Time-Resolved Luminescence Spectroelectrochemistry at Screen-Printed Electrodes: Following the Redox-Dependent Fluorescence of [Ru(bpy)₃]²⁺

In this work, a compact instrument for time-resolved luminescence spectroelectrochemistry using low-cost disposable electrodes is reported. This instrument can be coupled with screen-printed electrodes via a specific cell and a reflection probe, which allows one to observe changes occurring at the electrode/solution interface. This approach allowed one to follow the fluorescence variation of electrofluorochromic species such as [Ru­(bpy)₃]²⁺ at screen-printed carbon electrodes. A strong correlation between the electrochemical processes and the fluorescence was found during potentiostatic or multipulsed amperometric measurements. A decrease of the fluorescence was observed when the [Ru­(bpy)₃]²⁺ was oxidized to [Ru­(bpy)₃]³⁺ and part of this fluorescence is recovered when [Ru­(bpy)₃]³⁺ was reduced to the initial species. Moreover, a significant increment of the fluorescence was found when the oxygen reduction reaction takes place, which also confirms its quenching effect. Finally, multipulsed amperometric detection was employed in order to obtain more information about the redox-dependent luminescence of [Ru­(bpy)₃]²⁺ finding a continuous quenching over time attributed to bleaching chlorine-based species