Coordination-Directed Self-Assembly of Functional Polynuclear Lanthanide Supramolecular Architectures

Lanthanide supramolecular chemistry is a fast growing and intriguing research field due to the unique photophysical, magnetic, and coordination properties of lanthanide ions (Ln^III). Compared with the intensively investigated mononuclear Ln-complexes, polymetallic lanthanide supramolecular assemblies offer more structural superiority and functional advantages. In recent decades, significant progress has been made in polynuclear lanthanide supramolecules, varying from structural evolution to luminescent and magnetic functional materials. This review summarizes the design principles in ligand-induced coordination-driven self-assembly of polynuclear Ln-structures and intends to offer guidance for the construction of more elegant Ln-based architectures and optimization of their functional performances. Design principles concerning the water solubility and chirality of the lanthanide-organic assemblies that are vital in extending their applications are emphasized. The strategies for improving the luminescent properties and the applications in up-conversion, host-guest chemistry, luminescent sensing, and catalysis have been summarized. Magnetic materials based on supramolecular assembled lanthanide architectures are given in an individual section and are classified based on their structural features. Challenges remaining and perspective directions in this field are also briefly discussed.

A High-Symmetry Double-Shell Gd30Co12 Cluster Exhibiting a Large Magnetocaloric Effect

A high-nuclearity 3d-4f cluster of [Gd₃₀Co^II₆Co^III₆(OH)₅₆(NO₃)₁₂(CH₃COO)₃₀(H₂O)₃₀]·(NO₃)₂₂·(en)₃·(H₂O)₃ (1) was synthesized through the reaction of Gd(NO₃)₃·6H₂O, Co(NO₃)₂·6H₂O, and sodium acetate in a mixture of ethanediamine (en), ethanol, and deionized water. The cluster core in 1 features a double-shell structure with a Co₁₂ icosahedron encapsulating a Gd₃₀ icosidodecahedron. A magnetic study reveals that separating Co²⁺ ions with Gd³⁺ ions can effectively reduce the magnetic interaction of 3d-4f clusters. Significantly, the magnetocaloric effect (MCE) of 1 at 2 K and 7 T is up to 44.7 J kg^-1 K^-1, the largest MCE reported to date in the 3d-4f metal clusters.

Enhanced near-infrared luminescence in Ln2Cd2 (Ln = Nd, Yb) heterotetranuclear complexes

Due to the effect of the combination of the rigid structure and synergistic interactions of two ligands on energy transfer, the Cd–Ln complexes show excellent NIR luminescence properties with the QYs reaching 0.34% for Nd³⁺ and 2.13% for Yb³⁺.

Both magnetic relaxation and luminescence of Zn2Dy2 cluster complexes regulated by the bis-imine chain in Schiff base ligands

The bis-imine bridge in Schiff base ligands has effects on the magnetic relaxation and luminescence of two Zn₂Dy₂ cluster complexes.