Diarylethene derivatives photochromism

Masahiro Irie received his B.S. and M.S. degrees from Kyoto University and his Ph.D. in radiation chemistry from Osaka University. He joined Hokkaido University as a research associate in 1968 and started his research on photochemistry. In 1973 he moved to Osaka University and developed various types of photoresponsive polymers. In 1988 he was appointed Professor at Kyushu University. In the middle of the 1980 s he invented a new class of photochromic molecules - diaryl-ethenes - which undergo thermally irreversible and fatigue resistant photochromic reactions. He is currently interested in developing singlecrystalline photochromism of the diarylethene derivatives. 

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. 

Such thermally irreversible photochromic chromophores represent the other class, classified as P-type (photochemically reversible type). Although many photochromic compounds have been so far reported, P-type chromophores are very rare. Only two families, furylfulgide derivatives and diarylethene derivatives, exhibit this reactivity.19 101 The photogenerated isomers of these derivatives are thermally stable and never revert to their initial isomers even at elevated temperatures (-100 °C). The thermally stable photochromic compounds offer potential for various applications in photoswitching and memory devices. 

The blue color was disappeared by irradiation with visible (X > 500 nm) light. In the dark, however, the blue color remained stable and at room temperature never reverted to the colorless form. In toluene, the colored isomer was found to be stable even at 100 °C. The stable, colored isomer was isolated by HPLC and its molecular structure was analyzed by NMR and X-ray crystallography. Both indicated that the blue colored isomer was the closed-ring form. Therefore, the photochromism of the diarylethene derivative was ascribed to the following photocydization and cycloreversion reactions. 

Some diarylethene derivatives that possess strongly electron-withdrawing substituents deviate from the general ruleJ5,23 The closed-ring isomers of 12b and 13b, possessing dicyanoethylene substituents, reverted to the open-ring isomers in 3.3 min and 186 min, respectively, at 60 °C. The dithienylethenes 14b, with pyridinium ion substituents, and 15b, with formyl residues, also underwent thermally reversible photochromic reactions. 

In this section, we propose a new switching unit, in which two radicals are placed in the same aryl unit and Jt-conjugated chain is extended from 2- and 5-positions of the thiophene ring in one aryl unit of the diarylethene [70]. The photochromic reactivity and magnetic switching of the new diarylethene derivatives will be discussed. 

M. Irie and M. Mohri, Thermally irreversible photochromic systems. Reversible photocyclization of diarylethene derivatives, J. Org. Chem. 53, 803-805 (1988). 

K. Uchida, S. Nakamura, and M. Irie, Photochromism of diarylethene derivatives. Stability of the closed-ring forms, Res. Chem. Intermed. 21, 861-876 (1995). 

Y. Nakayama, K. Hayashi, and M. Irie, Thermally irreversible photochromic systems. Reversible photocyclization of nonsymmetric diarylethene derivatives, Bull. Chem. Soc. Jpn. 64, 789-795 (1991). 

Hoshino, M., Ebisawa, F., Yoshida, T., and Sukegawa, K. Refractive index change in photochromic diarylethene derivatives and its application to optical switching devices. J. Photochem. Photobiol. A Chem. 1997, 105, 75. 

For any application of photochromic molecules, a discussion of the thermal stability of the colored form is in order. We will discuss two types of photochromic molecules (1) those that operate by a photon-heat mode (photochemical forward reaction and a thermal reverse reaction), such as spiropyran derivatives, and (2) those that exhibit a photon-photon mode, such as diarylethene derivatives. 

The second category of compounds—those operating by a photon-photon mode—comprises photochromic systems functioning photochemically in both the forward and backward reactions. Fulgide and diarylethene derivatives are representative examples (Scheme 1). 

Professor at Kyushu University. In the middle of the 1980 s he H invented a new class of photochromic molecules - diaryl-ethenes - which undergo thermally irreversible and fatigue resistant photochromic reactions. He is currently interested in developing singlecrystalline photochromism of the diarylethene derivatives. 

Figure 23.2 Diarylethene derivatives that show photochromism in the crystalline phase.

Figure 23.3 Photochromism of diarylethene derivatives in the single-crystalline phase.

Why is the thermal stability of diarylethene derivatives enhanced by replacing phenyl groups with furan or thiophene groups In molecular orbitals calculation, the photochromic reaction is treated as a typical electrocyclic reaction between hexatriene and cyclohexadiene. The thermal reaction proceeds disrotatorily and the photoreaction, conrotatorily. Disrotatory cyclization of A to B requires an increase in free energy larger than 138 kJ/mol, and hence no thermal ring-closure occurs in the case of either phenyl- or furan-substituted molecules (see... 

Several reviews have been published within the year which are of general relevance to the photoreactions of aromatic compounds. The subjects of these reviews include photochemistry in ionic liquids and in isotropic and anisotropic media, organic synthesis utilizing photoinduced electron-transfer reactions," heteroatom-directed photoarylation processes, photochromism, and photochemical molecular devices. Reviews more directly pertinent to the sections in the present chapter include those of the photoisomerization of five-membered heteroaromatic azoles, the photocycloaddition of benzene derivatives to alkenes, Diels-Alder additions of anthracenes, advances in the synthesis of polycyclic aromatic compounds, diarylethene-based photochromic switches, the photo-Fries rearrangement, and the application of Diels-Alder trapping of photogenerated o-xylenols to the synthesis of novel compounds. " A number of chapters in the two recently published handbooks of photochemistry and photobiology and in the revised edition of the text on photochromism are also pertinent to the current subject matter. 

T. Kawai, T. Kunitake, M. Me, Novel photochromic conducting polymer having diarylethene derivative in the main chain. Chem. Lett. 9, 905-906 (1999)... 

Sol 7. Photochromism is the reversible transformation of a chemical species between the two forms by the absorption of light, where the two forms have different absorption spectra. It can be described as a reversible change of color upon exposure to light. Such molecules find use as photoswitches in optoelectronic devices. For example, the given diarylethene derivative is capable of undergoing reversible chemical changes. They operate by means... 

T. Yamaguchi, M. Me, Photochromism of diarylethene derivatives having n-alkylbenzothiophene and n-alkylbenzofuran units. Bull. Chem. Soc. Jpn., 79, 1100-1105 (2006). 

T. Fukaminato, T. Sasaki, T. Kawai, N. Tamai, M. Me, Digital photoswitching of fluorescence based on the photochromism of diarylethene derivatives at a single-molecule level, J. Am. Chem. Soc, 126, 14843-14849... 

K. Uchida, M. Saito, A. Murakami, S. Nakamura, M. Me, Non-destructive readout of the photochromic reactions of diarylethene derivatives using infrared hght, Adv. Mater., 15, 121—125 (2003). 

Some selected examples of 1,2-diarylethenes were shown in this review. Miyasaka and Irie et al. revealed the three-photon cyclization and two-photon cycloreversion of diarylethens (223) by a near-infrared femtosecond laser pulse at 1.28 pm. They also found single-molecule fluorescence photoswitching of a diarylethene-perylenebisimide dyad (225)." " Photomechanical effects of two-component cocrystal (226) composed of 1,2-diarylethene derivative and perfluoronaphthalene or hydrogen-bonded diarylethene-imidazoline crystalline (227) were examined. A variety of photochromic reactions of 1,2-diarylethenes in crystalline states were reported by Iiie et al. ... 

Ishibashi Y, Fujiwara M, Umesato T, Saito H, Kobatake S, Irie M, Miyasaka H (2011) Cyclization reaction dynamics of a photochromic diarylethene derivative as revealed by femtosecond to microsecond time-resolved spectroscopy. J Phys (Them 115 4265-4272... 

Mori K, Ishibashi Y, Matsuda H, Ito S, Nagasawa Y, Nakagawa H, Uchida K, Yokojima S, Nakamura S, Irie M, Miyasaka H (2011) One-color reversible control of photochromic reactions in a diarylethene derivative three-photon cyclization and two-photon cycloreversion by a near-infrared femtosecond laser pulse at 1.28 pm. J Am Chem Soc 133 2621-2625... 

Irie M, Mohri M (1988) Thermally irreversible photochromic systems. Reversible photocycliza-tion of diarylethene derivatives. J Oig Chem 53 803-808. doi 10.1021/jo00239a022... 

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