Reticular coordination chemistry of oxalate-type ligands: Design principles for advanced multifunctional magnetic materials in emerging technologies

The design and synthesis of molecule-based multifunctional magnetic materials (MMMs) with desired chemical ( e.g. , host-guest, catalytic, acid-base, or redox) and physical ( e.g. , optical, magnetothermal, proton, or electron conducting) properties, in addition to magnetism, constitute a major goal in coordination chemistry. A deep knowledge of the metal-ligand self-assembly and metalloligand design approaches is essential for achieving the synergy that elevates classical molecular magnets and nanomagnets into the realm of MMMs. This review chronicles the journey of the versatile oxalato-type ligand family—including oxalate (ox), oxamate (oxa), oxamidate (oxm), dithiooxalate (dto), and tetrathiooxalate (tto)—in building homo- and heterometallic polynuclear complexes (PCs) and coordination polymers (CPs). These systems incorporate paramagnetic transition (nd, n = 3–5) and rare-earth (4f, 5f) metal ions, alongside diamagnetic alkaline or alkaline-earth ones, to construct MMMs ranging from discrete metal-organic clusters (MOCs) to extended metal-organic frameworks (MOFs). Ultimately, this review demonstrates how the foundational principles of magnetochemistry, established with this versatile ligand family, are now providing a robust blueprint for tackling the great challenges of the third millennium: designing advanced materials for quantum information processing, sustainable catalysis, selective molecular biosensing, diagnostic imaging, cryomagnetic refrigeration, water remediation, and chemical decontamination. • Presents a chronicle of the evolution of molecular magnetism through the unifying lens of the oxalato-type ligand family. • Traces the journey from magneto-structural principles to multifunctional magnetic materials design for emerging technologies. • Bifurcates the vast subject into homometallic (metal-ligand self-assembly) and heterometallic (metalloligand design) systems. • Illustrates the historical context and the current state-of-the-art from this specific ligand family. • Provides a robust blueprint for tackling the grand challenges of the “third frontier” of molecular magnetism.