STRUCTURE OF THE 4-TERT-BUTYLBENZYL ALCOHOL BETA-CYCLODEXTRIN COMPLEX - COMMON FEATURES IN THE GEOMETRY OF BETA-CYCLODEXTRIN DIMERIC COMPLEXES

beta-Cyclodextrin-4-tert-butylbenzyl alcohol decahydrate, C42H70O35.C11H16O.10H2O, M(r) = 1479.40, orthorhombic, C222(1), a = 19.196 (7), b = 24.393 (6), c = 32.808 (9) angstrom, V = 15363 (8) angstrom 3, Z = 8, D(x) = 1.279 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.074 mm-1, F(000) = 6336, T = 295 (2) K, final R = 0.1127 for 4287 observed reflections with \F(o)\ greater-than-or-equal-to 3.0-sigma(\F(o)\). Two beta-cyclodextrin (beta-CD) molecules are held together by hydrogen bonds linking the secondary O(3)H hydroxyl groups to form dimers in the cavity of which two 4-tert-butylbenzyl alcohol molecules are accommodated. The interdimer space is filled with 10.2 water molecules distributed over 15 sites forming a dense hydrogen-bond network with themselves and the beta-CD hydroxyl groups. A comparison of beta-CD dimeric structures shows that the heptagonal symmetry of the beta-CD molecules is slightly affected by the nature and shape of the guest molecule. An important factor for the positioning and stability of the guest in the beta-CD cavity is the solvation of the guest polar group. The dimers form C-centered layers, the relative setting of which leads to four classes of molecular packing: channel, intermediate, screw channel and chessboard.