Chapter 34
Crystallization Control
of the Photoresponsible Diarylethene
Film with an Aluminum Plasmonic Chip
Keiko Tawa, Taiga Kadoyama, Ryo Nishimura, and Kingo Uchida
Abstract The photoisomerization between an open-ring isomer (1o) and a closedring one (1c) in diarylethene 1 film and the needle-shaped microcrystal growth subsequent to photoisomerization were in situ measured with an optical microscope. The
1o film was exposed to UV light on the stage of an upright-inverted microscope
and optical and spectroscopic images were in situ observed in order to clarify the
mechanism of microcrystal growth in the film. 1o films were prepared on a glass
slide and an aluminum (Al) plasmonic chip, which is the Al-coated substrate with a
wavelength-size periodic pattern and can provide the enhanced electric field to the
chip surface. A plasmonic chip was expected to promote a photoisomerization and a
microcrystal growth. Crystal growth of needle-shaped crystal of 1c was observed at
the center of a film under the UV irradiation from upright side, but not observed under
irradiation from inverted side. On the other hand, crystal growth was found at the
film edge by the UV exposure even from the inverted side. Therefore, a high mobility
of 1c molecules near the film surface or edge is essential for crystal growth of 1c.
Further, alignment of 1c molecules also requires the platform of 1o. The conversion
rate from 1o to 1c was larger on the Al grating. By the plasmonic enhanced electric
field, when the attenuated UV light was exposed to the film edge from inverted side,
the needle-shaped crystals were observed only inside the grating at the conversion
rate above 60%. Conversion rate to 1c controlled crystal growth and therefore, crystal
growth was promoted inside the grating. In summary, the conversion rate to 1c above
60%, a mobility of 1c near the film surface or edge, and the 1o underlayer platform
are required for crystal growth after 1c alignment.
Keywords Diarylethene · Spectroscopic imaging · In situ microscopic imaging ·
Cyclization · Crystal growth · Plasmon field
K. Tawa (B) · T. Kadoyama
Department of Applied Chemistry for Environment, School of Science and Technology, Kwansei
Gakuin University, Sanda, Hyogo 669-1337, Japan
e-mail: ktawa@kwansei.ac.jp
R. Nishimura · K. Uchida
Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University,
Seta, Shiga, Japan
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_34
581
Crystallization Control
of the Photoresponsible Diarylethene
Film with an Aluminum Plasmonic Chip
Keiko Tawa, Taiga Kadoyama, Ryo Nishimura, and Kingo Uchida
Abstract The photoisomerization between an open-ring isomer (1o) and a closedring one (1c) in diarylethene 1 film and the needle-shaped microcrystal growth subsequent to photoisomerization were in situ measured with an optical microscope. The
1o film was exposed to UV light on the stage of an upright-inverted microscope
and optical and spectroscopic images were in situ observed in order to clarify the
mechanism of microcrystal growth in the film. 1o films were prepared on a glass
slide and an aluminum (Al) plasmonic chip, which is the Al-coated substrate with a
wavelength-size periodic pattern and can provide the enhanced electric field to the
chip surface. A plasmonic chip was expected to promote a photoisomerization and a
microcrystal growth. Crystal growth of needle-shaped crystal of 1c was observed at
the center of a film under the UV irradiation from upright side, but not observed under
irradiation from inverted side. On the other hand, crystal growth was found at the
film edge by the UV exposure even from the inverted side. Therefore, a high mobility
of 1c molecules near the film surface or edge is essential for crystal growth of 1c.
Further, alignment of 1c molecules also requires the platform of 1o. The conversion
rate from 1o to 1c was larger on the Al grating. By the plasmonic enhanced electric
field, when the attenuated UV light was exposed to the film edge from inverted side,
the needle-shaped crystals were observed only inside the grating at the conversion
rate above 60%. Conversion rate to 1c controlled crystal growth and therefore, crystal
growth was promoted inside the grating. In summary, the conversion rate to 1c above
60%, a mobility of 1c near the film surface or edge, and the 1o underlayer platform
are required for crystal growth after 1c alignment.
Keywords Diarylethene · Spectroscopic imaging · In situ microscopic imaging ·
Cyclization · Crystal growth · Plasmon field
K. Tawa (B) · T. Kadoyama
Department of Applied Chemistry for Environment, School of Science and Technology, Kwansei
Gakuin University, Sanda, Hyogo 669-1337, Japan
e-mail: ktawa@kwansei.ac.jp
R. Nishimura · K. Uchida
Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University,
Seta, Shiga, Japan
© Springer Nature Singapore Pte Ltd. 2020
H. Miyasaka et al. (eds.), Photosynergetic Responses in Molecules
and Molecular Aggregates, https://doi.org/10.1007/978-981-15-5451-3_34
581