ARTICLE pubs.acs.org/crystal
High-Convertible Photochromism of a Diarylethene Single Crystal Accompanying the Crystal Shape Deformation Seiya Kobatake,*,†,‡ Hiroki Hasegawa,† and Kentaro Miyamura† †
Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan ‡ Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi Center Building, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
bS Supporting Information ABSTRACT: We designed and fabricated thin single-microcrystals of a photochromic diarylethene, 1,2-bis(2-methoxy-5-phenyl-3-thienyl)perfluorocyclopentene, which exhibits photochromic reactions up to high conversion in high efficiency because the diarylethene molecule has extremely small photocycloreversion quantum yield. The thin microcrystals prepared on glass plates by sublimation underwent photochromism upon alternating irradiation with ultraviolet and visible light. The photocyclization reaction proceeded with more than 90% conversion in the crystalline phase, keeping the crystallinity. In addition to the high-convertible photochromic reaction in the crystalline phase, the crystals were found to exhibit the shape changes, such as contraction, bending, and separation, depending on the thickness of the crystal and the irradiation method with ultraviolet light. The intermolecular interaction between the photogenerated closed-ring isomers plays a significant role in deforming the crystal.
’ INTRODUCTION Molecular materials that reversibly change shape or size in response to external stimuli such as light have attracted much attention as photomechanical actuators because the materials can allow remote operation without any direct contact.15 Photoreversible transformation reactions of a chemical species between two isomers having different absorption spectra are referred to as photochromism.6 The two isomers differ from one another not only in the absorption spectra but also in various physical and chemical properties, such as refractive indices, dielectric constants, and oxidationreduction potentials. The instant property changes by photoirradiation without processing lead to their use in various optoelectronic devices, such as optical memory,7 photoswitching,8 display materials,9 and nonlinear optics.10 Furthermore, the photochromic compounds change geometrical structures during the photoisomerization. Among various types of photochromic compounds, diarylethenes have excellent characteristics, such as thermal stability of both isomers, fatigue-resistance, high sensitivity, high response, and high coloration quantum yield.11 Moreover, diarylethenes show photochromism not only in solution but also in the crystalline phase.12 The fatigue resistance of diarylethenes is improved in the crystalline phase. The side reactions with surrounding solvents, oxygen, or matrices are suppressed in the crystal.11 Recently, diarylethene molecular crystals with sizes ranging from 10 to 100 μm were found to exhibit rapid and reversible macroscopic changes in shape and size induced by ultraviolet (UV) and visible light.3 The molecular structure is changed by photoirradiation with UV light to result in shrinking r 2011 American Chemical Society
the size of the crystal lattice by several percentage. The photochromic conversion reached 70% conversion using the thin single crystal of the diarylethene. A rod-like crystal was bended by applying UV light, as looking like a heat bending phenomenon of bimetal. These phenomena were photoreversibly taken place upon alternating irradiation with UV and visible light. This is not an effect of heat but because of photoisomerization of the molecules. The bending state is thermally stable, and returns to the initial straight crystal by irradiation with visible light. The similar bending behavior has been found for other diarylethene and azobenzene crystals.1316 On the other hand, we have designed a single crystal of 1,2bis(2-methoxy-4-methyl-5-phenyl-3-thienyl)perfluorocyclopentene as the high-convertible photochromic crystal.17 However, the crystal exhibited the photocyclization reaction in only 50% conversion upon irradiation with UV light. It was found that the crystal has a unique molecular-packing structure in which photoreactive and photoinactive conformers are alternately stacked. The distances between the reactive carbon atoms for the two conformers are 0.365 and 0.493 nm, respectively. Only one of the conformers can efficiently cause the photocyclization reaction in the crystal.18 Consequently, the crystal formed alternating nanolayered structure of the open- and closed-ring isomer layers upon irradiation with UV light. These results indicate that the photoreactive conformers in the crystal can Received: November 1, 2010 Revised: February 18, 2011 Published: March 11, 2011 1223
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Scheme 1
isomerize in 100% conversion because the introduction of the methoxy groups at the reacting carbon atoms can suppress the photocycloreversion reaction. Here, we have applied to a photochromic diarylethene, 1,2bis(2-methoxy-5-phenyl-3-thienyl)perfluorocyclopentene (1a) (Scheme 1), which also shows photochromism with high photocyclization conversion in a solution. Diarylethene 1a has extremely small photocycloreversion quantum yield to result in reaching up to 100% conversion in a solution.19 If the diarylethene exhibits the photochromic reaction up to conversion as high as 100% in the crystalline phase, it has been attracted much attention not only in the research field of photochemistry and physical chemistry but also in the field of crystal chemistry as a fundamental research.
’ EXPERIMENTAL SECTION General. Solvents used were spectroscopic grade and purified by distillation before use. Infrared absorption spectra were taken by a JASCO FT/IR 430 connected with a JASCO IRT-30. Absorption spectra in the single-crystalline phase were measured by using a NIKON ECLIPSE E600 POL polarizing microscope connected with a Hamamatsu PMA-11 detector. The polarizer and analyzer were set in parallel to each other. Photoirradiation was carried out using a KEYENCE UV400 UV-LED lamp (365 nm). Materials. 1,2-Bis(2-methoxy-5-phenyl-3-thienyl)perfluorocyclopentene (1a) was prepared according to the literature.19 The closedring isomer (1b) was isolated by high performance liquid chromatography (HPLC) with a normal phase column (Kanto Mightysil Si60) using hexane/ethyl acetate (95:5) as the eluent after the hexane solution of 1a was irradiated with UV light. Single crystals 1a and 1b were obtained by recrystallization from hexane. Order Parameter. The good quality single crystals of 1a were used for the measurement of the order parameter. The single crystal was placed on a sample stage of the polarizing microscope under parallel nicols. The maximum (A0) and minimum absorbances (A90) were determined by measuring the absorption spectra at the different polarization directions. The order parameter (S) was estimated from the following equation: S ¼ ðA0 A90 Þ=ðA0 þ 2A90 Þ
X-ray Crystallography. The data collection was performed on a Bruker SMART1000 CCD-based diffractometer (50 kV, 40 mA) with Mo KR radiation. The data were collected as a series of ω-scan frames, each with a width of 0.3°/frame. The crystal-to-detector distance was 5.118 cm. Crystal decay was monitored by repeating the 50 initial frames at the end data collection and analyzing the duplicate reflections. Data reduction was performed using SAINT software, which corrects for Lorentz and polarization effects, and decay. The cell constants were calculated by global refinement. The structure was solved by direct methods using SHELXS-8620 and refined by full least-squares on F2
Figure 1. Photographs during crystal growth of diarylethene 1a by sublimation on a cover glass after heating for (a) 10, (b) 60, (c) 120, (d) 180, (e) 240, (f) 300, (g) 360, (h) 420, and (i) 480 min at 130 °C. using SHELXL-97.21 The positions of all hydrogen atoms were calculated geometrically and refined by the riding model. The data in CIF format have been deposited at the Cambridge Crystallographic Data Centre with deposition numbers CCDC 813608 (1a) and 813609 (1b).
’ RESULTS AND DISCUSSION Fabrication of Microcrystals. Single microcrystal 1a was prepared by sublimation on a thin glass plate by heating powder crystal 1a on an aluminum dish at 130 °C under atmospheric pressure. Figure 1 shows photographs of the crystal growth observed during the sublimation. At the initial stage of the sublimation, the isotropic liquid appeared on the glass plate. The small crystal nuclear already appeared after a few minutes. The crystal gradually became large, while the isotropic liquid was gradually increased because the diarylethene molecules came up from the dish. The crystal growth arose from the molecules in the isotropic liquid around the crystal. The resulting microcrystals were provided in the size of a few ten micrometers and the thickness of 10 nm to 1 μm. The size can be controlled by the heating temperature and time. Photochromic Conversion of Microcrystal 1a. Diarylethene 1a undergoes photochromism in solution. The photochromic behavior has already been reported.19 The colorless solution of 1a turns to blue upon irradiation with UV light. The blue colored solution of 1b returns to the initial 1a by prolonged irradiation with visible light. Because the photocycloreversion quantum yield is extremely small, it takes a long time of photoirradiation for the photocycloreversion reaction. The conversion from 1a to 1b in the photostationary state upon photoirradiation at 313 nm in hexane reaches 100%. Microcrystal 1a also turned to blue upon irradiation with UV light, and the blue-colored crystal returned to the initial openring isomer crystal by irradiation with visible light. The cycle process of the photocyclization and photocycloreversion reactions can be repeated several times. To evaluate the photochromic conversion, the photochromic reaction was followed by an infrared (IR) absorption spectroscopy using a microscope with IR light. Figure 2 shows IR spectral changes of thin singlemicrocrystal 1a upon photoirradiation at 365 nm. The open-ring isomer in the crystal has some characteristic bands at 1100, 1275, and 1400 cm1. These bands decreased after the UV light irradiation. The pure closed-ring isomer 1b which was isolated 1224
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Figure 3. Photocyclization conversion of 1a in the single-microcrystalline phase upon irradiation with 365-nm light.
Figure 2. Infrared absorption spectral changes of single microcrystal 1a upon irradiation with 365-nm light. The spectra were measured using an infrared microscopic spectrometer. The expanded spectrum is shown in b.
by HPLC has no absorption around 1400 cm1. The peak at 1400 cm1 can be regarded as a vibrational mode derived from the hexatriene framework.22 Since the hexatriene framework changes to the cyclohexadiene ring according to the photocyclization reaction, the absorption peak at 1400 cm1 disappears by irradiation with UV light. The conversion ratio from the open- to the closed-ring isomers can be determined from the decrease of the band at 1400 cm1. The photoconversion can also be checked by HPLC with a normal-phase silica gel column. The single microcrystal was irradiated with 365-nm light for 70 s, and was measured with IR spectroscopy to determine the photoconversion. It showed the presence of 88% of the closed-ring isomer. The colored microcrystal was dissolved in the mixture of ethyl acetate/hexane to analyze with HPLC. The separation of the two isomers by HPLC indicated that the ratio of the open and closed-ring isomers was 13:87. The consistency of IR spectroscopic analysis and HPLC indicates the accurate estimation of the photoconversion by IR spectroscopy. Figure 3 shows the photocyclization conversion of 1a in the single-microcrystalline phase upon irradiation with 365-nm light. The photocyclization reaction of thin crystal 1a proceeded as fast as that in a solution to result in high conversion in the photostationary state upon irradiation with UV light for a few minutes. The high photochromic conversion more than 95% in the diarylethene crystal is in the first report. In the most cases, the photochromic diarylethene crystal does not show high conversion as much as 100% because of the inner filter effect of the photogenerated closed-ring isomers and the photoreversibility in the photostationary state of the photocyclization/photocycloreversion reactions. Diarylethene 1a has high cyclization quantum yield and quite small photocycloreversion quantum yield in
Figure 4. Photographs of crystal 1a observed under polarized light before (a and b) and after (c and d) irradiation with 365-nm light.
solution. In addition to the fact, we could fabricate the thin microcrystal which can exclude the inner filter effect. To evaluate the crystallinity of the crystal in high conversion, the crystal was observed by a polarizing microscope under parallel nicols. Figure 4 shows photographs of the crystal observed under polarized light before and after irradiation with UV light. Before photoirradiation, the crystal was colorless. Upon irradiation with UV light the crystal turned to blue at a certain angle. When the sample stage was rotated as much as 90°, the blue color changed to pale blue. This is ascribed to the absorption anisotropy corresponding to the electronic transition moment of the closed-ring isomer because the molecules are regularly orientated in the crystal lattice.23 The color change was also evaluated by polarized absorption spectra. Figure 5 shows absorption spectra observed under polarized light. Two electronic transition moments exist in the visible region of the closedring isomer, short and long axes of the molecule. Therefore, when the crystal was rotated as much as 90°, the absorption maximum wavelength was shifted. The order parameter (S) was adopted to evaluate the crystallinity with high conversion, as expressed by the following equation: S ¼ ðA0 A90 Þ=ðA0 þ 2A90 Þ where A0 and A90 express absorbance at the maximum and minimum absorptions, respectively. At the initial stage of photoconversion, 15% conversion, the S value was estimated to be 0.44.24 The anisotropy was maintained even at the high conversion as high as 95%, S = 0.44. Figure 5d shows conversion dependence of the order parameter. From the initial stage to the high conversion, the order parameter was 1225
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Figure 5. Polarized absorption spectra of 1a in the single-microcrystalline phase upon irradiation with 365-nm light at the conversion of 15% (a), 43% (b), and 95% (c). The solid and dashed lines correspond to the maximum (A0) and minimum absorptions (A90), respectively, at the different polarization directions. Panel d shows change in order parameter (S) during photocyclization of single microcrystal 1a upon irradiation with 365-nm light. The S0 value expresses the S value at 15% conversion.
Table 1. X-ray Crystallographic Data for 1a and 1b 1a
Figure 6. Absorpation spectral change of crystal 1a upon irradiation with 365-nm light (a) and the maximum absorption wavelength according to the conversion (b).
constant, indicating that the crystallinity is maintained even at the high conversion without destruction of the crystal lattice. During the photocyclization reaction, the absorption maximum wavelength was shifted to longer wavelength. Figure 6 shows the absorption spectral change and the shift of the absorption maximum wavelength. At the low conversion less than 40%, the absorption maximum was not changed. However, at more than 40% conversion, it was shifted to longer wavelength.
1b
temp/°C
133(2)
133(2)
formula
C27H18F6O2S2
C27H18F6O2S2
formula weight
552.53
552.53
crystal system space group
monoclinic P21/c
monoclinic P21/c
a/Å
19.381(3)
16.235(2)
b/Å
11.541(2)
10.461(1)
c/Å
21.545(3)
15.224(2)
R/deg
90
90
β/deg
93.601(2)
112.103(2)
γ/deg
90
90
volume/ Å3 Z
4809.4(11) 8
2395.5(4) 4
Fcalcd, g/cm3
1.526
1.532
reflns measured
6542
8043
R1 (I > 2σ(I))
0.0335
0.0325
R2 (all data)
0.0887
0.0886
GOF
1.007
1.028
The difference between the maximum wavelengths at the low and high conversions was ∼40 nm. The shift of the absorption maximum is considered to be ascribed to (i) the change in the surrounding around the molecule, (ii) the stress of the molecule, and (iii) the change in the π-conjugation length. To consider for the influence of the surrounding around the molecule, we checked the difference in absorption maximum wavelength in the amorphous film of 1a upon irradiation with UV light. The absorption maximum wavelength of 1b was observed at 640 nm in the bulk amorphous state of 1a. It did not change 1226
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Figure 7. ORTEP drawings of 1a (a, b) and 1b (c) showing 50% probability displacement. There are two crystallographically independent molecules A (a) and B (b) in the asymmetric unit in the crystal 1a.
even at any photochromic conversion. This indicates that the spectral shift is not due to the influence of the surrounding around the molecule. The absorption spectral shift to the longer wavelength in the crystal compared with that in solution was observed in 1,2bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene.25 The photogenerated closed-ring isomer in the crystal is attributable to the strained molecular structure of the closed-ring isomer in the crystal lattice of the open-ring form. The spectral shift of 1a is different from this case. At the low conversion, the absorption maximum wavelength of 1b in the crystal is almost the same as that in hexane. However, the wavelength was gradually shifted to the longer wavelength according to the photochromic reaction. The closed-ring form molecules at the low conversion are surrounded by the open-ring form molecules. Therefore, the absorption spectral shift should arise from the stress even at the low conversion. This means that the spectral shift is not due to the stress of the molecule. We propose that this spectral shift is due to the change in the π-conjugation length of the closed-ring isomer 1b. To clarify the fact, the crystal structure was examined in the following section. X-ray Crystallography. To clarify the molecular structure and the molecular packing of the open- and closed-ring isomers in the crystals, X-ray crystallographic analysis of crystals 1a and 1b were carried out. The crystallographic data are listed in Table 1. Figure 7 show ORTEP drawings of 1a and 1b. The crystal of 1a belongs to a monoclinic system, P21/c and Z = 8. The crystal has two molecules in the asymmetric unit. These molecules are referred to as molecules A and B here. The molecular packing of 1a viewed along the b axis is shown in Figure 8a. Molecules A and B are expressed by red and blue lines, respectively. The same types of the molecules are arranged in a line along the c axis, and the layers of molecules A and B are stacked alternatively. Both molecules are packed in an antiparallel conformation. The distance between the reacting carbons are 0.332 and 0.327 nm for molecules A and B, respectively. This indicates that both conformers have a potential for photocyclizaion by photoirradiation.18 On the other hand, the crystal of the diarylethene closed-ring isomer 1b belongs to a monoclinic system, P21/c and Z = 4. The crystal has only a molecule in the asymmetric unit. When the molecular packing of the closed-ring isomer was viewed along the b axis, the similar molecular packing as that of the open-ring isomer was observed as shown in Figure 8b though the cell volume of 1b is a half of that of 1a.
Figure 8. Molecular packing of 1a (a) and 1b (b) viewed along the b axis. Crystallographically independent molecules A and B for 1a were drawn by red and blue lines, respectively. The crystal of 1b has only a molecule (red) in the asymmetric unit. The short contact interaction in 1b (b) corresponds to the intermolecular interaction.
The crystal of 1a consists of a dimer structure by the intermolecular interaction between the phenylthiophene groups. On the other hand, in the case of 1b, there is a polymeric structure along the b axis by the intermolecular ππ interaction between the phenylthiophene groups. The phenyl group in one side of 1a molecule is distorted with the molecular plane, and the π-conjugation of the phenyl ring with the thiophene ring is not enough. On the other hand, both phenyl groups in 1b are almost parallel to the molecular plane. It is considered that the reaction proceeded to 1b molecule without accompanying the rotation of the phenyl group at the low conversion when reacting from 1a to 1b in the crystal. At the middle conversion, the phenyl group in 1b could be rotated to stabilize 1b molecule in the crystal because of the presence of some 1b molecules around 1b. That is, the phenyl group does not become parallel to the molecular plane at the low conversion, and the π-conjugation on the close-ring form 1blow is short, as shown in Figure 9. Next, according to higher photoconversion, the molecule of 1b is adjacent to other 1b molecule, and 1blow becomes the closed-ring form 1bhigh. The conformational change in the closed-ring form 1b may be assisted by the intermolecular ππ interaction. The closed-ring form 1bhigh is conjugated with the entire molecule by the planarity between the phenyl groups and the central part. This fact indicates that the absorption maximum wavelength was shifted to longer wavelength.26 Crystal Deformation. In some microcrystals of 1a, the crystals show deformation such as contraction, bending, and separation. Typical examples of the deformations are shown in Figure 10. In the case of the contraction in Figure 10a, the length of the long 1227
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Figure 9. Molecular structure changes during the photochromic reaction in the crystal. The phenyl rings in the left side of 1a and 1blow are tilted.
’ CONCLUSION We designed and fabricated thin single-microcrystals of 1,2bis(2-methoxy-5-phenyl-3-thienyl)perfluorocyclopentene, which exhibits photochromic reactions up to high conversion in high efficiency. The photochromic reaction reached more than 90% conversion in the crystalline phase, keeping the crystallinity. In addition to the high-convertible photochromic reaction in the crystalline phase, the crystals were found to show the shape changes such as contraction, bending, and separation, depending on the thickness of the crystal and the irradiation method with ultraviolet light. The intermolecular interaction of the photogenerated closed-ring isomers plays a significant role in deforming the crystal. ’ ASSOCIATED CONTENT
bS Figure 10. Crystal deformation of contraction (a f b), bending (c f d), and separation (e f f) of crystal 1a upon irradiation with 365-nm light.
Supporting Information. CIF files of compounds 1a and 1b. This material is available free of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION Corresponding Author
axis in the crystal decreased as much as ∼6% upon UV irradiation. However, the length of the short axis did not change. The contraction is because of the homogeneous photoirradiation to the entire crystal. On the other hand, the heterogeneous photoirradiation led to the bending of the crystal as shown in Figure 10b. Only the surface of the crystal was contracted by photoirradiation. These deformations were caused by the intermolecular interaction of the photogenerated closed-ring isomers. When the deformed crystals were irradiated with visible light, the blue color returned to the initial colorless, but the crystal shape did not completely return to the initial shape. The irreversibility of the crystal deformation may be ascribed to the conformational change of the phenyl ring as shown in Figure 9. When the molecules are irradiated with UV light, the 1a molecule changed to 1blow, and then the conformation of 1blow changes to 1bhigh at more than 40% conversion. After the irradiation with visible light, the different conformational molecule 1a for the phenyl ring may be caused by the photocycloreversion reaction. In most cases in high conversion, the crystal makes a gap at the central part to separate the crystal in a direction perpendicular to the long axis of the crystal. This is also because of the contraction of the crystal by the intermolecular interaction of the photogenerated closed-ring isomers. We examined the location of the gap for more than 100 samples. The gap was formed at the central part of the long axis in the crystal with 10% of the standard deviation. This indicates that the strain of the crystal by the intermolecular interaction of the photogenerated closed-ring isomers was homogeneously caused in the entire crystal, and the gap was formed at the central part in the crystal.
*E-mail:
[email protected].
’ ACKNOWLEDGMENT This work was partly supported by a Grant-in-Aid for Scientific Research on Priority Area “Strong Photon-Molecule Coupling Fields” (470) (No. 21020032) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and PRESTO, Japan Science and Technology Agency. ’ REFERENCES (1) (a) Merian, E. Text. Res. J. 1966, 36, 612–618. (b) Eisenbach, C. D. Polymer 1980, 21, 1175–1179. (c) Agolini, F.; Gay, F. P. Macromolecules 1970, 3, 349–351. (d) Matejka, L.; Ilavsky, M.; Dusek, K.; Wichterle, O. Polymer 1981, 22, 1511–1515. (e) Irie, M. Adv. Polym. Sci. 1990, 94, 28–67. (f) Finkelmann, H.; Nishikawa, E.; Pereira, G. G.; Warner, M. Phys. Rev. Lett. 2001, 87, 015501. (2) (a) Yu, Y.; Nakano, M.; Ikeda, T. Nature 2003, 425, 145. (b) Ikeda, T.; Nakano, M.; Yu, Y.; Tsutsumi, O; Kanazawa, A. Adv. Mater. 2003, 15, 201–205. (c) Yu, Y.; Nakano, M.; Shishido, A.; Shiono, T.; Ikeda, T. Chem. Mater. 2004, 16, 1637–1643. (3) (a) Kobatake, S.; Takami, S.; Muto, H.; Ishikawa, T.; Irie, M. Nature 2007, 446, 778–781. (b) Irie, M. Bull. Chem. Soc. Jpn. 2008, 81, 917–926.(c) Kobatake, S.; Irie, M. In Molecular Nano Dynamics Vol. 2 Fukumura, H., Irie, M., Iwasawa, Y., Masuhara, H., Uosaki, K., Eds.; Wiley-VCH: Weinheim, Germany, 2009, pp 443457. (4) (a) Al-Kaysi, R. O.; M€uller, A. M.; Bardeen, C. J. J. Am. Chem. Soc. 2006, 128, 15938–15939. (b) Al-Kaysi, R. O.; Bardeen, C. J. Adv. Mater. 2007, 19, 1276–1280. (c) Al-Kaysi, R. O.; Bardeen, C. J. Chem. Commun. 2006, 1224–1226. 1228
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Crystal Growth & Design (5) Balzani, V.; Credi, A.; Venturi, M. Molecular Devices and Machines—A Journey into the Nanoworld; Wiley-VCH: Weinheim, Germany, 2003. (6) (a) Brown, G. H. Photochromism; Wiley-Interscience: New York, 1971. (b) D€urr, H.; Bouas-Laurent, H. Photochromism: Molecules and Systems; Elsevier: Amsterdam, 1990. (7) (a) Irie, M. Photo-reactive Materials for Ultrahigh Density Optical Memory; Elsevier: Amsterdam, 1994. (b) Irie, M. Photochromism: Memories and Switches. Chem. Rev. 2000, 100 (5), entire issue.(c) Irie, M.; Matsuda, K. Memories. In Electron Transfer in Chemistry; Balzani, V., Ed.; Wiley-VCH: Weinheim, Germany, 2001; Vol. 5, pp 215242. (d) Irie, M. High-Density Optical Memory and Ultrafine Photofabrication. In Nano-Optics; Kawata, S., Ohtsu, M., Irie, M., Eds.; Springer: Berlin, Germany, 2002; pp 137150. (8) (a) Irie, M. Photoswitchable Molecular Systems Based on Diarylethenes. In Molecular Switchings; Feringa, B. L., Ed.; WileyVCH: Weinheim, Germany, 2001; pp 3762. (b) Matsuda, K.; Irie, M. Photoswiching of Intermolecular Magnetic Interaction Using Photochromic Compounds. In Chemistry of Nano-molecular Systems—Toward the Realization of Molecular Devices; Nakamura, T., Matsumoto, T., Tada, H., Sugiura, K.-I., Eds.; Springer: Berlin, Germany, 2002; pp 2540. (9) (a) Yao, J.; Hashimoto, K.; Fujishima, A. Nature 1992, 355, 624–626. (b) Bechinger, C.; Ferrer, S.; Zaban, A.; Sprague, J.; Gregg, B. A. Nature 1996, 383, 608–610. (10) (a) Nakatani, K.; Delaire, J. A. Chem. Mater. 1997, 9, 2682–2684. (b) Delaire, J. A.; Nakatani, K. Chem. Rev. 2000, 100, 1817–1845. (11) Irie, M. Chem. Rev. 2000, 100, 1685–1716. (12) (a) Kobatake, S.; Irie, M. Bull. Chem. Soc. Jpn. 2004, 77, 195–210. (b) Morimoto, M.; Irie, M. Chem. Commun. 2005, 3895–3905. (c) Irie, M. Proc. Jpn. Acad., Ser. B 2010, 86, 472–483. (d) Irie, M. Photochem. Photobiol. Sci. 2010, 9, 1535–1542. (e) Irie, M.; Kobatake, S.; Horichi, M. Science 2001, 291, 1769–1772. (d) Colombier, I.; Spagnoli, S.; Corval, A.; Baldeck, P. L.; Giraud, M.; Leaustic, A.; Yu, P.; Irie, M. J. Chem. Phys. 2007, 126, 011101. (e) Pu, S.; Liu, G.; Shen, L.; Xu, J. Org. Lett. 2007, 9, 2139–2142. (f) Spangenberg, A.; Metivier, R.; Gonzalez, J.; Nakatani, K.; Yu, P.; Giraud, M.; Leaustic, A.; Guillot, R.; Uwada, T.; Asahi, T. Adv. Mater. 2009, 21, 309–313. (g) Yamaguchi, T.; Taniguchi, W.; Ozeki, T.; Irie, S.; Irie, M. J. Photochem. Photobiol. A. Chem. 2009, 207, 282–287. (13) Uchida, K.; Sukata, S.; Matsuzawa, Y.; Akazawa, M.; de Jong, J. J. D.; Katsonis, N.; Kojima, Y.; Nakamura, S.; Areephong, J.; Meetsma, A.; Feringa, B. L. Chem. Commun. 2008, 326–328. (14) Koshima, H.; Ojima, N.; Uchimoto, H. J. Am. Chem. Soc. 2009, 131, 6890–6891. (15) Kuroki, L.; Takami, S.; Yoza, K.; Morimoto, M.; Irie, M. Photochem. Photobiol. Sci. 2010, 9, 221–225. (16) Morimoto, M.; Irie, M. J. Am. Chem. Soc. 2010, 132, 14172–14178. (17) Kobatake, S.; Matsumoto, Y.; Irie, M. Angew. Chem., Int. Ed. 2005, 44, 2148–2151. (18) (a) Kobatake, S.; Uchida, K.; Tsuchida, E.; Irie, M. Chem. Commun. 2002, 2804–2805. (b) Shibata, K.; Muto, K.; Kobatake, S.; Irie, M. J. Phys. Chem. A 2002, 106, 209–214. (19) Shibata, K.; Kobatake, S.; Irie, M. Chem. Lett. 2001, 618–619. (20) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467–473. (21) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement; Universit€at G€ottingen: G€ottingen, Germany, 1997. (22) Takata, A.; Yokojima, S.; Nakagawa, H.; Matsuzawa, Y.; Murakami, A.; Nakamura, S.; Irie, M.; Uchida, K. J. Phys. Org. Chem. 2007, 20, 998– 1006. (23) (a) Kobatake, S.; Yamada, T.; Uchida, K.; Kato, N.; Irie, M. J. Am. Chem. Soc. 1999, 121, 2380–2386. (b) Kobatake, S.; Yamada, M.; Yamada, T.; Irie, M. J. Am. Chem. Soc. 1999, 121, 8450–8456. (24) The order parameter is apparently lowered because two absorption bands exist in the visible region. The two transition moments are perpendicular each other. Also see ref 23.
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(25) Kobatake, S.; Morimoto, M.; Asano, Y.; Murakami, A.; Nakamura, S.; Irie, M. Chem. Lett. 2002, 1224–1225. (26) The absorption maximum wavelength of 1b in the closed-ring form crystal of 1b showed at ∼670700 nm.
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