title: Inclusion complexes of V-amylose with undecanoic acid and dodecanol at atomic resolution: X-ray structures with cycloamylose containing 26 D-glucoses (cyclohexaicosaose) as host.
abstract: Crystal structures are reported of cycloamylose containing 26 D-glucose residues (CA26, cyclohexaicosaose, C156H260O130) in complexes with undecanoic acid (CA26 x 2C10H21COOH x 34.95 H2O, orthorhombic P2(1)2(1)2(1), one CA26 and two bound undecanoic acids F1 and F2 in the asymmetric unit, resolution 0.95 angstroms) and with dodecanol ((CA26)(0.5) x C12H25OH x 32.0H2O, monoclinic C2, half a CA26 binding one dodecanol, A, in the asymmetric unit, resolution 1.0 angstroms). The macrocycle of CA26 is folded like the figure '8' into two 10 D-glucoses long left-handed V-amylose helices forming approximately 5A wide V-channels that are occupied by undecanoic acid (F1, F2) or dodecanol (A) as guest molecules. The functional head groups of the guests near the O(6) ends of the V-channels are hydrogen bonded with d-glucose O(6)n-H; the aliphatic termini beyond C(9) protrude from the O(2), O(3) ends. Parts of the aliphatic chains enclosed in the V-channels are all-trans except for one torsion angle each (approximately 130 degrees ) in undecanoic acid molecules F1 and F2. There are several (guest)C-H...O hydrogen bonds to O(4) and O(6) of CA26 in both complexes, and H...H van der Waals interactions with d-glucose C(3)-H and C(5)-H dominate. C(5)-H determine the position of the aliphatic chains of undecanoic acid F1 and of dodecanol A in contrast to F2 where both C(3)-H and C(5)-H contribute equally, probably because the V-channel is narrower than in F1 and in dodecanol. Complexes of polymeric V-amylose with fatty acids and alcohols studied by X-ray fiber diffraction could not provide the here described high resolution.
authors.affiliation: Institut für Chemie/Kristallographie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Nimz
authors.forename: Katrin
authors.initials: K
authors.lastname: Gessler
authors.forename: Isabel
authors.initials: I
authors.lastname: Usón
authors.forename: George M
authors.initials: GM
authors.lastname: Sheldrick
authors.forename: Wolfram
authors.initials: W
authors.lastname: Saenger
mesh_terms: D000688:Amylose / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003505:Cyclodextrins / Q000737:chemistry*; D007851:Dodecanol / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D003505:Cyclodextrins; D005227:Fatty Acids; C494562:cyclohexaicosaose; C016173:undecanoic acid; D007851:Dodecanol; D000688:Amylose; D005947:Glucose