Supertetrahedral sulfide crystals with giant cavities and channels

Although aluminosilicates and metal phosphates can form porous open-framework materials such as zeolites, sulfide analogs usually form high-density phases because of the relatively small tetrahedral angle at sulfur atoms. One strategy to overcome this limitation is to use tetrahedral clusters as the building blocks to achieve porous sulfide-based networks. The preparation and crystal structures of two indium sulfide open frameworks (ASU-31 and ASU-32) built of supertetrahedral clusters around organic template and water guests are described. ASU-31, based on the sodalite-tetrahedrite network, contains cavities 25.6 angstroms in diameter, and ASU-32, based on the tetragonal CrB4 network, contains channels with a minimum diameter of 14.7 angstroms. The organic cations can be completely exchanged with sodium ions in aqueous solution at room temperature without degradation of the crystals.