A new type of entanglement involving one-dimensional ribbons of rings catenated to a three-dimensional network in the nanoporous structure of [Co(bix)2(H2O)2](SO4)•7H2O[bix=1,4-bis(imidazol-1-ylmethyl)benzene]

Co-II sulfate reacts with the flexible ligand 1,4-bis(imidazol-1-ylmethyl)benzene (bix) to yield the coordination network [Co(bix)(2)(H2O)(2)](SO4).7H(2)O, containing polymeric ribbons of rings which penetrate and catenate a 3D single frame of the CdSO4 topology, to produce an open-channel entangled architecture with nanoporous behaviour.