Novel extended viologen derivatives for photochromic and electrochromic dual-response smart windows

Photoinduced solid-to-liquid transition of an N-benzylideneaniline derivative towards smart glass

“…37,38 The reported smart windows based on azobenzene, viologen derivatives, silver halide, spiropyran and terephthalate derivatives are transparent in the initial state and become opaque after stimuli. 36 The smart glass in this study restored the translucent state spontaneously and quickly after removal of UV light, without the assistance of another wavelength light.…”

“…A kind of light-controlled smart glass with switchable transparency was further developed by constructing a doping system with MCN and one commercial nematic liquid crystal (LC), 4-cyano-4′-pentylbiphenyl (5CB). The initial state of the smart glass here was translucent, and became transparent after UV irradiation, which is different from the energy saving smart windows relying on photochromism, electrochromism, 36 thermochromism, and liquid crystals. 37,38 The reported smart windows based on azobenzene, viologen derivatives, silver halide, spiropyran and terephthalate derivatives are transparent in the initial state and become opaque after stimuli.…”

A Multistimuli-Responsive Cd-MOF Constructed by an Extended Viologen-Based Carboxylate Ligand

“…The inherent electron-deficient character of viologen groups enables them to undergo a color change by electron transfer to form stable viologen radicals in the presence of electron donor under external stimuli . Among various materials, metal–organic frameworks (MOFs) have received a lot of attention due to their well-defined structure and good crystallinity. − In recent years, a number of responsive MOF materials have been assembled by viologen derivatives and inorganic metal ions. ,, “Extended viologen” (ExV) is a kind of conjugated extended viologen, in which the stability of the reduced species can be enhanced by the introduction of π spacers between two pyridine units through a “π-conjugated extension” strategy. − However, studies of MOFs based on ExV are relatively limited. Therefore, we hypothesized that introducing the ExV unit into the MOF materials can make full use of the excellent chromic characteristic of viologen and the high stability of π-conjugated groups to improve the properties of the resultant materials. , …”

Tailorable and photochromic multifunctional methyl viologen/cellulose nanocrystal (CNC) films

“…1a). 14 Viologen derivatives are useful platforms for exploring photochromic applications like smart windows, 15 light-responsive erasable printing, 16 and optical memory media. 2,17 However, pristine MV showed poor responsiveness under ultraviolet (UV) light in solid or solution state because of self-quenching.…”