The 1,10 refer to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene.

Abbreviated "phen", it is used as a ligand in coordination chemistry, forming strong complexes with most metal ions.

Phenanthroline may be prepared by two successive Skraup reactions of glycerol with o-phenylenediamine, catalyzed by sulfuric acid, and an oxidizing agent, traditionally aqueous arsenic acid or nitrobenzene.

Alkyllithium reagents form deeply colored derivatives with phenanthroline.

The alkyllithium content of solutions can be determined by treatment of such reagents with small amounts of phenanthroline (ca.