Quinoline based reversible fluorescent probe for Pb2+; applications in milk, bioimaging and INHIBIT molecular logic gate

• Published in: Food chemistry Vol. 348; p. 129098
• Main Authors: Velmurugan, K., Vickram, R., Jipsa, C.V., Karthick, R., Prabakaran, G., Suresh, S., Prabhu, J., Velraj, G., Tang, L., Nandhakumar, R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30-06-2021
• Subjects: Bioimaging; Fluorescence; ICT; Lead; Milk detection; Quinoline; Quinoline; Lead; Fluorescence; Milk detection; Bioimaging; ICT
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2021.129098

•Structure of quinoline-Morpholine Conjugate (QMC) was confirmed by Single Crystal X-ray diffraction analysis.•Probe QMC selectively detects Pb2+ ion via intramolecular charge transfer (ICT) and blocking of CN isomerization process.•Limit of detection (LOD) of QMC with Pb2+ downs to 13 μM.•Sensing mechanism of QMC with Pb2+ was applied into milk, red wine, living cells and logic gates.
We report the modular design and synthesis of an amine dangled Schiff base quinoline–morpholine conjugate (QMC) for highly selective detection of Pb2+ ions via fluorimetry. The sensing strategy of QMC towards Pb2+ ion exhibits a large blue shift with fluorescent enhancement via the intramolecular charge transfer (ICT) process. At the same time, QMC coordination with Pb2+, the CN single bond rotation between quinoline and morpholine rings and the CN isomerization process were blocked. Best of our knowledge, this is the first blue shifted turn-on fluorescent chemosensor for Pb2+ ion via the ICT process. Furthermore, QMC selectively detects Pb2+ ion without any interference with alkali, alkaline earth, and transition metal ions, and limit of detection (LOD) downs to 13 μM, which is a permissible level of Pb2+ ion in drinking water reported by WHO. The 1:2 binding stoichiometry between QMC and Pb2+ was confirmed by fluorimetric, 1H NMR titration, mass spectrometry, and theoretical studies. Finally, QMC was potentially applied for the sensing of Pb2+ ions in milk, red wine, live cells and an INHIBIT molecular logic function was constructed by using Pb2+ and EDTA as chemical inputs.