Highly Light‐Sensitive Luminescent Cyanostilbene Flexible Dimers

Abstract

Switchable luminescent organic materials with unusual high light-sensitivity in the bulk at room temperature are described. The compounds consist of two promesogenic photoactive cyanostilbene units linked by a flexible spacer with an odd number of carbon atoms, analogous to the structural design of a liquid crystal dimer. Experimental and computational studies support the formation of excimers in solution due to the characteristic geometry of the dimers. In their condensed phases they show a high tendency to pack in lamellar phases, exhibiting bent-core lamellar liquid crystal phases and crystalline polymorphs with different photoluminescence and high quantum yields. The compounds are highly photoreactive, and their photoactivity in terms of photoisomerization and/or photocycloaddition reactions in solution and in the bulk is different. By irradiation of the compounds in the condensed phases at room temperature a fast photochemical process takes place, identified as a photocycloaddition reaction favored by the lamellar packing. Due to this photoreaction a luminescence modulation with green/blue color switching and an increase in quantum yield takes place.

Supramolecular Fluorescent Polymers Containing α-Cyanostilbene-Based Stereoisomers: Z/E-Isomerization Induced Multiple Reversible Switching

“…Then, after subsequent heating process, most of E -CNBP molecules convert to Z -CNBP, and the content of E -CNBP decreased to 5%. It should be noted that in some reported cases cyanostilbene can also take [2 + 2] cycloaddition in the bulk phase. − It could be identified as the appearance of a singlet at 5.39 ppm in 1 H NMR, which is due to the cyano-substituted cyclobutane ring. In the polymer complexes systems, only Z - and E -isomers are detected and no other reactions take place during UV irradiation and thermal treatment (Figure S10).…”

Dual Emission: Classes, Mechanisms, and Conditions

“…[56][57][58][59] Thep rocess can further take place between different molecular species,thereby leading to exciplex formation. Excimers and exciplexes can also be joined in an intramolecular fashion through linkers, [53,56,60] although the mechanism still involves the chromophors.I nm aterials science, excimer and exciplex formation has found particular interest in 3rd generation OLEDs. [61,62] * Fort he sake of completeness,t wo more correlated emitter processes should be mentioned that have found particular application in organic photovoltaics,a nd which may lead to possible DE3.…”

Photoinduced Dual-Mode Luminescent Patterns in Dicyanostilbene-Based Liquid Crystal Polymer Films for Anticounterfeiting Application

“…Therefore, linear-conjugated organic luminophores may be a good choice due to their similar structure with bulk materials. Owing to tunable luminescence emission and aggregate-induced enhanced emission (AIEE) properties, α-cyanodistyrylbenzene-based luminophores have attracted great interest in many applications, such as photonic devices, sensors, photoswitches, bioimaging, and stimuli-responsive photonic materials. , Furthermore, the cyanodistyrylbenzene unit can also undergo Z / E photoisomerization upon ultraviolet (UV) or visible light irradiation. − These features make the α-cyanodistyrylbenzene-based derivatives suitable for the construction of the polarized emission system. , …”