Valence tautomerism, non-innocence, and emergent magnetic phenomena in lanthanide-organic tessellations

Coordination networks based on lanthanide ions entangle collective magnetic phenomena, otherwise only observed in inorganic 4f materials, and the tunable spatial and electronic structure engineering intrinsic to coordination chemistry. In this review, we discuss the use of 2D-structure-directing linear {Ln^II/IIII₂} nodes to direct the formation of polymeric coordination networks. The equatorial coordination plasticity of {Ln^II/IIII₂} results in broad structural diversity, including previously unobtainable tessellations containing motifs observed in quasicrystalline tilings. The new phases host also magnetic frustration, which is at the origin of enhanced magnetic refrigeration potential. Finally, careful redox matching of Ln node and frontier orbitals of the ligand scaffold has culminated in the discovery of quantitative valence tautomeric conversion in a molecule-based Ln material, opening up new avenues for combining exotic magnetic phenomena with an encoded switch.