Naphthyridine derived colorimetric and fluorescent turn off sensors for Ni2+ in aqueous media

• Published in: Scientific reports Vol. 11; no. 1; p. 19242
• Main Authors: Ashraf, Abida, Islam, Muhammad, Khalid, Muhammad, Davis, Anthony P., Ahsan, Muhammad Tayyeb, Yaqub, Muhammad, Syed, Asad, Elgorban, Abdallah M., Bahkali, Ali H., Shafiq, Zahid
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28-09-2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638; 704/172; 704/4111; Aqueous solutions; Binding sites; Chemical sensors; Color; Colorimetry; Detection limits; Drinking water; Fluorescence; Humanities and Social Sciences; Ligands; multidisciplinary; Science; Science (multidisciplinary); Scientific imaging; Selective media; Sensors; Stoichiometry; Water analysis; Water sampling
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-98400-2

Highly selective and sensitive 2,7-naphthyridine based colorimetric and fluorescence “Turn Off” chemosensors (L1-L4) for detection of Ni
2+
in aqueous media are reported. The receptors (L1-L4) showed a distinct color change from yellow to red by addition of Ni
2+
with spectral changes in bands at 535–550 nm. The changes are reversible and pH independent. The detection limits for Ni
2+
by (L1-L4) are in the range of 0.2–0.5 µM by UV–Visible data and 0.040–0.47 µM by fluorescence data, which is lower than the permissible value of Ni
2+
(1.2 µM) in drinking water defined by EPA. The binding stoichiometries of L1-L4 for Ni
2+
were found to be 2:1 through Job’s plot and ESI–MS analysis. Moreover the receptors can be used to quantify Ni
2+
in real water samples. Formation of test strips by the dip-stick method increases the practical applicability of the Ni
2+
test for “in-the-field” measurements. DFT calculations and AIM analyses supported the experimentally determined 2:1 stoichiometries of complexation. TD-DFT calculations were performed which showed slightly decreased FMO energy gaps due to ligand–metal charge transfer (LMCT).