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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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AFM images of the (100) surface of single crystal 22a (a) before and (b) after irradiation with 365 nm light and (c) after irradiation with visible (λ > 500 nm) light.
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fig11: AFM images of the (100) surface of single crystal 22a (a) before and (b) after irradiation with 365 nm light and (c) after irradiation with visible (λ > 500 nm) light.

Mentions: We carried out AFM measurement of the single crystal of 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocycopentene (22a).35) The surface morphology change was followed before and after UV (365 nm) irradiation and after visible (>500 nm) irradiation. Figure 11 shows the AFM images. Upon irradiation for more than 10 s with UV light, steps appeared on the (100) surface. No step formation was discerned during the irradiation for the initial 10 s but appeared after the induction period. The step height is 1.0 nm. The step disappeared by irradiation with visible light. When the irradiation time was prolonged, the number of steps increased and steps with height of 2.0 and 3.0 nm appeared. The height was always multiples of the minimum step height of 1.0 nm, which corresponds to one molecular layer. The morphological change was reversible and correlated with the color change. This result indicates that the change of molecular shape is linked to macro-scale shape of materials in the densely packed crystal. In densely packed crystalline systems the strain energy generated by the molecular shape change directly influences the shape of the bulk crystal. Based on this view we prepared small-size single crystals (10–100 µm) of photochromic diarylethenes and demonstrated that the bulk shape of crystals changes upon photoirradiation.11)


Photochromism of diarylethene molecules and crystals.

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

AFM images of the (100) surface of single crystal 22a (a) before and (b) after irradiation with 365 nm light and (c) after irradiation with visible (λ > 500 nm) light.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig11: AFM images of the (100) surface of single crystal 22a (a) before and (b) after irradiation with 365 nm light and (c) after irradiation with visible (λ > 500 nm) light.
Mentions: We carried out AFM measurement of the single crystal of 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocycopentene (22a).35) The surface morphology change was followed before and after UV (365 nm) irradiation and after visible (>500 nm) irradiation. Figure 11 shows the AFM images. Upon irradiation for more than 10 s with UV light, steps appeared on the (100) surface. No step formation was discerned during the irradiation for the initial 10 s but appeared after the induction period. The step height is 1.0 nm. The step disappeared by irradiation with visible light. When the irradiation time was prolonged, the number of steps increased and steps with height of 2.0 and 3.0 nm appeared. The height was always multiples of the minimum step height of 1.0 nm, which corresponds to one molecular layer. The morphological change was reversible and correlated with the color change. This result indicates that the change of molecular shape is linked to macro-scale shape of materials in the densely packed crystal. In densely packed crystalline systems the strain energy generated by the molecular shape change directly influences the shape of the bulk crystal. Based on this view we prepared small-size single crystals (10–100 µm) of photochromic diarylethenes and demonstrated that the bulk shape of crystals changes upon photoirradiation.11)

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