Patent ID: 7918976

Claim:
A redox mediator having the formula: wherein M is iron, cobalt, ruthenium, osmium, or vanadium; L is a bidentate ligand comprising at least one imidazole ring; c is an integer selected from −1 to −5 or +1 to +5 indicating a positive or negative charge; X represents at least one counter ion; d is an integer from 1 to 5 representing the number of counter ions, X; and L 1 , L 2 , L 3 and L 4 are ligands, wherein L 1 and L 2 form a second bidentate ligand and wherein the second bidentate ligand comprises at least one substituted or unsubstituted heterocyclic nitrogen-containing-ring and wherein at least one of L, L 1 , L 2 , L 3 and L 4 is coupled to a polymeric backbone.