Nanotechnologies / Materials
Medical & healthcare, Biosensing

Development of organic molecules with bright circularly
polarized luminescence based on cyclodextrins
Division of Applied Chemistry, Graduate School of Engineering
Associate Professor Hajime Shigemitsu

https://researchmap.jp/hajime_shigemitsu

Professor Toshiyuki Kida

https://researchmap.jp/tkida

Abstract

Nanotechnologies / Materials

Circularly polarized luminescence (CPL) is a phenomenon inwhich the intensity of left- and right-handed rotational luminescence differs during the electronic transition from the excited state
to the ground state in a material with a chiral structure. CPL is
expected to be applied to optical communication technology to ensure security and biosensors to detect chirality. In this research, we
aim at “development of high-brightness CPL organic molecules”
and “CPL biosensing” using them, based on our original molecular
design strategy.

to the development of basic research by deepening the science of“excited state chemistry.

▍ Background & Results
When CPL is applied to biosensing and imaging, it is desirable
to use small organic molecules. However, small molecule-derived
CPL is difficult because of its low luminescence quantum yieldand CPL anisotropy, as well as the need to properly design its
molecular recognition ability. To solve this problem, we designed
and synthesized a molecule (Pyrene-cyclodextrin (PCD)), which
composed of a chiral cyclic oligosaccharide modified with multiple
excimer dyes, based on our original molecular design strategy.
We hypothesized that the multiple pyrene units on the cyclodextrin(CyD) scaffold would form excimer in a restricted space, resulting
in a CPL that exhibits high quantum yield and anisotropy due tosteric hindrance and cumulative interactions. In addition, PCD isexpected to exhibit good focusing properties due to the presenceof multiple pyrene units.
PCD can be easily synthesized in a single step from commercially available starting materials and was found to exhibit a highmolecular absorption coefficient (1.0 × 105 M-1cm-1), polarizedluminescence with a good asymmetry factor (1.2 × 10-2), and aquantum yield (0.39). The CPL brightness of PCD reached 340
M-1cm-1, which is very high among the organic molecules with CPL
activity reported so far and is one of the highest in the world. Theseresults are pioneering achievements that clearly demonstrate thepotential of small organic molecules for CPL biosensing.

Figure 1. Chemical structure and schematic representation of PCD.

Figure 2. CPL sensing of a biomolecule (cholesterol) by PCD.

▍ Significance of the research and Future perspective
CPL is expected to be utilized in a wide range of areas, including next-generation three-dimensional displays, information andcommunication technology, biosensors, advanced security printing, plant growth promotion, and medical diagnostic applications.
Therefore, CPL materials are being actively researched worldwide,
but their development into bio-applications is completely unexplored. The realization of the goals of this research plan, namely,“creation of highly brilliant circularly polarizable organic molecules”
and “biosensing,” is extremely pioneering research that will serve
as a milestone toward the development of next-generation diagnostic and imaging technologies. In addition to these CPL applications, this research is also a world-leading study that contributes

Figure 3. CPL biological applications for diagnosis and elucidation of life phenomena.

P a t e n t Japanese Patent Application No. 2019-56572
Shigemitsu, Hajime; Kawakami, Kosei; Kida, Toshiyuki et al. Cyclodextrins with Multiple Pyrenyl Groups: An Approach to Organic Molecules Exhibiting
Tr e a t i s e
Bright Excimer Circularly Polarized Luminescence. Angew. Chem. Int. Ed. 2022, 61(8), e202114700, doi: 10.1002/anie.202114700
URL
K e y w o r d cyclodextrin, circularly polarized iuminescence, molecular recognition