A pH-responsive fluorescent sensor based on a new pyranoxanthylium salt

• Type: Article in International Scientific Journal
• Date: 2021

Authors

Gomes, V (Author) Other; Nuno Mateus (Author) FCUP; Victor de Freitas (Author) FCUP; Luis Cruz (Author) FCUP

Journal

Title: Photochemical & Photobiological Sciences

Vol. 20

Pages: 513-521

ISSN: 1474-905X

Publisher: Springer Nature

Indexing

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Other information

Authenticus ID: P-00T-NNS

DOI: 10.1007/s43630-021-00033-x

Abstract (EN): Stimuli-responsive pigments are very interesting for several technological applications, such as food and cosmetic colorants, color-based sensors and fluorescence probes, among others. In this work, the synthesis of a new xanthylium-derived pigment was developed and the chemical and photophysical properties in hydroalcoholic solution at different pH values were investigated by UV-Vis and fluorescence spectroscopy. The UV-Vis titration of 3,6,8-trihydroxy-11-methylpyranoxanthylium has shown four different colored chemical species (Delta H+, A, A(-) and A(2-)) in hydroalcoholic solution in a pH range between 1 and 12 with the thermodynamic acidic constants of pK(a1) =4.80 +/- 0.03, pK(a2) = 6.51 +/- 0.05 and pK(a3) = 8.64 +/- 0.01. Regarding fluorescence properties, this dye revealed an interesting pH-dependent emission behavior. In fact, the anionic quinoidal base A - predominant at pH range between 5 and 9 should be mainly responsible for the pronounced fluorescence intensity observed at lambda(ex) 467 nm/lambda(em) 510 nm pair (maximum at pH 7.5). This set of new insights make this dye useful as a potential "off-on-off" pH-responsive fluorescent probe for biological applications. [GRAPHICS] .

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9