Multicolor Photochromism of Fulgide Mixed Crystals with Enhanced Fatigue Resistance

Abstract

Two photochromic mixed fulgide single crystal systems showing multicolor photochromism and enhanced fatigue resistance were prepared with isostructural molecular pairs containing methyl-chloro and methyl-bromo groups. Parent crystals p-methylacetophenylisopropylidenesuccinic anhydride (1E), p-chloroacetophenylisopropylidenesuccinic anhydride (2E), and p-bromoacetophenylisopropylidenesuccinic anhydride (3E) showed light magenta, brownish orange, and orange colors, respectively, upon irradiation at 365 nm. Each two component mixed crystal MIX-1E and MIX-2E composed of 1E/2E and 1E/3E in a 0.39:0.61 and 0.88:0.12 ratio, showed four different colors upon irradiation with UV light and visible light of appropriate wavelengths. Further, it was found that colors of mixed crystals can be fine-tuned to impart different shades of colors over a range of four distinct colors shown by each, upon changing the length of the time irradiated at selected wavelengths. Such multicolored photochromic systems can be used to develop optoelectronic devices upon further improvements.

Molecular photoswitches in aqueous environments

“…29). In contrast to DAEs, fulgides and fulgimides contain only one (hetero)aromatic moiety, such as benzene, 409 (benzo)furan, [410][411][412] thiophene, 410,413,414 thiazole, 410 oxazole, 413 pyrazole, 410 pyrrole 413 and indole. 408,415,416 The second ringstructure is either a succinic anhydride (when YQO, Fig.…”

“…410 However, the C form benzene-based fulgides is thermally labile due to the higher degree of aromaticity of the benzene scaffold. 409 Irradiation of the C isomer with visible light leads to quantitative bleaching and electrocyclic ring-opening, and results in complete conversion to the E isomer. 412 The reaction in general proceeds in (benzo)furan-based fulgides less efficiently than in indolyl fulgides.…”

“…412,414 Photoisomerization can be repeated several times in various solvents, in polymer films and the solid state in both directions without formation of sideproducts, and is very robust. [409][410][411]414 Moreover, many fulgides and fulgimides show fluorescence, 408,420 which can vary between the two photoisomers. 416,421,422 Fulgides and fulgimides are used in a wide range of applications, for instance, as switchable polymer films, 413,420 on surfaces, 423 and in biological applications.…”

“… 410 However, the C form benzene-based fulgides is thermally labile due to the higher degree of aromaticity of the benzene scaffold. 409 …”

Fulgide Derivative-Based Solid-State Reversible Fluorescent Switches for Advanced Optical Memory

“…[1][2][3][4][5][6][7] In recent years, fluorescent switches based on diarylethene, spiropyran (SP), and fulgide (FUL), as well as their derivatives, have been reported. [8][9][10][11][12][13][14][15][16][17][18][19][20] However, most of the reported fluorescent switches were realized in solution. [21][22][23][24] Solid-state fluorescent switches are preferable in practical applications, such as anticounterfeiting, 25,26 data storage, 27,28 optical devices, 29 and biological imaging.…”