A 3D Porous Metal Organic Framework Based on Infinite 1D Nickel(II) Chains with Rutile Topology Displaying Open Metal Sites

The reaction of Ni-II with a tetra-benzoate pyrene ligand produces a 3D porous framework based on infinite 1D Ni-II chains. The Ni-II-O connectivity and the formation of a hydroxo-bridge ((3)-OH) responsible for the connection of the central Ni-II atoms within the 1D Ni-II-((3)-OH)(2)-Ni-II chains can be straightforwardly compared with the Ti-IV-O-Ti-IV connectivity seen in TiO2. The arrangement of the TBAPy ligand around the 1D rutile-based chains leads in the generation of a porous framework with two distinct types of pores; based on the chemistries of these two types of pores, one can be labelled as hydrophobic and the other as hydrophilic. The use of different activation methods results in the generation of either a porous framework free of guest molecules or a completely solvent-free material, in which the terminal H2O molecules bound to Ni-II were removed, leading thus to a framework with open Ni-II sites. CO2 isotherms collected on both frameworks at 195 K and one barshowed type I isotherms characteristic of microporous materials (BET surface areas for: guest-free framework: 257(3) m(2.)g(-1); solvent-free framework: 362(2) m(2.)g(-1)). The affinity of both networks at zero coverage for both CO2 and CH4 was found to be greater when the unsaturated Ni-II sites are available within the void space.