Reduction reactions at metal/non-aqueous interfaces can be sensed with the turn-on fluorophore resazurin

Abstract

Interfacial oxidation-reduction reactions have important applications in corrosion and catalysis, but traditional electrochemical cell methods cannot be used to study these reactions in non-conducting environments such as non-aqueous solvents. We...

A Turn-Off Fluorescent Sensor for Metal Ions Quantifies Corrosion in an Organic Solvent

“…It has been reported that water content in organic solvents (1-10%, v/v) affects the corrosion level detected by the reduction turn-on fluorescent sensor resazurin/resorufin. 29 As with any technique, the limitations of fluorescence corrosion sensors must also be considered. Besides PGSK, the responses of other commercial fluorescent sensors to metal ions in different environments we screened are reported in Fig.…”

“…44,50 For instance, we have reported that weakly fluorescent resazurin can sense corrosion by a reduction reaction to produce highly fluorescent resorufin in water and organic solvents, 29,51 and at single-molecule detection levels. 52 Though the investigation into resazurin reduction in nonconductive organic solvents remains under explored,Gatland, et al 29 have reported that reduction turn-on of resazurin can sense metal corrosion in organic solvents, even with a low H 2 O content of 1%. This finding suggests, to a certain extent, the potential efficacy of fluorophore reduction in detecting metal corrosion within organic solvents.…”

“…28 The utility of electrochemical approaches in non-aqueous environments is limited by the inadequate electrical conductibility of non-aqueous fluids. 29,30 With the need to move away from gasoline-powered vehicles, recent years have seen a rise in interest in ethanol-based biofuels. However, few studies have examined corrosion rates in situ in pure ethanol systems due to the low conductivity.…”

Getting the Most Out of Fluorogenic Probes: Challenges and Opportunities in Using Single-Molecule Fluorescence to Image Electro- and Photocatalysis

“…The p K a of resorufin in near 6, and the fluorescence intensity rapidly rises above this pH . Resazurin is typically used in aqueous solutions but can also be activated to resorufin in organic solvents including ethanol, acetone, and dimethyl sulfoxide (DMSO) . While the initial reduction of resazurin to resorufin is irreversible, resorufin can be reversibly reduced to dihydroresorufin, which is colorless and nonfluorescent.…”

“… 200 Resazurin is typically used in aqueous solutions but can also be activated to resorufin in organic solvents including ethanol, acetone, and dimethyl sulfoxide (DMSO). 201 While the initial reduction of resazurin to resorufin is irreversible, resorufin can be reversibly reduced to dihydroresorufin, which is colorless and nonfluorescent. Thus, additional control experiments are needed when using resazurin as a probe for reduction reactions to determine whether the turn-off events for individual fluorescent bursts are due to the desorption of resorufin from the surface of the catalyst or its further reduction to dihydroresorufin.…”