The Collaborative International Dictionary of English v.0.48:

Phenanthroline \Phe*nan"thro*line\, n. [Phenanthrene +
   quinoline.] (Chem.)
   Either of two metameric nitrogenous hydrocarbon bases,
   C12H8N2, analogous to phenanthridine, but more highly
   nitrogenized.
   [1913 Webster]