Cyclodextrins with Multiple Pyrenyl Groups: An Approach to Organic Molecules Exhibiting Bright Excimer Circularly Polarized Luminescence

Hajime Shigemitsu; Kosei Kawakami; Yuuya Nagata; Rikuo Kajiwara; Shintaro Yamada; Tadashi Mori; Toshiyuki Kida

doi:10.1002/anie.202114700

Cyclodextrins with Multiple Pyrenyl Groups: An Approach to Organic Molecules Exhibiting Bright Excimer Circularly Polarized Luminescence

Angew Chem Int Ed Engl. 2022 Feb 14;61(8):e202114700. doi: 10.1002/anie.202114700. Epub 2021 Dec 29.

Authors

Hajime Shigemitsu^{1

2

3

4}, Kosei Kawakami¹, Yuuya Nagata⁵, Rikuo Kajiwara¹, Shintaro Yamada¹, Tadashi Mori¹, Toshiyuki Kida^{1

4}

Affiliations

¹ Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, 565-0871, Japan.
² Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, 565-0871, Japan.
³ Global Center for Medical Engineering and Informatics, Osaka University, 2-1 Yamadaoka, Suita, 565-0871, Japan.
⁴ Integrated Frontier Research for Medical Science Division, Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Japan.
⁵ Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Nishi 10, Kita, Sapporo, 001-0021, Japan.

PMID: 34783445
DOI: 10.1002/anie.202114700

Abstract

We report a simple and effective approach to organic molecules exhibiting bright circularly polarized luminescence (CPL) by combining a chiral cyclic molecular scaffold and multiple excimer-enabling moieties. An α-cyclodextrin (CyD) scaffold was modified with six pyrenyl groups to obtain pyrene-cyclodextrins (PCDs) in a one-step synthesis from commercially available compounds. The PCDs exhibited high molar extinction coefficients (ϵ≈10⁵ M^-1 cm^-1 ), polarized emission with a good dissymmetry factor (|g_lum |≈10^-2 ), and quantum yield (Φ_f ≈0.5). Owing to the excellent photophysical properties of the PCDs, the circularly polarized luminescence brightness (B_CPL ) reached 340 M^-1 cm^-1 . Photophysical and chiroptical studies of the PCDs with only five pyrene units and with linkers of various lengths connecting the CyD with the pyrene units revealed that the formation of a pyrene excimer in a spatially crowded environment is crucial for CPL anisotropy. This study paves the way for the development of bright CPL organic molecules.

Keywords: brightness; circularly polarized luminescence; cyclodextrin; pyrene excimer.

Publication types

Research Support, Non-U.S. Gov't