Neocuproine, also known as 2,9-dimethyl-1,10-phenanthroline, is an organic compound that belongs to the family of phenanthrolines. It is a bidentate ligand widely recognized for its ability to form stable complexes with various metal ions, particularly copper(II). The compound appears as a pale yellow crystalline solid and is utilized in several analytical and synthetic applications due to its unique coordination properties and optical characteristics.