Tris(pentafluorophenyl)phosphine molecules in a new phase pack to form hourglass-shaped one-dimensional channels, whose inner surface is occupied by only fluorine. The channels show an effective diameter of 3.80 Å at the belly and only 2.68 Å at the neck, neither being possible for the encapsulation of any solvent molecules or for the permeability of air (N2 and O2), thus demonstrating an absolute vacuum. Such "vacuum"channels in the crystals have never been reported and would be of great significance in photo- and electrophysics. In addition...
