Issue 24, 2024

Facile synthesis and characterization of aza-bridged all-benzenoid quinoidal figure-eight and cage molecules

Abstract

Synthesis of conjugated compounds with unusual shape-persistent structures remains a challenge. Herein, utilizing thermodynamically reversible intermolecular Friedel–Crafts alkylation, a dynamic covalent chemistry (DCC) reaction, we facilely synthesized a figure-eight shaped macrocycle FEM and cage molecules CATPA/CACz. X-ray crystallographic analysis confirmed the chemical geometries of tetracation FEM4+(PF6)4 and hexacation CACz6+(SbF6)6. FEM and CATPA displayed higher photoluminescence quantum yield in solid states compared to that in solution, whereas CACz gave the reverse result. DFT calculations showed that fluorescence-related frontier molecular orbital profiles are mainly localized on their arms consisting of a p-quinodimethane (p-QDM) unit and two benzene rings of triphenylamine or carbazole. Owing to their space-confined structures, variable-temperature 1H NMR measurements showed that FEM, CATPA and FEM4+ have intramolecular restricted motion of phenyl rings on their chromophore arms. Accordingly, FEM and CATPA with flexible triphenylamine subunits displayed aggregation-induced emission behavior (AIE), whereas CACz with a rigid carbazole subunits structure showed no AIE behavior.

Graphical abstract: Facile synthesis and characterization of aza-bridged all-benzenoid quinoidal figure-eight and cage molecules

Supplementary files

Article information

Article type
Edge Article
Submitted
29 May 2023
Accepted
27 Apr 2024
First published
31 May 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2024,15, 9087-9095

Facile synthesis and characterization of aza-bridged all-benzenoid quinoidal figure-eight and cage molecules

S. Dong, Y. Han, Z. Tong, J. Wang, Y. Zhang, A. Li, T. Y. Gopalakrishna, H. Tian and C. Chi, Chem. Sci., 2024, 15, 9087 DOI: 10.1039/D3SC02707D

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