Phenanthrothiophene-Triazine Star-Shaped Discotic Liquid Crystals: Synthesis, Self-Assembly, and Stimuli-Responsive Fluorescence Properties

Zeng, Chong Yang; Deng, Wen Jing; Zhao, Ke Qing; Redshaw, Carl; Donnio, Bertrand

Abstract

Lipophilic biphenylthiophene- and phenanthrothiophene-triazine compounds, BPTTn and CPTTn, respectively, were prepared by a tandem procedure involving successive Suzuki-Miyaura coupling and Scholl cyclodehydrogenation reactions. These compounds display photoluminescence in solution and in thin film state, solvatochromism with increasing solvent's polarity, as well as acidochromism and metal ion recognition stimuli-responsive fluorescence. Protonation of BPTT10 and CPTT10 by trifluoroacetic acid results in fluorescence quenching, which is reversibly restored once treated with triethylamine (ON-OFF switch). DFT computational studies show that intramolecular charge transfer (ICT) phenomena occurs for both molecules, and reveal that protonation enhances the electron-withdrawing ability of the triazine core and reduces the band gap. This acidochromic behavior was applied to a prototype fluorescent anti-counterfeiting device. They also specifically recognize Fe3+ through coordination, and the recognition mechanism is closely related to the photoinduced electron transfer between Fe3+ and BPTT10/CPTT10. CPTTn self-assemble into columnar rectangular (Colrec) mesophase, which can be modulated by oleic acid via the formation of a hydrogen-bonded supramolecular liquid crystal hexagonal Colhex mesophase. Finally, CPTTn also form organic gels in alkanes at low critical gel concentration (3.0 mg/mL). Therefore, these star-shaped triazine molecules possess many interesting features and thus hold great promises for information processing, liquid crystal semiconductors and organogelators.

Citation

Zeng, C. Y., Deng, W. J., Zhao, K. Q., Redshaw, C., & Donnio, B. (in press). Phenanthrothiophene-Triazine Star-Shaped Discotic Liquid Crystals: Synthesis, Self-Assembly, and Stimuli-Responsive Fluorescence Properties. Chemistry: a European journal, Article e202400296. https://doi.org/10.1002/chem.202400296

• Journal Article Type: Article
• Acceptance Date: Mar 1, 2024
• Online Publication Date: Mar 22, 2024
• Deposit Date: Apr 7, 2024
• Publicly Available Date: Apr 9, 2024
• Journal: Chemistry - A European Journal
• Print ISSN: 0947-6539
• Electronic ISSN: 1521-3765
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Article Number: e202400296
• DOI: https://doi.org/10.1002/chem.202400296
• Keywords: Triazine; Discotic liquid crystal; Stimuli responsive luminescence; Metal ion recognition; Phenanthrothiophene
• Public URL: https://hull-repository.worktribe.com/output/4614335