Acta Crystallographica Section B

Structural Science

Volume 56, Part 2 (April 2000)

research papers

Acta Cryst. (2000). B56, 322-331 [ doi:10.1107/S0108768199014494 ]

Structure of the inclusion complex of -cyclodextrin with 1,12-dodecanedioic acid using synchrotron radiation data; a detailed dimeric -cyclodextrin structure

S. Makedonopoulou and I. M. Mavridis

Abstract: A detailed crystal structure study of the dimeric inclusion complex of [beta] -cyclodextrin ( [beta] CD) with 1,12-dodecanedioic acid is presented [IUPAC name: [beta] -cyclodextrin-1,12-dodecanedioic acid (2/1)]. The structure was solved with synchrotron high-resolution data (0.65 Å) at 100 K [crystal data: P1, Z = 1, a = 18.153 (7), b = 15.456 (8), c = 15.251 (4) Å, [alpha] = 102.81 (2), [beta] = 113.13 (2), [bold gamma] = 99.90 (3)°, V = 3673 (3) Å³, R = 0.0474 for 25 134 unique reflections with I > 2 [bold sigma] (I)]. Moreover, the room-temperature structure is used for comparison [crystal data: P1, Z = 1, a = 18.220 (3), b = 15.488 (3), c = 15.409 (3) Å, [alpha] = 102.903 (6), [beta] = 113.122 (5), [bold gamma] = 99.708 (5)°, V = 3735.2 (12) Å³, R = 0.0828 for 8235 unique reflections with I > 2 [bold sigma] (I)]. Combining the high-resolution data and the low-temperature made possible the location of the disordered guest molecule, 1,12-dodecanedioic acid, inside the wide cavity of the macrocycle formed by two [beta] CD monomers. Moreover, almost all the H atoms of the [beta] CD macrocycle and many of the water molecules have been located in the low-temperature structure. Thus, for the first time, it has been possible to show in detail, up to now only given by neutron diffraction data, that two [beta] CD monomers self-assemble through O3O3 intermolecular hydrogen bonds to form the [beta] CD dimer, as well as describe the hydrogen-bonding scheme between the dimer's hydroxyl groups among themselves and with water molecules in the lattice. The long guest threads through two host molecules forming a [3]pseudorotaxane. Its polar carboxyl groups, fully hydrated at the primary faces of the [beta] CD dimers, influence their packing so that those faces are exposed to the solvent. This is in contrast to the packing of the [beta] -cyclodextrin complexes of the corresponding aliphatic monoacids, where the dimeric complexes form channels in order to isolate the terminal methyl group from the water environment of the lattice.

Keywords: -Cyclodextrin dimer; 1,12-Dodecanedioic acid; Inclusion complex; [3]Pseudorotaxane; Synchrotron radiation.


	Structure factor file (CIF format) (1256.6 kbytes) Contains datablock final

	Structure factor file (CIF format) (479.0 kbytes) Contains datablock final

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