A porous layered metal-organic framework from π-π-stacking of layers based on a Co6 building unit

The coordination of benzene-1,3,5-tribenzoate (BTB) and imidazole (Im) with cobalt under basic conditions yields a 2D layered structure, Co-3(BTB)(1.5)(Im)(1.35)(O)(0.5)(OH)(0.5)(H2O)(1.65) guests (1), in which the imidazoles are weakly pi-pi stacked and hydrogen bonded to the adjacent layers affording a 3D supramolecular network. The structure is based on a hexanuclear Co-6 building unit which comprises four octahedral and two tetrahedral Co(II) centres. The framework is permanently porous to N-2, CO2 and CH4, with the strength of interaction at zero coverage being comparable to that at high loading. (C) 2012 Elsevier Inc. All rights reserved.