Circular and flip-flop hydrogen bonding in. beta. -cyclodextrin undecahydrate: neutron diffraction study

Crystal parameters have been determined by x-ray studies for ..beta..-cyclodextrin undecahydrate (..beta..-CD 11 H/sub 2/O) crystallized from water in a monoclinic space group P2. Two crystal forms were detected that differ slightly in unit cell constants and more significantly in the number of 11 and 12 water molecules associated with the ..beta..-cyclodextrin. Results of neutron-diffraction analysis to determine the hydrogen bonding scheme in the ..beta..-CD 11 H/sub 2/O are presented.