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.
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. Dehydration of glycerol gives acrolein which condenses with the amine followed by a cyclization.
In terms of its coordination properties, phen is similar to 2,2'-bipyridine (bipy) but binds metals more tightly since the chelating nitrogen donors are preorganized.
Many homoleptic complexes are known. Particularly well studied is [Fe(phen)3]2+, called "ferroin." It was used for the photometric determination of Fe(II). It is used as a redox indicator with standard potential +1.06 V. The reduced ferrous form has a deep red colour and the oxidised form is light-blue. The pink complex [Ni(phen)3]2+ has been resolved into its Δ and Λ isomers. Copper(I) forms [Cu(phen)2]+, which is luminescent.
The ferroin analogue [Ru(phen)3]2+ has long been known to be bioactive. 1,10-Phenanthroline is an inhibitor of metallopeptidases, with one of the first observed instances reported in carboxypeptidase A. Inhibition of the enzyme occurs by removal and chelation of the metal ion required for catalytic activity, leaving an inactive apoenzyme. 1,10-Phenanthroline targets mainly zinc metallopeptidases, with a much lower affinity for calcium.
A variety of substituted derivatives of phen have been examined as ligands. Neocuproine, 2,9-dimethyl-1,10-phenanthroline, is a bulky ligand, a very sensitive indicator of Cu ion. In "bathophenanthroline," the 4 and 7 positions are substituted by phenyl groups, a famous electron-transporting material for OLED. The more electron-rich phenanthroline ligand is 3,4,7,8-tetramethyl-1,10-phenanthroline.
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.
Shanghai UCHEM Inc. has been focusing on manufacturing of mono-substituted/ symmetric substituted-1,10-phenanthroline derivatives since 2011. Currently, there are around 50 1,10-phenanthroline derivatives available from their stockroom. Most of them could be supplied in kilograms, several popular derivatives are produced in hundreds kilograms. If you have needs for other kind of derivatives, please contact with UCHEM, who has service for customer synthesis.