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[Display omitted] • PET based Probe 7 showed selectivity for Hg2+ and H+ ion in phosphate buffer (10 % DMSO). • Probe 7 displayed "turn – On - Off" emission in acidic and alkaline medium • Probe 7 exhibited sensitivity to visualize lysosomes and Hg2+ ion in live cells. • Probe 7 on test paper strips, showed naked-eye sensitive green color with Hg2+. A 1,5–bis(1,4-piperazinyl–naphthalimide– N –ethylmorpholine) pyridine based flexible fluorescence probe 7 is designed, synthesized, and its photophysical behavior has been examined in different media. The photophysical behavior of probe 7 in phosphate (PBS) buffer (10 % DMSO) showed pH sensitivity and selectivity for Hg2+ ion in solution and live cell with a change in naked-eye sensitive visible color. In acidic medium (pH ≤ 6) probe 7 showed enhanced (∼21 fold) "turn–On" emission, while at pH ≥ 7.4 probe 7 remained in the "turn–Off" state. The observed fluorescence "turn–On" response is attributed to inhibition in photoinduced electron transfer (PET) process. Jobs plot analysis revealed a 1:2 stoichiometry for an interaction between probe 7 and Hg2+ ion with good limit of detect (LOD) 5.78 × 10−8 M (57 nM). The reversibility in complexation and the mode of interaction were confirmed by EDTA and through NMR and HRMS spectroscopic data. MTT assay and cell imaging studies showed biocompatibility of the probe 7 to detect lysosomes and Hg2+ ion in A549 cells. For analytical application paper strip test was performed to detect Hg2+ ion with naked-eye sensitive visible color change. [ABSTRACT FROM AUTHOR]

[Display omitted] • A highly selective and sensitive chemosensor (L) for detection of Hg2+ ion in semi-aqueous medium. • The chemosensor can detect Hg2+ ions as low as 11.8 nM by spectrofluorometric by turn-off mechanism. • The practical utility of probe L was studied on the test strip, real water analysis and live cell imagaing. We have developed a new chromogenic and fluorogenic chemosensor (L) based on benzothiazole conjugated with quinolinyl acrylate for the detection of Hg2+ ions with excellent selectivity and sensitivity. In the presence of Hg2+, the fluorescence of L was quenched from light blue to colorless. The L could work in the wide pH range of 5.0–8.0 without considerable interference from other tested ions. UV–Visible and fluorometric investigations revealed that the limit of detection (LOD) for Hg2+ was 1.0 μM (202 ppb) and 11.8 nM (2.38 ppb), respectively. Further, the applicability of probe L in the determination of Hg2+ in various water samples and biological samples were tested. Human Bone Osteosarcoma cell lines (HOS) were utilized for this study and satisfying results were obtained. These cell line results also further support the 'on-off' properties of probe L. Based on the colorimetric and fluorescent results we have designed a Boolean logic gate for futuristic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Schiff base molecule (L) having pyrene and coumarin moieties was synthesized. • L is highly selective colorimetric and fluorometric probe for Al(III), Cr(III) and Fe(III) with very low detection limit. • Fluorescence response is an "OFF-ON" mechanism through inhibition of PET and operation CHEF processes. • Cell imaging and cytotoxicity studies performed using MDA-MB-231 and HDF cells indicate that L is biologically safe. A Schiff base (L) containing coumarin and pyrene moieties was synthesized and characterized. It showed excellent selective recognition of M(III) ions (M = Al, Cr and Fe) in presence of monovalent, divalent and other trivalent metal ions. Sensor L itself is non-fluorescent upon excitation with 353 nm light (λ ex = 353) but a very large enhancement in fluorescence intensity was observed during the addition of these three trivalent metal ions into a CH 3 OH/aqueous HEPES buffer (5 mM, pH = 7.4, 6:4, v/v) solution of L. This prominent "OFF-ON" fluorescence switching can be observed with naked eye, in which "OFF" is due to operation of PET process in free L but PET is inhibited upon complexation thereby allowing CHEF (chelation enhanced fluorescence) process to operate. Detection limits of Al3+, Cr3+ and Fe3+ using L have been found to be 0.79 nM, 1.15 μM, and 1.28 μM respectively in the pH range of 6‒10. Additionally, "OFF-ON" fluorescence can be reversed by sequestering M(III) ions using [EDTA]4– solutions. Analysis of mass spectra and Job's plot revealed a binding ratio of 1:1 for all three metal ions with L. The imine nitrogen and carbonyl oxygen atoms of L are involved in binding with Al3+, Cr3+ and Fe3+ ions, as revealed by NMR titration and IR spectroscopic analysis. Results of quantum yield (Φ), time resolved photoluminescence (TRPL) and computational studies (DFT/TDDFT) studies were also reported. Fluorescence intensity of these M(III) bound L complexes is quenched by fluoride ions. From cytotoxicity analysis, 7.5 μM of probe L was selected to analyze its fluorescence attributes in cellular imaging. Using human breast cancer cell line (MDA-MB-231) and primary human dermal fibroblasts (HDF), the potentiality of the probe L was confirmed through fluorescence cell imaging experiments. [ABSTRACT FROM AUTHOR]

• Hydrazide based fluorescence probe for detection of Al3+ ions. • Therotical calculations (DFT) were carried out for probe (SCH) and Al3+-SCH. • Life time decay were carried out. • SCH and Al3+-SCH used for cellular imaging sensor in MCF-7 cells Development of highly specific and susceptible sensors for aluminium (Al3+ ions) determination in water medium is still a remarkable task. Herein, a fluorescence probe (SCH) is derived from the condensation of salicyaldehyde and carbohydrazide in 2:1 M ratio and promising chemical sensing of Al3+ ions is investigated. Examinations of the emission features of SCH in CH 3 OH:H 2 O (1:2, v/v) solution showed excellent turn on behaviour of Al3+ ions, which is due to 1:1 complex formation between SCH and the Al3+ ions at ambient conditions. The lowest limit of detection was estimated by emission titration experiments and found to be 32 nM which is much more 1000-fold lower than that WHO suggested maximum tolerable concentration. The present probe SCH was highly specific for the detection of Al3+ ions over other potential interfering metal cations. Based on the reversible emission behaviour, an INHIBIT logic gate was assembled with EDTA and Al3+ ions as two inputs. In addition, prospective application of SCH as cellular imaging sensor of Al3+ ions in MCF-7 cells was monitored using optical fluorescence microscopic images and real water samples. [ABSTRACT FROM AUTHOR]