In addition to bipyridine and terpyridine ligands, there are many other types of ligands that can be used to form functional metal complexes. These ligands include a variety of organic and inorganic compounds, such as carboxylates, amines, and phosphates, which can coordinate with metal ions to form stable and functional complexes. The choice of ligand can significantly affect the properties and applications of the resulting metal complex, such as catalytic activity, optical properties, and stability. Researchers often explore new ligands and their coordination chemistry to discover new functional metal complexes with improved properties for specific applications. The diversity of ligands that can be used for functional metal complexes has led to a wide range of applications in various fields, including catalysis, sensing, and materials science.