Metal ions recognition by pyrene labeled poly(acrylic acid)

• Published in: Journal of molecular liquids 2022-11, Vol.365, p.120135, Article 120135
• Main Authors: Stîngă, Gabriela, Băran, Adriana, Iovescu, Alina, Maxim, Monica Elisabeta, Anghel, Dan-Florin
• Format: Article
• Language: English
• Subjects: Fluorescent sensor; Metal ions; Pyrene labeled poly(acrylic acid)
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.120135

•The pyrene labeled poly(acrylic acid) (PAA25Py3) was proposed as fluorescent sensor for metal ions.•The Ag+, Cu2+ and Fe3+ statically quenched the pyrene fluorescence.•The PAA25Py3 showed higher sensitivity, selectivity and binding ability for Fe3+ than Cu2+ and Ag+.•The detection limits for Ag+, Cu2+ and Fe3+ were 4.28 × 10−4 M, 1.20 × 10−5 M and 3.90 × 10−6 M, respectively. In the present work, we assessed the sensing of multiple transition metal ions (Men+) using pyrene labeled poly(acrylic acid) (PAA25Py3). The UV–vis, steady-state (excitation and emission) and time-resolved fluorescence as well as FTIR measurements were performed. The comparative effect of Ag+, Cu2+ and Fe3+ on the optical properties (the monomer and excimer maximum intensity, the polarity/conformational index as well as the fluorescence quantum yield and lifetime) of the pyrene (Py) label was evaluated. The influence of the other metal ions (i.e., Li+, K+, Na+, Ba2+, Ca2+, Zn2+, Ni2+ and Al3+) on the Py photophysics was investigated. The fluorescence quenching of both Py monomer and excimer by appropriate amounts of Ag+, Cu2+ and Fe3+ was revealed. The quenching curves of Py were analyzed with the Stern-Volmer equation. The detection limit, the quenching and the binding constants were calculated. The fluorescent polymer showed higher sensitivity, selectivity and binding ability for Fe3+ than Cu2+ and Ag+. It was revealed the occurrence of the electron transfer from the amide group of PAA25Py3 to Py label, the formation of coordination complexes between several Cu2+/Fe3+ ions and carboxylic units of PAA25Py3 as well as the photoinduced electron transfer from excited Py to complexed Men+. The results proved that the pyrene labeled poly(acrylic acid) can be used as a potential fluorescent sensor to detect both Fe3+ and Cu2+ ions.