Synergistic luminescent spin-crossover materials bear great potential for the realization of spintronics components. As a result, substantial efforts have been invested in the search for molecule-based functional materials that undergo spin transitions while exhibiting detectable changes in their luminescent properties. This contribution explores the combination of pseudo-octahedral [Fe^IIN₆] chromophores with trivalent Ln(III) emitters in mixed d-f molecular entities. These system exploit the vast difference between the absorption spectra of the low-spin and high-spin configurations to tune the efficiency of the non-radiative Ln(III)→Fe(II) energy transfer processes with the aim of achieving the remote optical detection of the SCO process. The synthesis of an extended macropolycyclic heterometallic helicate with a unique d-f-f sequence is reported, and the thermodynamic self-assembly process in the presence of various lanthanide heteropairs is explored. A detailed kinetic analysis confirms the linear correlation between the total integrated intensity of the Eu(III)-centered emission and the increasing mole fractions of HS-Fe(II).