Stimuli‐Responsive Color/Fluorescence Dual‐Switching Behaviors of 1,10‐phenanthroline‐based Viologen Derivatives with Halogen Anions

Recently, stimuli-responsive color/fluorescence dual-switchable materials have attracted great attention, whereas most of them respond to monostimulus. Therefore, it is essential to design two or multi-stimuli-responsive color/fluorescence dual-switchable materials and develop their applications. Viologens, which respond to the electric potential, light irradiation, pH, and heat, are suitable for the construction of two- or multi-stimuli-responsive materials. Moreover, their easily modified chemical structure, tunable electronic properties, and excellent electrochemical characteristics can endow viologens with the desired color/fluorescence dual-switching behaviors. Herein, novel electro- and photo-stimuli responsive color/emission dual-switchable viologen derivatives phen-Vio[Cl- I-], phen-Vio[2Cl-] and phen-Vio[2I-] employing fluorophore 1,10-phenanthroline as an N-aryl substituent and halogen ions as anions are designed and synthesized. The introduction of 1,10-phenanthroline groups onto the viologen skeleton can endow viologen derivatives with the color/fluorescence dual-switching properties under electrical or light stimulus. While the introduction of halogen ions allows viologen derivatives to respond to both electrical and light stimuli simultaneously. Multifunctional devices fabricated with phen-Vio[Cl- I-], phen-Vio[2Cl-] or phen-Vio[2I-] as active materials exhibit excellent electrochromic/electrofluorochromic and photochromic/photofluorochromic performance. Additionally, anti-counterfeiting applications are successfully demonstrated by employing a commercial printer with self-made ink and papers. It is believed that this work has important guiding significance for the design and development of multifunctional materials and devices. Electro- and photo-stimuli responsive color/fluorescence dual-switchable viologen derivatives phen-Vio[Cl- I-], phen-Vio[2Cl-] and phen-Vio[2I-] are designed and synthesized employing fluorophore 1,10-phenanthroline as an N-aryl substituent and halogen ions as anions. Multifunctional devices and anti-counterfeiting applications are presented to demonstrate their excellent electrochromic/electrofluorochromic and photochromic/photofluorochromic performance, which provides strong guidance for the design and development of stimuli-responsive color/fluorescence dual-switching materials and devices. image