Old dog, new tricks: 2,2 '-biphenol as a bridging and book-end ligand in discrete and extended Co(II) architectures

We report the first Co(II) based discrete and extended network materials comprising the 2,2'-biphenol ligand. We first present the synthesis and magnetic characterisation of the Co(II) dinuclear complexes [Co(II)(2)(L)(2)(py)(4)]center dot 2EtOH (1) and [Co(II)(2)(L)(2)(4-pic)(4)].2LH(2) (2), both of which exhibit antiferromagnetic exchange between their Co(II) centres. The introduction of the co-ligand 2-hydroxypyridine (2-hpH) leads to the production of planar octametallic complex [Co (II)(8)(OMe)(2)(L)(4)(LH)(2)(2-hp)(4)(MeCN)(4)]center dot MeCN (3). Magnetic susceptibility and magnetisation measurements on 3 indicate dominant ferromagnetic exchange between the Co(II) centres. We also describe the first Co(II)/2,2'-biphenol extended networks in the shape of the 1D coordination polymer {[Co(II)(LH)(4,4-tmdp)(2)(NO3)](LH2)}(n) (4) (where 4,4'-tmdp = 4,4'-trimethylenedipyridine) and the 2D brickwall network [Co(II)(LH)(trans-bpe)(1.5)(NO3)] (5) (where trans-bpe = trans-1,2-bis(4-pyridyl)ethylene), comprising T-shaped nodes.