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

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.

Influence of Morphology and Common Oxidants on the Photocatalytic Property of ß-SnWO4 Nanoparticles.

In this paper, we report a simple, cost effective and surfactant-free method for synthesizing different morphology of ß-SnWO4 with irregular, spherical, flake-like and leaf-like structures by using sonochemical method followed by calcination. A well dispersed and highly crystalline ß-SnWO4 crystallites with various sizes have been prepared. The samples were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-vis spectroscopy, particle size and Zeta potential analyser. The SEM images reveal the successful preparation of an irregular, spherical, flake-like and leaf-like structure of ß-SnWO4. The absorption maximum of as-prepared different structures of ß-SnWO4 was observed in visible region. The degradation efficiency was found to be increased in leaf-like structures compared to irregular, spherical and flake-like structures of ß-SnWO4. Further, an enhanced photocatalytic effect was observed in leaf-like ß-SnWO4 nanoparticles while the common oxidants such as peroxomonosulphate (PMS), peroxodisulphate (PDS) and hydrogen peroxide (H2O2) were added. The degradation efficiency of these oxidants was found in the order of PMS > H2O2 > PDS. Generally these oxidants act as electron scavengers. From our experimental results, it is found that maximum efficiency of 93% was achieved when PMS was added. This shows the vital role of common oxidants in photocatalytic characteristics and their future applications in waste-water treatment.