Investigating the solid state hosting abilities of homo- and hetero-valent [Co7] metallocalix[6]arenes

Abstract

A family of homo-valent [Co(II)₇(OH)₆(L₁)₆](NO₃)₂ (1), [(MeOH)₂⊂Co(II)₇(OH)₆(L₁)₆](NO₃)₂ (2) (where L₁H = 2-iminomethyl-6-methoxyphenol) and hetero-valent [(NO₃)₂⊂Co(III)Co(II)₆(OH)₆(L₂)₆](NO₃)·3MeCN (4) (where L₂H = 2-iminophenyl-6-methoxyphenol) complexes possess metallic skeletons describing planar hexagonal discs. Their organic exteriors form double-bowl shaped topologies, and coupled with their 3-D connectivity, this results in the formation of molecular cavities in the solid state. These confined spaces are shown to behave as host units in the solid state for guests including solvent molecules and charge balancing counter anions. Magnetic susceptibility measurements on 2 and 4 reveal weak ferro- and ferrimagnetism, respectively. The utilisation of other Co(II) salt precursors gives rise to entirely different species including the mononuclear and trinuclear complexes [Co(II)(L₂)₂] (5) and [Co(III)₂Na(I)₁(L₃)₆](BF₄) (6) (where L₃H = 2-iminomethyl-4-bromo-6-methoxyphenol).