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We reported that C8[12]DBA, a C3-symmetric hexadecahydrotribenzo[12]annulene ([12]DBA) with a pore surrounded by three −C≡C− bonds, forms a stable molecular glass during cooling from the liquid state when an octylbenzoate group was introduced at the molecular terminal. In this study, to understand the influence of the molecular structure of C3-symmetric DBA derivatives on molecular assembly structures and optical properties, we newly synthesized C8[18]DBA, which has a pore surrounded by more elongated −C≡C−C≡C− bonds. Furthermore, a comparison was made with an octylbenzoate-substituted triphenylene derivative (C8Trip) that has C3 symmetry and no pore at the molecular center. The strength of intermolecular interactions decreased in the order C8[18]DBA > C8Trip > C8[12]DBA. C8[18]DBA formed π-dimers and gave crystalline molecular assemblies, whereas in C8[12]DBA, the suppression of π-π interactions stabilized the glass state. C8[18]DBA did not exhibit dielectric anomalies, whereas C8Trip and C8[12]DBA showed dielectric relaxation associated with the thermal motion of the octyl ester chains. Furthermore, while C8[12]DBA exhibited similar fluorescence spectra in solution and solid states, both C8[18]DBA and C8Trip exhibited aggregation-induced quenching with a significant decrease in fluorescence intensity in the solid state.

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  This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry B, copyright © 2025 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcb.5c04027.

Keyword: Molecular assembly structures, Molecular glass, Dielectric properties, Optical properties, Ring-size effect

Date published: 2025-08-21

Publisher: American Chemical Society (ACS)

Journal:

• The Journal of Physical Chemistry B (ISSN: 15205207) vol. 129 issue. 33 p. 8603-8614

Funding:

• Japan Science and Technology Corporation JPMJAX23DF
• Japan Science and Technology Corporation JPMJFS2102
• Izumi Science and Technology Foundation
• Support for Pioneering Research Initiated by the Next Generation JPMJSP2114
• Japan Society for the Promotion of Science JP20H05865
• Japan Society for the Promotion of Science JP23K13715
• Japan Society for the Promotion of Science JP24K01475
• Ministry of Education, Culture, Sports, Science and Technology
• Japan Society for the Promotion of Science JP24H01727
• Japan Society for the Promotion of Science JP24K01452
• Japan Society for the Promotion of Science JP24K01468

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5663

First published URL: https://doi.org/10.1021/acs.jpcb.5c04027

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Updated at: 2026-02-14 22:09:53 +0900

Published on MDR: 2026-08-05 08:28:55 +0900