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

Abstract

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)] 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)] was oxidized to [Ru(bpy)] and part of this fluorescence is recovered when [Ru(bpy)] 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)] finding a continuous quenching over time attributed to bleaching chlorine-based species.

Highly Reversible Electrofluorochromism from Electrochemically Decoupled but Electronically Coupled Molecular Dyads

“…Molecules exhibiting redox-active fluorescence changes are advantageous for their efficiency and tunability ( Figure 1b); however, not all fluorophores display electrofluorochromism. [20][21][22][23][24][25][26]28,32,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] The limited observance of electrofluorochromism originates from the irreversibility of the process; redox-responsive fluorophores usually undergo side reactions that involve destructive chemical step(s) following an electrochemical activation process. [29] To achieve fatigue-resistant electrofluorochromism, redoxstable fluorophores must be created.…”

Spectroelectrochemistry of Quantum Dots

“…Image of the instrumentation employed for luminescence spectroelectrochemistry at screen-printed electrodes. Reprinted with permission from Ref [50]. Copyright 2017 American Chemical Society.…”

Spectroelectrochemical Sensing: Current Trends and Challenges

“…Nevertheless, PL‐SEC measurements can be carried out without a perfect focus on the surface, obtaining reliable results that can be used to understand the electrode process . However, without a good optical alignment, is very difficult to obtain good limits of detection.…”

“…The development of a simple and reproducible PL‐SEC device is still a challenge that must be resolved. It should be noted that light emitting diodes (LED) sources have simplified extremely the experimental setups , using much cheaper instrumentation because both excitation wavelength selectors and lasers can be avoided.…”