The modulation of light emission by Fe(II) spin-crossover processes in multifunctional materials has recently attracted major interest for the indirect and non-invasive monitoring of magnetic information storage. In order to approach this goal at the molecular level, three segmental ligand strands L4-L6 were reacted with stoichiometric mixtures of divalent d-block cations (M(II) = Fe(II) or Zn(II)) and trivalent lanthanides (Ln(III) = La(III), Eu(III)) in acetonitrile to give C3-symmetrical dinuclear triplestranded helical [LnM(Lk)3] 5+ cations, which can be crystallized with non-coordinating counteranions. The divalent metal M(II) is six-coordinate in the pseudo-octahedral sites produced by the facial wrapping of the three didentate binding units, the ligand field of which induces variable Fe(II) spin-state properties in [LnFe(L4)3] 5+ (strictly high-spin), [LnFe(L5)3] 5+ (spin-crossover (SCO) around room temperature) and [LnFe(L6)3] 5+ (SCO at very low temperature). The introduction of the 2 * * D,A D,A