The one-electron oxidation of a Ru(II) phthalocyanine induces a dramatic colour change and provides a useful tool for the selective and highly sensitive colorimetric detection of copper(II) ions in neat aqueous solutions.
A colorimetric molecular probe for Cu(II) ions based on the redox properties of Ru(II) phthalocyanines
J. Mater. Chem. 2008, 18, 176-181.