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A simple julolidine based chemosensor (JT) was designed and synthesized by single condensation step. JT displayed excellent selectivity and sensitivity with on-off responses towards Zn2+ and Cu2+ over other biologically relevant metal ions in aqueous media. Upon addition of Zn2+ ions, JT exhibited a significant blue shift in emission followed by turn- on enhancement while with Cu2+, the fluorescence intensity of JT was completely vanished. The 1:1 binding affinity between JT and Zn2+/Cu2+ was proposed by Job's plot analysis. The detection limit for Zn2+ and Cu2+ ions reached at 3.5 × 10−8 M and 1.46 × 10−6 M, respectively. The sensing mechanism of JT with Zn2+/Cu2+ was supported by DFT calculations. Based on photophysical studies and its reversibility environment with EDTA, molecular logic gates were fabricated. Furthermore, JT was successfully established to detect intracellular Zn2+ ions in live cells by turn-on response. A bifunctional chemosensor JT was synthesized to distinguish Zn2+ and Cu2+ ions based on emission on-off response. Unlabelled Image • New julolidine based Schiff base derivative (JT) was designed and synthesized and JT served as a selective emission on-off response towards Zn2+ and Cu2+ ions. • The sensor shows excellent sensitivity for Zn2+ and Cu2+ ions with an LOD at 3.5 × 10 -8 M and 1.46 × 10 -6 M, respectively. • The 1:1 binding model of the sensor JT with Zn2+/Cu2+ was established and reversibility of the chemosensor JT was proved by experiments with EDTA. • JT was successfully established to track intracellular Zn2+ ions in HeLa cells. [ABSTRACT FROM AUTHOR]

In this communication, we have developed an optical chemosensor 2-amino N-(6-bromo-1,3-dioxo-1H-benzo[ de ]isoquinolin-2(3H)-yl)benzamide ( NAPH ) for selective detection of Al 3+ by reacting 4-bromo-1,8-naphthalic anhydride with 2-aminobenzohydrazide. In (DMSO:H 2 O, 1:1, v/v) medium, the selective and specific nature of NAPH towards Al 3+ was observed by the quenching along with a blue-shift in the absorption of NAPH at 465 nm that resulted in the distinct colour change from light brown to colourless. The selective complexation that occurred between NAPH and Al 3+ was investigated by 1 H NMR and DFT methods. Under similar conditions, the weakly fluorescent receptor NAPH showed a distinct fluorescence enhancement at 555 nm in the presence of Al 3+ among the other tested metal ions and anions. The NAPH ·Al 3+ complex formation is reversible upon addition of strong chelating agent EDTA. The receptor NAPH can be applied to detect Al 3+ down to 2.9 μM without any interference from other tested metal ions. In addition, the receptor NAPH was successfully applied to detect Al 3+ in live HeLa cells. [ABSTRACT FROM AUTHOR]

A bisphenol based fluorescence "turn-on" chemosensor 4,4′-(propane-2,2-diyl)bis(2-((E)-(2-(benzo[d]thiazol-2-yl)hydrazineyldene)methyl)phenol) (BHMP) has been synthesized and its sensing behavior was tested towards various ionic species. The chemo-sensing behavior of BHMP has been established through absorption, fluorescence, NMR, and mass spectroscopic techniques. The probe BHMP selectively detects zinc ions over other metal ions and the resulting BHMP + Zn2+ ensemble serves as a secondary probe for the detection of pyrophosphate (PPi) anion specifically over other anions. The spectroscopic studies reveal the fluorescence enhancement of BHMP in association with Zn2+ ions was quenched in the presence of pyrophosphate (PPi) anions. A probable mechanism of this selective sensing behavior was described on the basis of "OFF-ON-OFF" strategy for detection of both cations and anions. Moreover, the biological applicability of the chemosensor BHMP was examined via cell imaging studies. A bisphenol based fluorescence "turn-on" chemosensor (BHMP) has been synthesized and its sensing behavior was tested towards various ionic species. The probe BHMP selectively detects zinc ions over other metal ions and the resulting Zn2+-BHMP ensemble serves as a secondary probe for the detection of PPi anion. The biological applicability of the chemosensor BHMP was examined via cell imaging studies. Unlabelled Image • The probe BHMP selectively detects zinc ions and the resulting Zn2+- BHMP ensemble is applied for the detection of PPi ions. • The probe detects Zn2+ and PPi ions with low detection limit of 0.28 and 0.87 nM respectively. • The probe was successfully applied to detect Zn2+ and PPi ions in live cells. [ABSTRACT FROM AUTHOR]

Sensing heavy metal ions particularly for the most toxic Hg2+ is a long-term pursuit for chemists because of its obvious and extreme harmfulness to both the environment and human health. Herein, a novel 'turn-on' perylenebisimide-thiourea fluorescent probe PBI-BTB is achieved for rapid detection of Hg2+ in a DMSO/H 2 O (5/1, v /v) solution through a typical Hg2+-promoting desulfurization reaction, which has been investigated through Job's plot titration, FT-IR, 1H NMR and HRMS analysis. A remarkable fluorescence emission enhancement at 540 and 580 nm is observed in the presence of Hg2+, which is visible to the naked eye with high selectivity and sensitivity. Moreover, probe PBI-BTB combined strong anti-interference recognition with short response time (< 1 min). The rapid fluorescence response with low limit of detection (0.35 μM) in a wide pH range of 3.0–11.0 makes PBI-BTB a promising candidate for detection of Hg2+ without any buffer system. Furthermore, the practicability of probe PBI-BTB upon the Hg2+ recognition in human liver cancer cells (HepG-2) has been studied through fluorescent live cell imaging which reveals the probe's low toxicity to organism as well as the favorable cell permeability of PBI-BTB for detecting Hg2+ in biological systems. Unlabelled Image • A novel fluorescent "turn-on" chemosensor for Hg2+ is developed based on perylenebisimide and thiourea. • The probe exhibited high selectivity and low detection limit for Hg2+ in a wide range of pH without any buffer system. • The probe was suitable for imaging Hg2+ ions in living cells. [ABSTRACT FROM AUTHOR]

An effective morpholine-type naphthalimide chemsensor, N- p -chlorophenyl-4-(2-aminoethyl)morpholine-1,8-naphthalimide (CMN) has been developed as a lysosome-targeted fluorometric sensor for trivalent metal ions (Fe3+, Al3+ and Cr3+). Upon the addition of Fe3+, Al3+ or Cr3+ ions, the probe CMN showed an evident naked-eye color changes which pale yellow solution of CMN turned deepened and it displayed turn-on fluorescence response in methanol. CMN showed a significant selective and sensitive toward Fe3+, Al3+ or Cr3+ ions, while there was no obvious behavior to other monovalent or divalent metal ions from the UV–vis and fluorescence spectrum. Based on the Job's plot analyses the 1:1 coordination mode of CMN with Fe3+, Al3+ or Cr3+ was proposed. The limit of detection (LOD) observed were 0.65, 0.69 and 0.68 μM for Fe3+, Al3+ and Cr3+ ions, respectively. The N-atom of morpholine directly involved in complex formation, CMN emitted fluorescence through inhibition of photoinduced electron transfer (PET). This probe exhibited excellent imaging ability for Fe3+, Al3+and Cr3+ ions in living cells with low cytotoxicity. Significantly, the cellular confocal microscopic research indicated that the lysosome-targeted group of morpholine moiety was introduced which realized the capability of imaging lysosomal trivalent metal ions in living cells for the first time. Unlabelled Image • A "turn–on" chemosensor for trivalent cations was developed. • The probe showed naked-eye color changes for trivalent cations detection. • The logic gate at molecular level was anticipated. • The probe was suitable for imaging lysosomal trivalent cations in living cells. [ABSTRACT FROM AUTHOR]