Photochromic Diarylethene Crystals

Thermally irreversible and fatigue-resistant photochromic diarylethene crystals have been developed in the past decade. The colored isomers are stable in the crystals, even at 100 °C and hardly return to the initial colorless isomers in the dark The thermally... 

Yamamoto, S., Matsuda, K., and Irie, M. (2003) Absolute asymmetric photocyclization of a photochromic diarylethene derivative in single crystals, Angew. Chem. Int. Ed., 42, 1636-1639. 

Irie, M., Kobatake S., and Horichi M. Reversible surface morphology changes of a photochromic diarylethene single crystal by photoirradiation- Science 2001, 291, 1769-1772. 

The photochromic behavior of the diarylethene crystals can be controlled by crystal engineering, namely the use of the it-it stacking phenomenon. Pentafluorophenyl substituted... 

Fukaminato, T., Kobatake, S., Kawai, T, and Irie, M. Three-dimensional erasable optical memory using a photochromic diarylethene single crystal as the recording medium. Froc. Jpn. Acad. 77, B, 30, 2001. 

The Dithienylethene System and Related Compounds. The area of diaryl-ethenes has been the subjeet of a review.Calculations have been carried out dealing with the photochromism of such compounds.A description of the preparation of diarylethene nanoparticles has been published, and a decrease in photocyclization was attributed to aggregation. Some novel photochromic diarylethenes have been synthesized. The photochemistry exhibited by these compounds suggests that they could be of use as optical switches.Tian and Yang have reviewed the area of diarylethene photochromic switches. 1,2-Bis(2-methylbenzo[b]thiophen-3-yl)hexafluorocyclopentene is at the basis of a new photochromic liquid crystal system. Yokoyama and his co-workers have patented details for such photochromic materials." ... 

The photoreactivity of DTE derivatives in the crystalline state is of special interest because of their potential usefulness for holographic and three-dimensional memories. In crystals, molecules are regularly oriented and packed in fixed conformations. In many cases, free rotation is inhibited. Therefore, the photoreactivity in the crystalline phase is dependent on the space for free rotation of the thienyl rings and the conformation formed in the crystal lattice. Several reports on the synthesis of metal complexes of photochromic diarylethenes and their photo-reactivity in the single-crystalline phase or the photoswitching of the coordination structure have been reported. These studies demonstrate that complexation to metal ions does not prohibit the photochromic reactions of the diarylethene units in the single-crystalline phase. 

M. Morimoto, S. Kobatake, M. Me, Crystal engineering of photochromic diarylethene single crystals, Chem. Rec., 4, 23-38 (2004). 

Irie et al. reported on the absolute reversible photocyclization reactions of achiral diarylethene 52 in chiral crystal leading to 53 in up to 99% ee. The asymmetric photochromic material has potential application in nonlinear optics, for example, in switchable second harmonic generation devices. [32]... 

Photochromism of diarylethene single crystals Crystal structures and photochromic performance. Chem. Commun., 3895-3905. 

Several photochromes of different structures (diarylethene and spirobenzopyran) were encapsulated in PS matrices to form composite nanoparticles with diameters between 70 and 150 nm [31], TEM images did not show phase-separated dye crystals in the nanoparticles. Hybrid films were prepared by spin-coating and investigated for their photochromic properties. After UV irradiation, the films changed their color according to the embedded photochrome. The reversibility of this process was shown by irradiation with light of 500-650 nm, which reinstalled the original state. 

M. Morimoto, M. Me, Photochromic reactions of diarylethenes in single crystals with intermolecular O-H- -N hydrogen bonding networks, Chem, Eur. J., 12, 4275-4282 (2006). 

As the geomeMcal structural changes are relatively small in the photochromic reactions, most of these reversible photoreactions could also proceed in the crystalline state. Thus, diarylethenes also exhibit crystalline state photochro-2.3 Benzopyran and naphthopyran (chromene) mism. Single crystals of the cocrystals with two or... 

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