Chapter 8
Photo-Switching of Circularly Polarized
Luminescence
Takuya Nakashima and Tsuyoshi Kawai
Abstract Circularly polarized luminescence (CPL) emission from chiral molecular
systems is readily switched by means of external stimuli such as temperature,
solvent, chemicals, and light irradiation. Since CPL is one of the emission phenomena, it can be modulated in a similar manner to the emission switching. The ON-OFF
switching of emission intensity of chiral molecular systems may simply lead to the
modulation of CPL intensity. Apart from the modulation of emission intensity, the
chiral structures including chiral arrangement of fluorophores or metal coordination
geometries are switched by external stimuli, changing the dissymmetry factors, i.e.,
the quality of CPL. In this chapter, we review the design of chiroptical photoswitches based on photochromic molecules that modulate the CPL property in
response to photo-irradiation in a dynamic manner.
8.1 Introduction
The CPL technique is expected to find potential applications in sensors, display, and
advanced information technologies including anti-counterfeiting labeling. Recent
research has made efforts in the manipulation and modulation of CPL activity to
further develop these technologies including supramolecular approaches [1–
11]. High-speed switching of CPL in a dynamic manner by external stimuli should
be of particular interest for the application in cryptographic communication as a
technology for information security [12–14]. Light is one of the external inputs for
various practical applications, whereby one can control the physico-chemical properties of active materials with precise spatiotemporal control in a remote and
noninvasive manner. In this context, chiroptical photo-switches are promising materials for the dynamic modulation of CPL property with imparting luminescent
capability to photo-responsive molecules [15]. Photo-switching of luminescent
T. Nakashima (*) · T. Kawai (*)
Division of Materials Science, Graduate School of Science and Technology, Nara Institute of
Science and Technology, Ikoma, Nara, Japan
e-mail: ntaku@ms.naist.jp; tkawai@ms.naist.jp
© Springer Nature Singapore Pte Ltd. 2020
T. Mori (ed.), Circularly Polarized Luminescence of Isolated Small Organic
Molecules, https://doi.org/10.1007/978-981-15-2309-0_8
177
Photo-Switching of Circularly Polarized
Luminescence
Takuya Nakashima and Tsuyoshi Kawai
Abstract Circularly polarized luminescence (CPL) emission from chiral molecular
systems is readily switched by means of external stimuli such as temperature,
solvent, chemicals, and light irradiation. Since CPL is one of the emission phenomena, it can be modulated in a similar manner to the emission switching. The ON-OFF
switching of emission intensity of chiral molecular systems may simply lead to the
modulation of CPL intensity. Apart from the modulation of emission intensity, the
chiral structures including chiral arrangement of fluorophores or metal coordination
geometries are switched by external stimuli, changing the dissymmetry factors, i.e.,
the quality of CPL. In this chapter, we review the design of chiroptical photoswitches based on photochromic molecules that modulate the CPL property in
response to photo-irradiation in a dynamic manner.
8.1 Introduction
The CPL technique is expected to find potential applications in sensors, display, and
advanced information technologies including anti-counterfeiting labeling. Recent
research has made efforts in the manipulation and modulation of CPL activity to
further develop these technologies including supramolecular approaches [1–
11]. High-speed switching of CPL in a dynamic manner by external stimuli should
be of particular interest for the application in cryptographic communication as a
technology for information security [12–14]. Light is one of the external inputs for
various practical applications, whereby one can control the physico-chemical properties of active materials with precise spatiotemporal control in a remote and
noninvasive manner. In this context, chiroptical photo-switches are promising materials for the dynamic modulation of CPL property with imparting luminescent
capability to photo-responsive molecules [15]. Photo-switching of luminescent
T. Nakashima (*) · T. Kawai (*)
Division of Materials Science, Graduate School of Science and Technology, Nara Institute of
Science and Technology, Ikoma, Nara, Japan
e-mail: ntaku@ms.naist.jp; tkawai@ms.naist.jp
© Springer Nature Singapore Pte Ltd. 2020
T. Mori (ed.), Circularly Polarized Luminescence of Isolated Small Organic
Molecules, https://doi.org/10.1007/978-981-15-2309-0_8
177