The contribution of the solvation energies to the assembly of polynuclear helicates reduces the free energy of intermetallic repulsion, DeltaE(MM), in condensed phase to such an extent that stable D(3)-symmetrical tetranuclear lanthanide-containing triple-stranded helicates [Ln(4)(L4)(3)](12+) are quantitatively produced at millimolar concentrations, despite the twelve positive charge borne by these complexes. A detailed modelling of the formation constants using statistical factors, adapted to self-assembly processes involving intra- and intermolecular connections, provides a set of five microscopic parameters, which can be successfully used for rationalizing the stepwise generation of linear bi-, tri- and tetranuclear analogues. Photophysical studies of [Eu(4)(L4)(3)](12+) confirm the existence of two different binding sites producing differentiated metal-centred emission at low temperature, which transforms into single site luminescence at room temperature because of intramolecular energy funelling processes.

Statistical mechanics predicts that the design of pure organized heteropolymetallic chains of metal ions bound to linear receptors depends on controlled deviations from the mixing rule DeltaE(MiMj) = 1/2 (DeltaE(MiMi) + DeltaE(MjMj)), whereby DeltaE(MiMj) is the intramolecular intermetallic interaction between neighboring metal i and metal j along the receptor. A thorough investigation of linear polymetallic trivalent lanthanide triple-stranded helicates shows that such deviations are amplified by an increase in the nuclearity of the final complexes and are thus easily evidenced in the tetranuclear heterobimetallic helicates [La(4-y)Lu(y)(L6)3](12+) (y = 0-4). The chemical and physical origins of this unprecedented behavior are discussed together with its practical consequences for programming pure heteropolymetallic 4f-4f complexes.

Complex twists: Following theoretical thermodynamic predictions, it is seen that the tetrametallic triple‐stranded lanthanide helicate [Ln4L3]12+ (see structure) dominates the speciation in solution at millimolar concentrations, despite its high positive charge. Isolation of the europium complex in the solid state unambiguously establishes its nanometric triple‐helical structure.

Liganden, die sich winden: In Einklang mit thermodynamischen Rechnungen liegt das Tripelhelicat [Ln4L3]12+ mit vier Lanthanoidionen (siehe Bild) – trotz seiner hohen positiven Ladung – bei millimolaren Konzentrationen in Lösung als Hauptspezies vor. Für den Europiumkomplex wurde diese nanometergroße tripelhelicale Struktur im Festkörper etabliert.