Received 20 Oct 2015, Accepted 03 Dec 2015
First published online 07 Dec 2015
Hal Suzuki, Chiko Otani, Nobuto Yoshinari and Takumi Konno
Structural changes induced by water desorption from D-penicillaminato (D-pen) CuI8CuII6 clusters aggregated into three polymorphic crystal structures ((1) 1D helical, (2) 2D hexagonal sheet, and (3) discrete cubic) were investigated by terahertz (THz) absorption spectroscopy and X-ray diffractometry (XRD), which provided information on the skeletal and crystal structures of the clusters, respectively. The water molecules incorporated in the crystals were removed by evacuation and by heating to 100 °C. In the case of crystal 1, the helical structure collapsed upon water evacuation, whereas the skeletal structure of the D-pen CuI8CuII6 clusters did not change. However, the skeletal structures were distorted by the heating process. For crystals 2 and 3, water evacuation did not affect either the skeletal or the sheet and cubic crystal structures of the clusters, which, however, collapsed upon heating. The mechanisms driving these structural changes were discussed in relation to the type and amount of water molecules removed in each process.