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Electroactive Polymers for Electrochromic Applications
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Adil A. Gobouri, Electroactive Polymeric Materials, 2022
Mahmoud H. Abu Elella, Emad S. Goda, Heba M. Abdallah, Shaimaa Elyamny, Heba Gamal, Esraa Samy Abu Serea, Ahmed Esmail Shalan
Viologens are conducting organic materials. In general, a sharp color is obtained by reducing the viologen dication, which led to intense absorption at the radical in its cation state. The color was mainly altered by the replacement groups presented on the nitrogen atoms of the bipyridinium salt. As shown in Figures 11.12(a and b), the absorption band for the radical cationic of ethyl viologen (V2) had a sharp peak detected at approximately 608 nm and a weak absorption band located in the near-UV irradiation region of 400–450 nm leading to a blue color after reduction (69). Other viologens with the substitution of alkyl chains behave optically the same as V2, such as like heptyl viologen (V3), methyl viologen (V1), vinyl benzyl viologen (V6), and benzyl viologen where the color of the radical cation at 600 nm might be a typical blue or violet-blue (70–72). However, when the aryl groups were used to substitute nitrogen contained bipyridinium as in cyanophenyl viologen (V5), phenyl viologen (V4) as shown in Figure 11.12, the viologens produced were colored green after reduction.
Electrochromics: Processing of Conjugated Polymers and Device Fabrication on Semi-Rigid, Flexible, and Stretchable Substrates
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Matthew Baczkowski, Sneh Sinha, Mengfang Li, Gregory Sotzing
Optical memory is the ability of the device to maintain its absorptive state over a period of time without applying an electric potential to the device. Viologens have low optimal memory due to diffusion through the device to the counter electrode, thus resulting in a change in the colored state, known as self-erasing electrochromism.16 In conjugated polymer devices, the EC layer is adhered to the electrodes allowing it to retain the absorptive state for longer periods of time, which can last from days to weeks.16 A device will not be able to maintain this state indefinitely due to the possibility of diffusion of the electrolyte and side reactions that may occur over time.
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
Recently, electron-transfer catalysis by viologen compounds has attracted much attention. The compounds function as mediators of electron transfer and have been applied in the reduction of aldehydes, ketones, quinines, azobenzene, acrylonitrile, nitroalkenes, etc., with zinc or sodium dithionite in a monophase or a two-liquid phase system [13]. Noguchi et al. [13] found that a redox-active macrocyclic ionene oligomer, cyclobis(paraquat- p-phenylene), acted as an electron phase-transfer catalyst for the reduction of quinines, as compared with acyclic benzyl viologen. The enhanced activity of this compound is due to the inclusion of the substrate into the catalyst cavity.
Synthesis, crystal structure and photochromic property of a phenethyl viologen bismuth(III) chloride
Published in Journal of Coordination Chemistry, 2019
Yu-Lin Wang, Xiao-He Chen, Wen Shu, Hao-Ge Qin, Jian-Di Lin, Rong-Guang Lin, Na Wen
However, it must be noted that these parameters are hardly tunable and predictable, because there are fewer examples of such compounds. In order to further examine the effect of the size of bismuthate-halide oligomers on photochromic properties, we continued to explore viologen-based photochromic inorganic-organic hybrids and a new analog with PeV2+ (N,N′-diphenethyl-4,4′-bipyridinium) as cation, (PeV)3(Bi2Cl9)2 (1), was obtained via self-assembly reaction by the simple combination of phenylethyl alcohol, BiCl3, 4,4′-bipyridine and concentrated HCl under solvothermal conditions, in which the PeV2+ dication was in situ generated. As is known, the class of compounds of viologens is very toxic and harmful to human health and the environment. Normally, the viologen cations were added as the starting reagents in the syntheses of viologen-based hybrids. The preparation of 1 with the in situ generation of PeV2+ dication, which avoids the formation the intermediates, can serve as a green and more efficient synthetic approach for the syntheses of viologen-based hybrid materials. In this article, we report the synthesis, crystal structure and the photochromic property of 1.