Charge-Segregated Stacking Structure with Anisotropic Electric Conductivity in NIR-Absorbing and Emitting Positively Charged π-Electronic Systems

Kazuhisa Yamasumi; Kentaro Ueda; Yohei Haketa; Yusuke Hattori; Masayuki Suda; Shu Seki; Hayato Sakai; Taku Hasobe; Ryoya Ikemura; Yoshitane Imai; Yukihide Ishibashi; Tsuyoshi Asahi; Kazuto Nakamura; Hiromitsu Maeda

doi:10.1002/anie.202216013

Charge-Segregated Stacking Structure with Anisotropic Electric Conductivity in NIR-Absorbing and Emitting Positively Charged π-Electronic Systems

Angew Chem Int Ed Engl. 2023 Feb 13;62(8):e202216013. doi: 10.1002/anie.202216013. Epub 2023 Jan 17.

Authors

Affiliations

¹ Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan.
² Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan.
³ Department of Chemistry, Faculty of Science and Technology, Keio University, Yokohama, 223-8522, Japan.
⁴ Department of Applied Chemistry, Faculty of Science and Engineering, Kindai University, Higashi, Osaka, 577-8502, Japan.
⁵ Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, Matsuyama, 790-8577, Japan.
⁶ Yokkaichi Research Center, JSR Corporation, Yokkaichi, 510-8552, Japan.

PMID: 36573653
DOI: 10.1002/anie.202216013

Abstract

Squarylium-based π-electronic cation with an augmented dipole was synthesized by methylation of zwitterionic squarylium. The cation formed various ion pairs in combination with anions, and the ion pairs exhibited distinct photophysical properties in the dispersed state, ascribed to the formation of J- and H-aggregates. The ion pairs provided solid-state assemblies based on cation stacking. It is noteworthy that complete segregation of cations and anions was observed in a pseudo-polymorph of the ion pair with pentacyanocyclopentadienide as a π-electronic anion. In the crystalline state, the ion pairs exhibited photophysical properties and electric conductivity derived from cation stacking. In particular, the charge-segregated ion-pairing assembly induces an electric conductive pathway along the stacking axis. The charge-segregated mode and fascinating properties were derived from the reduced electrostatic repulsion between adjacent π-electronic cations via dipole-dipole interactions.

Keywords: Charged π-Electronic Systems; Chiroptical Properties; Electric Conductivity; Ion-Pairing Assemblies; NIR Dyes.

Abstract

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