Issue 5, 2022

Reaction induced supramolecular gelation with the evolution of circularly polarized luminescence

Abstract

Chemical reaction-guided supramolecular gelation has been attracting attention due to its dynamic response and adaptability. We demonstrated here that the direct reduction of the C[double bond, length as m-dash]N bond to a C–N bond by NaBH4 caused sol-to-gel and gel-to-gel transitions of amphiphilic Schiff bases. 1-Hydroxy-1-naphthaldehyde or 2-hydroxy-1-naphthaldehyde was reacted with an amine-terminated dialkyl glutamide amphiphile (LG) to afford Schiff base 1-NLG or 2-NLG, respectively. These amphiphilic Schiff bases couldn’t self-assemble into supramolecular gels in ethanol, while the introduction of NaBH4 led to the formation of a supramolecular gel constituted by 2-NLG via reducing the imine to a secondary amine group. It was worth noting that 2-NLG was non-fluorescent due to the occurrence of excited-state intramolecular proton transfer (ESIPT). Interestingly, as the reduction reaction proceeded, the emission of 2-NLG was enhanced and it emitted green fluorescence, and then the green fluorescence emitted by the 2-NLG gel gradually turned into a blue emission. In contrast, only an enhanced blue emission was observed in the case of the 1-NLG assembly upon reduction, instead of sol-to-gel transitions. Accompanied by the formation of a supramolecular gel, the circularly polarized luminescence (CPL) of 2-NLG was also observed, whose colour evolved from green to blue. Furthermore, when 8-hydroxy-1,3,6-pyrenetrisulfonate (HPTS) was doped into the 2-NLG system, both an enhanced emission and an amplified CPL signal of HPTS were found upon the formation of the supramolecular co-gel. This work provided an attractive strategy for fabricating dynamic adaptable soft materials with amplified CPL signals.

Graphical abstract: Reaction induced supramolecular gelation with the evolution of circularly polarized luminescence

Supplementary files

Article information

Article type
Research Article
Submitted
25 12 2021
Accepted
06 1 2022
First published
09 1 2022

Mater. Chem. Front., 2022,6, 593-599

Reaction induced supramolecular gelation with the evolution of circularly polarized luminescence

K. Li, S. Chen, X. Zhu, H. Fan, L. Zhang and M. Liu, Mater. Chem. Front., 2022, 6, 593 DOI: 10.1039/D1QM01654G

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