Complexes of organic ligands with a metal ion exhibit unique conformation
and spectroscopic properties upon changes in oxidation state of the metal ion.
The metal is a redox-active metal ion and may possess additional ligands bonded
to it. The organic ligand has three "arms" that are linked together at a central
atom; each arm contains atoms that may also coordinate to the metal ion. At least
two of the arms possess chromophoric properties. At least one arm contains two
different groups that may coordinate to the metal ion. In one oxidation state,
a first atom binds to the metal. In a second oxidation state, a second atom binds
to the metal. This change in coordination of the metal ion results in a rotation
of one of the arms, which changes the orientation of another group, which inverses
the orientation of the two chromophoric species with respect to one another.