What is "phenanthroline"

Phenanthroline \Phe*nan"thro*line\, n. [Phenanthrene + quinoline.] (Chem.) Either of two metameric nitrogenous hydrocarbon bases, C12H8N2, analogous to phenanthridine, but more highly nitrogenized.

n. (context organic compound English) A tricyclic heterocyclic compound having two pyridine rings fused with a benzene ring; any of its derivatives

Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. It is used as a ligand in coordination chemistry, it forms strong complexes with most metal ions.