X-ray structure of β-cyclodextrin-2,7-dihydroxy-naphthalene•4.6 H2O:: an unusually distorted macrocycle

The inclusion complex beta -cyclodextrin 2, 7-dihydroxynaphthalene(.)4.5 H2O crystallized in the monoclinic space group P2(1), with a = 14.082(3), b = 19.079(4), c = 12.417(3) Angstrom, beta = 109.28(3)9 V = 3149.0(11) Angstrom (3), and Z = 2. An X-ray study performed at room temperature shows that the crystal packing is of the herringbone type with one 2,7-dihydroxynaphthalene included completely in the beta -CD cavity, its long axis being oriented along the B-CD molecular axis, and 4.6 water molecules are placed in the interstitial space. The beta -CD macrocycle is elliptically distorted, and the guest molecule is held in the hydrophobic beta -CD cavity by C-H . . .O and C-H . . . pi interactions. (C) 2001 Elsevier Science Ltd. All rights reserved.