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Photochromism of diarylethene molecules and crystals.

Irie M - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

Bottom Line: The thermal irreversibility is an indispensable property for the application of photochromic molecules to optical memories and switches.We have developed a new class of photochromic molecules named "diarylethenes", which show the thermally irreversible photochromic reactivity.The well designed diarylethene derivatives provide outstanding photochromic performance: both isomers are thermally stable for more than 470,000 years, photoinduced coloration/decoloration can be repeated more than 10(5) cycles, the quantum yield of cyclization reaction is close to 1 (100%), and the response times of both coloration and decoloration are less than 10 ps.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, Tokyo, Japan.

ABSTRACT
Photochromism is defined as a reversible transformation of a chemical species between two isomers upon photoirradiation. Although vast numbers of photochromic molecules have been so far reported, photochromic molecules which exhibit thermally irreversible photochromic reactivity are limited to a few examples. The thermal irreversibility is an indispensable property for the application of photochromic molecules to optical memories and switches. We have developed a new class of photochromic molecules named "diarylethenes", which show the thermally irreversible photochromic reactivity. The well designed diarylethene derivatives provide outstanding photochromic performance: both isomers are thermally stable for more than 470,000 years, photoinduced coloration/decoloration can be repeated more than 10(5) cycles, the quantum yield of cyclization reaction is close to 1 (100%), and the response times of both coloration and decoloration are less than 10 ps. This review describes theoretical background of the photochromic reactions, color changes of the derivatives in solution as well as in the single crystalline phase, and application of the crystals to light-driven actuators.

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(a) Chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) (b) absorption spectra of the open- (solid line) and the closed-ring (red line) isomers and (c) top- and side-views of the geometrical structures of the open- and closed-ring isomers.
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fig02: (a) Chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) (b) absorption spectra of the open- (solid line) and the closed-ring (red line) isomers and (c) top- and side-views of the geometrical structures of the open- and closed-ring isomers.

Mentions: A typical example of the electronic and geometrical structural changes of a diarylethene derivative is shown in Fig. 2. Figure 2a and b show the chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) and their absorption spectral changes (color changes).4) In the left-side open-ring isomer two thiophene rings have no interaction and the spectrum is similar to a substituted thiophene. On the other hand, in the right-side closed-ring isomer π-electrons are delocalized throughout the molecule and the HOMO–LUMO gap becomes small. As a result, the spectrum shifts to longer wavelengths. The red-color is ascribed to the delocalization of π-electrons. At the same time, the molecule changes the geometrical structure. The top- and side-views of the molecule are shown in Fig. 2c. As can be seen from the side-view, thickness of the molecule becomes thinner when the molecule undergoes the photocyclization. The top-view of the molecule indicates that the base width of the triangle shape (blue broken line) decreases from 1.01 nm to 0.90 nm and the height increases from 0.49 nm to 0.56 nm. Inferring from the shape change it is concluded that the diarylethene molecule shrinks upon photocyclization and expands upon photocycloreversion.5,6)


Photochromism of diarylethene molecules and crystals.

Irie M - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

(a) Chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) (b) absorption spectra of the open- (solid line) and the closed-ring (red line) isomers and (c) top- and side-views of the geometrical structures of the open- and closed-ring isomers.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108296&req=5

fig02: (a) Chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) (b) absorption spectra of the open- (solid line) and the closed-ring (red line) isomers and (c) top- and side-views of the geometrical structures of the open- and closed-ring isomers.
Mentions: A typical example of the electronic and geometrical structural changes of a diarylethene derivative is shown in Fig. 2. Figure 2a and b show the chemical structures of the open- and the closed-ring isomers of 1,2-bis(2,5-dimethyl-3-theinyl)perfluorocyclopentene (1a) and their absorption spectral changes (color changes).4) In the left-side open-ring isomer two thiophene rings have no interaction and the spectrum is similar to a substituted thiophene. On the other hand, in the right-side closed-ring isomer π-electrons are delocalized throughout the molecule and the HOMO–LUMO gap becomes small. As a result, the spectrum shifts to longer wavelengths. The red-color is ascribed to the delocalization of π-electrons. At the same time, the molecule changes the geometrical structure. The top- and side-views of the molecule are shown in Fig. 2c. As can be seen from the side-view, thickness of the molecule becomes thinner when the molecule undergoes the photocyclization. The top-view of the molecule indicates that the base width of the triangle shape (blue broken line) decreases from 1.01 nm to 0.90 nm and the height increases from 0.49 nm to 0.56 nm. Inferring from the shape change it is concluded that the diarylethene molecule shrinks upon photocyclization and expands upon photocycloreversion.5,6)

Bottom Line: The thermal irreversibility is an indispensable property for the application of photochromic molecules to optical memories and switches.We have developed a new class of photochromic molecules named "diarylethenes", which show the thermally irreversible photochromic reactivity.The well designed diarylethene derivatives provide outstanding photochromic performance: both isomers are thermally stable for more than 470,000 years, photoinduced coloration/decoloration can be repeated more than 10(5) cycles, the quantum yield of cyclization reaction is close to 1 (100%), and the response times of both coloration and decoloration are less than 10 ps.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, Tokyo, Japan.

ABSTRACT
Photochromism is defined as a reversible transformation of a chemical species between two isomers upon photoirradiation. Although vast numbers of photochromic molecules have been so far reported, photochromic molecules which exhibit thermally irreversible photochromic reactivity are limited to a few examples. The thermal irreversibility is an indispensable property for the application of photochromic molecules to optical memories and switches. We have developed a new class of photochromic molecules named "diarylethenes", which show the thermally irreversible photochromic reactivity. The well designed diarylethene derivatives provide outstanding photochromic performance: both isomers are thermally stable for more than 470,000 years, photoinduced coloration/decoloration can be repeated more than 10(5) cycles, the quantum yield of cyclization reaction is close to 1 (100%), and the response times of both coloration and decoloration are less than 10 ps. This review describes theoretical background of the photochromic reactions, color changes of the derivatives in solution as well as in the single crystalline phase, and application of the crystals to light-driven actuators.

Show MeSH
Related in: MedlinePlus