Redox-active ligands are compounds that can undergo reversible redox reactions, making them useful as metal complexes for energy storage and conversion applications. These ligands can form metal complexes with a variety of metals, including transition metals and lanthanides, and exhibit unique electronic and magnetic properties. Redox-active ligands are widely used in electrochemical cells, such as lithium-ion batteries and fuel cells, where they can store and release energy through reversible redox reactions. They also have potential applications in catalysis, where they can stabilize metal ions in active catalytic species and improve reaction efficiency and selectivity. In addition, redox-active ligands are used to synthesize coordination polymers and functional materials with unique properties, such as electrical conductivity and magnetic properties, for various technological applications.