NiSO(4) and FeSO(4) self-assemble with heteroditopic ligands (L) comprising 2,2'-bipyridine and o-phenylene-(bis)urea cation- and anion-binding sites, respectively, into [ML(3)SO(4)] (M = Ni(2+), Fe(2+)) triple-stranded ion-pair helicates and mesocates.