Molecular Pac-Man and Tacos: Layered Cu(ii) cages from ligands with high binding site concentrations

Abstract

The in situ formation and subsequent Cu(ii) ligation of the polydentate pro-ligands o-[(E)-(2-hydroxy-3-methoxyphenyl)methylideneamino]benzohydroxamic acid (L1H3), o-[(E)-(2-hydroxy-3-methoxy-5-bromophenyl)methylideneamino]benzohydroxamic acid (L2H3) and o-[(E)-(2-hydroxyphenyl)methylideneamino]benzohydroxamic acid (L3H3), leads to the self-assembly of the cages [Cu(ii)10(L1)4(2-aph)2(H2O)2](ClO4)4·5MeOH (1), [Cu(ii)14(L1)8(MeOH)2.5(H2O)7.5](NO3)4·3MeOH·7H2O (2), [Cu(ii)14(L2)8(MeOH)4(H2O)6](NO3)4·6H2O (3), [Cu(ii)14(L3)8(MeOH)6(H2O)2](NO3)4·4MeOH·8H2O (4) and [Cu(ii)30O(OH)4(OMe)2(L1)16(MeOH)4(H2O)2](ClO4)4·2MeOH·30H2O (5). Each member comprises a highly unusual topology derived from off-set, stacked, near planar layers of polynuclear subunits connected through long Cu(ii)-O contacts. The exact topology observed is dependent on the specific reaction conditions and methodologies employed. Dc magnetic susceptibility studies on 1, 2, 4 and 5 reveals strong antiferromagnetic exchange between the Cu(ii) centres in all siblings. We also present the 1D coordination polymer {[Cu(ii)(L4)]·H2O}n (6) comprising the pseudo macrocyclic ligand [[2-[(E)-(2-hydroxy-3-methoxy-phenyl)methyleneamino]benzoyl]amino]ethanimidate (L4H2), which is formed upon the incorporation of an MeCN unit at the hydroxamate group of precursor ligand L1H3.