1,10-Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. The 1,10 refers to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene.
Abbreviated "phen", or sometimes "o-phen" for ortho-phenanthroline, it is used as a ligand in coordination chemistry, forming strong complexes with most metal ions. It is often sold as the monohydrate.
Synthesis
Phenanthroline can 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. Dehydration of glycerol gives acrolein which condenses with the amine followed by a cyclization.
Reactions
Oxidation of 1,10-phenanthroline with a mixture of nitric and sulfuric acids gives 1,10-phenanthroline-5,6-dione.
1,10-Phenanthroline forms many coordination complexes. One example is the iron complex called ferroin.
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. 1 mg) followed by titration with alcohols to a colourless endpoint. Grignard reagents may be similarly titrated.
Pharmacology
Phenanthroline is used in biochemical and pharmacological research as an inhibitor of the deubiquitination enzyme Rpn11.
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