Widely used as a catalyst in coupling reactions, especially in the formation of carbon–heteroatom bonds such as C–N, C–O, and C–S bonds. It is particularly effective in Ullmann-type reactions, enabling the synthesis of pharmaceuticals, agrochemicals, and functional materials under mild conditions. Its stability and solubility in organic solvents make it suitable for homogeneous catalysis. Also employed in the preparation of luminescent materials and coordination complexes due to its well-defined copper center and ligand environment.