Chapter 14
Photosynergetic Enhancement
of Photosensitivity of Photochromic
Terarylenes
Tsuyoshi Kawai
Abstract Photochromic molecules are one of the major targets of research among
various scopes of photosynergetic approaches on molecular photochemistry. In this
chapter, the authors describe progress of photosynergetic enhancement of photoreactivity of photochromic substances beyond classic photochemical stoichiometry
based on one molecule/one photon hypothesis. Catalytic activity of photoproduct is
one of the key concepts to achieve this and the classic concept of photoacid generators, PAGs, was far expanded for photo-Lewis Acid Generators, PLAGs. Cascade
reactions involving photochromic molecules are further maximized with terarylene
derivatives and amplified radio-chromic nature was rationally demonstrated, opening
critical scope for the future of molecular photochemistry.
Keywords Photochromism · Photosynergetics · Photoisomerization · Terarylene ·
Diarylethene
14.1 Introduction
Photo-induced reactions of various molecules are widely observed in various natural
and artificial systems. Vision systems in monomania are, for example generally based
on the photoisomerization of retinal in the host protein such as opsin [1–3]. One of
their typical properties is their capability for fine tunings on sensitive wavelength and
photochemical sensitivity based on the protein-retinal interaction. Photosensitivity
is a more general figure of merits for most of artificial photoreactive substances and
materials. As the photo-induced reaction of molecules is practically promoted with a
remote way and can be spatially confined in the photo-irradiated area, they are widely
used in industrial photoresist polymer systems and photo-curable resin systems [4].
While biological and medical aspects have become pronounced targets, such as
phototherapy and photopharmacology [5], industrial photoreactive substances are
still considered to be of the most practical and social importance. In these systems,
T. Kawai (B)
Division of Materials Science, Nara Institute of Science and Technology, NAIST, F410-8916-5,
Takayama, Ikoma, Nara 630-0192, Japan
e-mail: tkawai@ms.naist.jp
© 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_14
241
Photosynergetic Enhancement
of Photosensitivity of Photochromic
Terarylenes
Tsuyoshi Kawai
Abstract Photochromic molecules are one of the major targets of research among
various scopes of photosynergetic approaches on molecular photochemistry. In this
chapter, the authors describe progress of photosynergetic enhancement of photoreactivity of photochromic substances beyond classic photochemical stoichiometry
based on one molecule/one photon hypothesis. Catalytic activity of photoproduct is
one of the key concepts to achieve this and the classic concept of photoacid generators, PAGs, was far expanded for photo-Lewis Acid Generators, PLAGs. Cascade
reactions involving photochromic molecules are further maximized with terarylene
derivatives and amplified radio-chromic nature was rationally demonstrated, opening
critical scope for the future of molecular photochemistry.
Keywords Photochromism · Photosynergetics · Photoisomerization · Terarylene ·
Diarylethene
14.1 Introduction
Photo-induced reactions of various molecules are widely observed in various natural
and artificial systems. Vision systems in monomania are, for example generally based
on the photoisomerization of retinal in the host protein such as opsin [1–3]. One of
their typical properties is their capability for fine tunings on sensitive wavelength and
photochemical sensitivity based on the protein-retinal interaction. Photosensitivity
is a more general figure of merits for most of artificial photoreactive substances and
materials. As the photo-induced reaction of molecules is practically promoted with a
remote way and can be spatially confined in the photo-irradiated area, they are widely
used in industrial photoresist polymer systems and photo-curable resin systems [4].
While biological and medical aspects have become pronounced targets, such as
phototherapy and photopharmacology [5], industrial photoreactive substances are
still considered to be of the most practical and social importance. In these systems,
T. Kawai (B)
Division of Materials Science, Nara Institute of Science and Technology, NAIST, F410-8916-5,
Takayama, Ikoma, Nara 630-0192, Japan
e-mail: tkawai@ms.naist.jp
© 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_14
241