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

Abstract

We report the first Co(ii) based discrete and extended network materials comprising the 2,2[prime or minute]-biphenol ligand. We first present the synthesis and magnetic characterisation of the Co(ii) dinuclear complexes [Co(ii)2(L)2(py)4][middle dot]2EtOH (1) and [Co(ii)2(L)2(4-pic)4].2LH2 (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][middle 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[prime or minute]-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[prime or minute]-tmdp = 4,4[prime or minute]-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.