Fluorescent Sensor Based on 1IH/I-Pyrazolo[3,4-Ib/I]quinoline Derivative for Detecting Zn[sup.2+] Cations

• Published in: Molecules (Basel, Switzerland) Vol. 29; no. 4
• Main Authors: Kolbus, Anna, Uchacz, Tomasz, Danel, Andrzej, Gałczyńska, Katarzyna, Moskwa, Paulina, Kolek, Przemysław
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.02.2024
• Subjects: Fluorescence; Quinoline; Resveratrol; Scientific equipment and supplies industry; Sensors; Zinc compounds; Poland; Switzerland; Germany
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29040823

The photophysical and sensory properties of the donor–acceptor pyrazoloquinoline derivative (PQPc) were investigated using absorption, steady-state, and time-resolved fluorescence measurements. The compound synthesized from commercial, readily available substrates exhibited absorptions in the UV–Vis range, with a maximum of the longwave band around 390 nm. The maximum fluorescence was around 460–480 nm, depending on the solvent. The quantum yield was between 12.87% (for n-hexane) and 0.75% (for acetonitrile) and decreased with increasing solvent polarity. The PET mechanism was implicated as the cause of fluorescence quenching. Divalent ions such as Zn[sup.2+], Pb[sup.2+], Cd[sup.2+], Ca[sup.2+], Mg[sup.2+], Co[sup.2+], Ni[sup.2+], and Cu[sup.2+] were introduced to study the fluorescent response of PQPc. A 13-times increase in fluorescence quantum yield was observed after the addition of Zn[sup.2+] ions. Detailed research was carried out for the PQPc-Zn[sup.2+] system in order to check the possibility of analytical applications of PQPc as a fluorescent sensor. A detection limit of Zn[sup.2+] was set at the value level 1.93 × 10[sup.−7] M. PQPc-Zn[sup.2+] complexes had a stoichiometry of 1:1 with a binding constant of 859 M[sup.−1]. Biological studies showed that the sensor was localized in cells near the membrane and cytoplasm and may be used to detect zinc ions in eukaryotic cells.