian University of Athens, Zografou, Athens, Greece

Ioulia Argyroglou
Institute of Physical Chemistry, NCSR ``Demokritos'', 153 10 Aghia Paraskevi, Athens, Greece

Irene M. Mavridis
Author for correspondence Institute of Physical Chemistry, NCSR ``Demokritos'', 153 10 Aghia Paraskevi, Athens, Greece

Abstract

The structures of the inclusion complexes of beta cyclodextrin with the aliphatic mono-acids tridecanoic acid (1) and (Z)-tetradec-7-enoic acid (2) have been determined at room temperature. Both compounds crystallise in P1, a = 15.654(6) Å, b = 15.650(6) Å, c = 15.937(6) Å, a = 101.58(1)°, b = 101.59(1)°, g = 103.58(1)°, Z = 1, for 1 and a = 15.6259(9) Å, b = 15.623(1) Å, c = 15.935(1) Å, a = 101.547(2)°, b = 101.555(2)°, g = 103.642(2)°, Z = 1, for 2. One molecule of the monoacids threads through two cyclodextrin macrocycles arranged in dimers thus forming [3]pseudorotaxanes. The host dimers are aligned along a channel in order to create a hydrophobic environment for the terminal methyl group of the guest and isolate it from the aqueous environment that surrounds the cyclodextrin dimeric units. The guests exhibit disorder over two orientations resulting in hydrogen bonding between the carboxyl groups of adjacent guest molecules along the channel and formation of carboxylic dimers. This crystal packing differs from that of b-CD complexes of homologous dicarboxylic acids.

Keywords
beta-cyclodextrin dimer, tridecanoic acid, (Z)-tetradec-7-enoic acid, [3]pseudorotaxane, supramolecular chemistry

Article ID: 206366