Which luminescence technique uses ruthenium tris chelate as a substrate?

• A. Chemiluminescence
• B. Bioluminescence
• C. Electrochemiluminescence
• D. Photoluminescence

Answer: (C)

Ruthenium tris(bipyridine) is a classic luminophore used in electrochemistry-driven light emission. In electrochemiluminescence, applying an electrical potential at an electrode initiates redox reactions that generate an excited state of the ruthenium complex, Ru(bpy)3^2+*, which then relaxes by emitting light. This combination of electrical stimulation and a ruthenium-based luminophore is why this technique is associated with ruthenium tris chelate. It differs from photoluminescence, where light is required to excite the emitter; and from chemiluminescence or bioluminescence, where light comes from chemical reactions without an electrode and typically do not rely on this specific ruthenium complex.