Transition metal complexes of 1,10-phenanthroline

In almost all complexes, phen serves as a bidentate ligand, binding metal centers with the two nitrogen atoms.

[11] Inhibition of the enzyme occurs by removal and chelation of the metal ion required for catalytic activity, leaving an inactive apoenzyme.

[7][13] Substituents at the 2,9 positions confer protection for the attached metal, inhibiting the binding of multiple equivalents of the phenanthroline.

[24] Complexes of phen and those of 2,2'-bipyridine (bipyr) are similar: the metal-ligand ensemble is planar, which facilitates electron delocalization.

As a consequence of this delocalization, phen complexes often exhibit distinctive optical and redox properties.