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. 2022 Jan;32(1):307-318.
doi: 10.1007/s10895-021-02842-w. Epub 2021 Nov 17.

Aesculetin Exhibits Strong Fluorescent Photoacid Character

Authors Leah H Knoor  1 , George R Du Laney  1 , Isaac B Jonker  1 , Liam P Hoogewerf  1 , Yukun Tu  1 , Hunter T Pham  1 , Joy Yoo  1 , Mark A Muyskens  2
Affiliations

Aesculetin Exhibits Strong Fluorescent Photoacid Character

Authors Leah H Knoor et al. J Fluoresc. 2022 Jan.

Abstract

Coumarins are bioactive molecules that often serve as defenses in plant and animal systems, and understanding their fundamental behavior is essential for understanding their bioactivity. Aesculetin (6,7-dihydroxycoumarin) has recently attracted attention due to its ability to act as an antioxidant, but little is known about its photophysical properties. The fluorescence lifetimes of its neutral and anion form in water are 19 ± 2 ps and 2.3 ± 0.1 ns, respectively. Assuming the short lifetime of the neutral is determined by ESPT, we estimate kPT ~ 5 × 1010 s-1. Using steady-state and time-resolved fluorescence spectroscopy, we determine its ground and excited-state [Formula: see text] to be 7.3 and -1, respectively, making it one of the strongest photoacids of the natural coumarins. Aesculetin exhibits a strong pH dependence of the relative fluorescence quantum yield becoming much more fluorescent above [Formula: see text]. The aesculetin anion [Formula: see text] slightly photobasic character. We also report that aesculetin forms a fluorescent catechol-like complex with boric acid, and this complex has a [Formula: see text] of 5.6.

Keywords: Fluorescence spectroscopy; Lifetime; Photoacid; Quantum yield; Stokes shift.

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References

    1. Pruccoli L, Morroni F, Sita G et al (2020) Esculetin as a Bifunctional Antioxidant Prevents and Counteracts the Oxidative Stress and Neuronal Death Induced by Amyloid Protein in SH-SY5Y Cells. Antioxid 9:551. https://doi.org/10.3390/antiox9060551 - DOI
    1. Dong Y, Hou Q, Sun M et al (2020) Targeted Isolation of Antioxidant Constituents from Plantago asiatica L. and In Vitro Activity Assay. Molecules 25:1825. https://doi.org/10.3390/molecules25081825
    1. Cao D, Liu Z, Verwilst P et al (2019) Coumarin-Based Small-Molecule Fluorescent Chemosensors. Chem Rev 119:10403–10519. https://doi.org/10.1021/acs.chemrev.9b00145 - DOI - PubMed
    1. Zhang H-Y, Wang L-F (2004) Theoretical elucidation of structure–activity relationship for coumarins to scavenge peroxyl radical. J Mol Struct THEOCHEM 673:199–202. https://doi.org/10.1016/j.theochem.2003.12.014 - DOI
    1. Signore G, Nifosì R, Albertazzi L et al (2010) Polarity-Sensitive Coumarins Tailored to Live Cell Imaging. J Am Chem Soc 132:1276–1288. https://doi.org/10.1021/ja9050444 - DOI - PubMed

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