Issue 6, 2024

Organic fluorophore-substituted polyaza-[7]helicenes derived from 1,10-phenanthroline: Studying the chromophoric effect on fluorescence efficiency

Abstract

We report a series of fluorescent “push–pull” helicenes based on aza-[7]helicenes denoted as AZA-FLU, AZA-NPC, AZA-TPA, and AZA-2OMe for the control of the excited-state dynamics and circular dichroism properties of parent aza-[7]helicene. These symmetrical materials consist of an aza-[7]helicene central unit acting as an acceptor, which is covalently linked with different donor units, such as fluorene, N-phenyl carbazole, triphenylamine, and N,N-dimethoxy triphenylamine, and induces a strong “push–pull” character. Optoelectronic and electron distribution properties are briefly discussed in terms of electrochemical measurements and theoretical calculations. As compared to parent aza-[7]helicene (ϕ = 39% in neutral media), AZA-NPC shows a higher fluorescence quantum yield (ϕ = 71%) and fluorescence lifetime (τ2 = 15.5 ns) due to the strong donating and intramolecular charge transport properties of the N-phenyl carbazole unit. Further, the basic nature of all aza-[7]helicenes was analyzed via acid titration with trifluoroacetic acid. Among them, AZA-NPC showed a significant change in photophysical properties, indicating a high basic nature due to the strong electron donor behavior of the N-phenyl carbazole unit.

Graphical abstract: Organic fluorophore-substituted polyaza-[7]helicenes derived from 1,10-phenanthroline: Studying the chromophoric effect on fluorescence efficiency

Supplementary files

Article information

Article type
Paper
Submitted
23 Nov 2023
Accepted
03 Jan 2024
First published
04 Jan 2024
This article is Open Access
Creative Commons BY-NC license

Mater. Adv., 2024,5, 2328-2334

Organic fluorophore-substituted polyaza-[7]helicenes derived from 1,10-phenanthroline: Studying the chromophoric effect on fluorescence efficiency

B. Yadagiri, V. Kumar and S. P. Singh, Mater. Adv., 2024, 5, 2328 DOI: 10.1039/D3MA01045G

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