Electrofluorochromism: from molecular systems to set-up and display

Abstract

Electrofluorochromism deals with electrochemical monitoring of luminescence features. There are several reasons to be interested in that field. The first one is the design of displays working in a similar way to electrochromic devices, substituting colors due to absorption with colors due to emission, thus producing much higher brilliance. This requires designing smart molecules and materials, which are likely to exhibit reversible switch of emission by controlling their redox state. There are also a lot of analytical applications, especially in biochemical issues, where in situ dual detection of electrochemical and fluorescence signals can lead to very sensitive and selective biosensors. To achieve this goal, instrumental developments are necessary, involving, among others, beyond diffraction limit and single molecule detection optical techniques. This paper reviews the most recent developments in the above mentioned fields of fluorescence spectroelectrochemistry, coupled detection of fluorescence and electrochemical signals and design of molecules and materials exhibiting electrofluorochromic properties. The first part describes the required features for molecular systems to exhibit a reversible switch in their luminescence properties according to a change in their redox state. Examples among organic and organometallic dyes and redox labelled fluorophores are listed. The second part focuses on the instrumental development in fluorescence spectroelectrochemistry and recent coupling of electrochemical techniques with fluorescence microscopy. Finally, some applications and devices are presented in the last part of this review. This should give an overview of this emerging research field at the interface between physics, chemistry and biology.