Rearrangement of hydrogen bonds in dehydrated raffinose tetrahydrate; A Time-of-flight neutron diffraction study

脱水和したラフィノース4水和物における水素結合の再配列

川崎 卓郎   ; 高橋 美和子*; 鬼柳 亮嗣  ; 大原 高志   

Kawasaki, Takuro; Takahashi, Miwako*; Kiyanagi, Ryoji; Ohara, Takashi

Structural changes of the raffinose crystal on dehydration from the pentahydrate to the tetrahydrate were investigated by single-crystal time-of-flight neutron diffraction. It was revealed that during the dehydration, rearrangement occurs in the hydrogen bonds related to the lost water molecule, while the symmetry of the crystal structure is retained. The hydrogen-bonding status of raffinose pentahydrate and tetrahydrate were discussed comprehensively according to Jeffrey's hydrogen-bonding classification. It was shown that water molecules are hydrogen bonded to the surrounding molecules by O-H...O hydrogen bonds and C-H...O hydrogen bonds, and the number of these two types of hydrogen bonds determines the water molecules that are removed by dehydration. The lattice constant c showed a significant decrease on dehydration and further dehydration leads to loss of crystallinity of the raffinose crystals.