Anisotropy of dodecahedral water cages for guest gas occupancy in semiclathrate hydrates.

Anisotropic dodecahedral (D) water cages found in semiclathrate hydrates have unique gas selectivity due to their varied shapes. Herein, the D cages incorporating ideally isotropic rare gases, i.e., Xe, Kr and Ar, were characterized by crystal structure analyses. Stabilization mechanisms of the semiclathrate hydrates by the D cages are discussed.