There continues to be a growing interest in using methyl viologen (MV2+) derivatives for a variety of electrochemical, photochemical, energy storage, and biomaterials-related applications. It is likely that viologen-based structures with unique multi-functional optoelectronic properties will become important areas for future energy storage materials development. We have synthesized a class of viologen materials that demonstrate both reversible electrochemical behavior and high fluorescence quantum efficiency that is deactivated with electrochemical reduction. The thiazolothiazole (TTz2+) viologens exhibit strong fluorescence with high quantum yields between 0.8 – 0.96. The TTz derivatives also show distinctive and reversible yellow to dark blue electrochromism at low reduction potentials. The fused bicyclic thiazolo[5,4-]thiazole heterocycle allows the pyridinium groups to remain planar, strongly affecting their electrochemical properties. The singlet quantum yield is greatly enhanced with quaternarization of the peripheral 4-pyridyl groups (ΦF increases from 0.22 to 0.96) while long-lived fluorescence lifetimes were observed between 1.8 - 2.4 ns. The TTz viologen materials have been characterized using various electrochemical techniques , UV-visible absorbance and fluorescence spectroscopy, spectroelectrochemistry, and time-resolved photoluminescence. The electrochemical properties observed in solution, in addition to their strong fluorescent emission properties, which can be suppressed upon 2 e- reduction, make these materials attractive for multi-functional optoelectronic, electron transfer sensing, electrochromic, and other photochemical / energy storage applications.

Fluorescent thiazolothiazole viologen materials for energy storage: Photochemistry, electrochromism, and photoluminescence

2019 Spring National Meeting

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