NU-1000 consists of tetratopic 1,3,6,8-tetrakis(p-benzoate)pyrene linkers and Zr6(μ3-O)4(μ3-OH)4(H2O)4(OH)4 -nodes; see Figure . Each of the nodes is eight-connected, and ideally presents eight labile, or otherwise reactive, terminal aqua and hydroxo ligands, along with four potentially reactive, bridging hydroxos. Metal-cyanide complexes are known to bind at the surfaces of colloids and nanoparticulate films of TiO2 at low pH and to display metal-to-metal (cyanide complex to titanium) charge-transfer absorption bands in the visible region of the spectrum. Binding entails formation of Fe-CN-Ti linkages, likely by displacement of aqua ligands from the metal-oxide surface. Recognizing the close similarities in surface-attachment chemistry for zirconia versus titania and noting that the MOF's nodes are essentially tiny pieces of zirconia, we reasoned that similar binding of metal-cyanide complexes to NU-1000 would be possible; such direct installations of metal-cyanide ions in MOFs have not been reported previously.