Issue 12, 2023

3,4-Ethylenedithio thiophene donor for NIR-II fluorophores with improved quantum yields

Abstract

Bright fluorophores are vital for bioimaging in the second near-infrared (NIR-II, 1500–1700 nm) window. Donor engineering has been demonstrated to be effective at significantly improving the brightness of donor–acceptor–donor (D–A–D) NIR-II fluorophores. Developing new donor units to construct NIR-II fluorophores with improved quantum yields (QYs) is still challenging. Herein, 3,4-ethylenedithio thiophene (EDST) is employed as the donor unit for the first time to construct a new NIR-II fluorophore, IR-nFES. Compared with the fluorophore IR-nFE with the 3,4-ethylenedioxy thiophene (EDOT) donor, sulphur atom replacement can significantly increase the conjugation backbone distortion, affording an enhanced fluorescence QY of 5.5% in toluene for IR-nFES. Water soluble nanofluorophores (NFs) of IR-nFES are fabricated by encapsulating with an amphiphilic copolymer, and IR-nFE NFs show a QY of 1.3%, 4.8 times higher than that of the IR-nFE counterpart. It is further demonstrated that IR-nFES NFs are significantly brighter than IR-nFE NFs and indocyanine green (ICG), and also exhibit good optical stability. Consequently, IR-nFES NFs realize superior in vivo imaging of mouse cerebral vessels with a high signal-to-background ratio (SBR) of 4.99. Our studies reveal that sulphur substitution can afford new NIR-II molecular fluorophores with enhanced brightness.

Graphical abstract: 3,4-Ethylenedithio thiophene donor for NIR-II fluorophores with improved quantum yields

Supplementary files

Article information

Article type
Research Article
Submitted
13 Dec 2022
Accepted
17 Mar 2023
First published
18 Mar 2023

Mater. Chem. Front., 2023,7, 2419-2425

3,4-Ethylenedithio thiophene donor for NIR-II fluorophores with improved quantum yields

C. Liu, X. Wang, X. Zhu, R. Ma, Q. Lin and Y. Liang, Mater. Chem. Front., 2023, 7, 2419 DOI: 10.1039/D2QM01278B

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