Syntheses, Crystal Structures and Gas Sorption Properties of Prussian Blue Analogues Constructed from [Cr(CN)6]3- Building Blocks

Three isostructural porous Prussian blue analogues KM[Cr(CN)(6)]center dot H2O (M = Zn, Mn, Fe) with alkali metal cations K+ located within the pores of the frameworks have been constructed and characterized structurally. Thermal gravimetric analysis and variable-temperature powder XRD results indicate that the three porous materials are stable at high temperatures, and their frameworks are still retained after dehydration. The permanent porosities have been con-firmed by nitrogen and hydrogen sorption measurements at 77 K. Sorption studies show that the framework of FeCr with just 289 m(2)g(-1) BET surface area can take up a moderate amount of H-2 at 77K and 860 Torr [112 cm(3)(STP)g(-1), 0.71 wt.-1%], which indicates that the guest alkali metal cation K+ located in the pores can enhance the H-2 binding affinity within the dehydrated porous framework.