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[Display omitted] • Hydrazone based dual mode fluorescence sensor for Zn2+ ("turn-on") and Hg2+ ("turn off"). • Probe C1 selectively sense Zn2+and Hg2+ ions with their lowest detection limits 0.042 μM and 0.081 μM respectively. • The designed probe C1 was studied latent fingerprint analysis in various surfaces. • Live cell imaging studies was performed for probe C1 in presence and absence of Zn2+, Hg2+ ions. A facile Schiff base probe C1 has been developed and evaluated using 1H, 13C NMR, and mass spectroscopy. Fluorescence investigations were conducted to determine probe-sensing behavior. Probe C1 demonstrated sensitive, and selective recognition of Zn2+ and Hg2+ ions by using two distinct processes (i.e., chelation enhanced fluorescence effect and fluorescence quenching) over other cations in ACN-H 2 O (8:2, v/v). The Zn2+ and Hg2+ detection limits of 0.042 and 0.081 μM are achieved with the probe C1. C1 has a binding constant of 3.33 × 103 M−1 for Zn2+ and an emission quenching constant of 1.22 × 104 M−1 for Hg2+. A Jobs plot was used to determine the binding stoichiometry of C1 and Zn2+/Hg2+ ions ratio is 1:1. By using Zn2+/Hg2+ and EDTA additions alternately, the probe's reusability was investigated. Moreover, the probe was found to be highly cytocompatibility using an MTT assay in a mouse fibroblast cell line (NIH3T3). Further, the probe was found to visualize Zn2+ and Hg2+ ions inside the cells, indicating the potential application of the probe as an intracellular probe to detect Zn2+ and Hg2+ ions. The probe shows very good solid-state emission behavior, this motivates us to develop latent fingerprint detection and anticounterfeiting applications. [ABSTRACT FROM AUTHOR]

Mercury (Hg) is one of the most widespread pollutants that pose serious threats to public health and the environment. People are inevitably exposed to Hg via different routes, such as respiration, dermal contact, drinking or diet. Hg poisoning could cause gingivitis, inflammation, vomiting and diarrhea, respiratory distress or even death. Especially during the developmental stage, there is considerable harm to the brain development of young children, causing serious symptoms such as intellectual disability and motor impairments, and delayed neural development. Therefore, it's of great significance to develop a specific, quick, practical and labor-saving assay for monitoring Hg2+. Herein, a mitochondria-targeted dual (excitation 700 nm and emission 728 nm) near-infrared (NIR) fluorescent probe JZ-1 was synthesized to detect Hg2+, which is a turn-on fluorescent probe designed based on the rhodamine fluorophore thiolactone, with advantages of swift response, great selectivity, and robust anti-interference capability. Cell fluorescence imaging results showed that JZ-1 could selectively target mitochondria in HeLa cells and monitor exogenous Hg2+. More importantly, JZ-1 has been successfully used to monitor gastrointestinal damage of acute mercury poisoning in a drug-induced mouse model, which provided a great method for sensing Hg species in living subjects, as well as for prenatal diagnosis. [Display omitted] • An activated probe JZ-1 for fluorescent detecion of Hg2+ was devised. • JZ-1 has dual NIR excitation and emission analysis wavelengths (both > 700 nm). • JZ-1 has a rapid response time and outstanding detection limit. • It was successfully used to in a drug-induced mouse of acute mercury poisoning. [ABSTRACT FROM AUTHOR]

• CM exhibit "Turn-On" blue fluorescence response for Ca2+ in solution, which is free from interference of co-existing cations. • "Tyndall Effect" can be observed during chelation, blue emissive nanowires induced by aggregation were investigated. • The molecular docking result reveals CM can bind with receptor 1A of melatonin via hydrogen bond. • CM and its Ca2+ complex shows good cell permeability and low cytotoxicity, their localization in organelle were studied. Due to a physiological significant role of calcium ion, it is essential to develop ways of detecting and monitor the level of Ca2+ ions in living cell. Herein, we rationally designed and synthesized a functional blue fluorescent compound CM based on amide condensation of coumarin and melatonin. Interestingly, it could exhibit an "On-OFF" fluorescence response for Ca2+ in an aqueous environment with 80-fold enhancement in bright blue emission, which is also free from interference of other co-existing cations of high concentration. A detection limit of 0.28 ppm was obtained, and the binding ratio of CM and Ca2+ is further investigated by Job's plot. After coordination of CM with calcium ion, a significant "Tyndall Effect" can be observed, and blue emissive nanowires induced by aggregation of complex of CM and Ca2+ were further investigated by Dynamic Light Scattering, analysis of Zeta potential, and confocal imaging. The molecular docking of CM with melatonin receptor 1A is also conducted. MTT assay reveals that CM ligand and the corresponding Ca2+ complex are non-cytotoxic. Moreover, CM shows good membrane permeability, and the relative cellular uptake mechanism is mainly dominated by an energy-dependent process. CM and its complex of Ca2+ can be further used as intracellular luminescent imaging probes and their localization in cell organelles is also revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe YX is a near-infrared fluorescent probe. • The probe YX can complete continuous detection Zn2+ and PPi. • The probe YX has a good application prospect in biology. • The probe can detect Zn2+ and PPi in actual samples. As the second most abundant transition metal element in the human body, zinc ions play an important role in the normal growth and development of the human body. We have successfully synthesized a near-infrared fluorescent probe with FRET effect for the detection of Zn2+. Probe DR6G has good selectivity and anti-interference ability for Zn2+. When Zn2+ is added to the probe DR6G solution, it responds completely within seconds, releasing red fluorescence with a detection limit of 2.02 × 10−8 M. As the main product of ATP hydrolysis, PPi is indispensable in various metabolic activities in cells and the human body. Due to the strong binding ability of Zn2+ and PPi, it is easy to form ZnPPi precipitation, so we added PPi to the solution to complete the Zn2+ detection, and realized the continuous detection of PPi, and the detection limit was 2.06 × 10−8 M. Since Zn2+ and PPi play an important role in vivo, it is of great practical significance to design and synthesize a fluorescent probe that can continuously detect Zn2+ and PPi. Biological experiments have shown that the probe DR6G has low cytotoxicity and can complete the detection of exogenous Zn2+ and PPi in cells and living mice in vitro. Bacterial experiments have shown that the DR6G probe also has certain research value in the field of environmental monitoring and microbiology. Due to the constant variation of the fluorescence signals of Zn2+ and PPi during detection, we designed the logic gate program. In practical applications, the probe DR6G can quantitatively detect Zn2+ in zinc-containing oral liquids and qualitatively detect PPi in toothpaste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Facile synthesis of fluorescent CDs from Schyzium cumini leaves by hydrothermal process. • CDs displayed excitation dependent emission with quantum yield of 15.9 %. • CDs have been used as sensing probe for the detection of Fe3+. • Low limits of detection and >85 % recovery in real water samples. • The synthesized CDs exhibits good biocompatibility and low cytotoxicity. In this study, carbon dots (CDs) derived from Syzygium cumini leaves were synthesized through a hydrothermal process and employed as a sensing probe for the highly sensitive and selective detection of Fe3+. The synthesized CDs underwent comprehensive analysis to discern their functional groups, composition, morphology, nature, and size. The CDs exhibited excitation-dependent emission fluorescence with a quantum yield of 15.9 %. Notably, Fe3+ induced a substantial quenching effect on the fluorescence intensity of the CDs compared to other metal ions. The developed fluorescent probe facilitated the selective detection of Fe3+ within a linear range of 0–300 µM, exhibiting a low detection limit (LOD) of 0.13 µM. Moreover, the applicability of the fluorescent probe was validated in real water samples, with the recovery and Relative Standard Deviation (RSD) values serving as indicators of specificity and selectivity. Additionally, the CDs were assessed for cell imaging in both normal human and cancer cells. The findings indicate that the produced CDs exhibit minimal cytotoxicity and outstanding biocompatibility, underscoring their potential for bioimaging applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A naphthalimide-based fluorescent probe for relay recognition of Cu2+ and S2− has been designed and synthesized. • The sensor has lower detection limit for Cu2+ and S2−. • Fluorescence behavior in the presence of Cu2+ and S2− could be manufactured to IMPLICATION type logic gate. • Intracellular fluorescence imaging in living cells were developed. A fluorescent chemosensor based on naphthalimide derivative (HL) was prepared and characterized. HL exhibited strong fluorescence emission at 528 nm, which was attributed to naphthalimide moiety, while the addition of Cu2+ almost completely quenched the fluorescence emission. However, with the addition of S2−, the fluorescence at 528 nm reoccurred remarkably. The detection limits for Cu2+ and S2− were measured to be 1.72 × 10−7 M and 2.66 × 10−7 M, respectively. As determined, the fluorescence behavior of HL in the presence of Cu2+ and S2− could be manufactured to IMPLICATION type logic gate. Moreover, confocal fluorescence imaging in HepG2 cells indicated that the HL could act as a useful fluorescent probe for intracellular Cu2+ and S2− detection with negligible cytotoxicity. [ABSTRACT FROM AUTHOR]

A new hemicyanine-based near-infrared "off-on" recognition Cu2+ fluorescent probe NRh-NP was designed and successfully synthesized. The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. NRh-NP has high sensitivity, selectivity and a low limit of detection (33 nM as fluorescence sensor and 35 nM as UV sensor) to Cu2+. According to Job's plot and ESI-HRMS, the coordination ratio of NRh-NP to Cu2+ was 1:1. DFT theoretical calculations proved that the sensor mechanism was photo-induced electron transfer (PET). More importantly, NRh-NP has excellent membrane permeability and low cytotoxicity, which could be used not only for the detection of Cu2+ in human breast cancer cells (MCF-7), but also for imaging Cu2+ in living mice. [Display omitted] • The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. • The responses of NRh-NP toward Cu2+ were fully proved by Job's plot, ESI-HRMS and DFT theoretical calculations. • NRh-NP has high sensitivity and selectivity with detection limit as low as 33 nM. • NRh-NP can be used for Cu2+ imaging in living cells and in vivo. [ABSTRACT FROM AUTHOR]

• Synthesized a unique naphthalimide-rhodamine based chemosensor (NR-HG) for the selective detection of Hg2+ ion. • NR-HG shows an impressive LOD 491 nM and exhibits reversibility. • Synthesized Probe works through PET, CHEF, and FRET leading to the chelation-induced ring opening. • TD-DFT calculation supported the origin of the fluorescence emission maxima. • NR-HG is stable in biological pH and can efficiently image Hg2+ in SiHa cells under the fluorescence microscope. In this work, we are presenting the design and synthesis of an innovative fluorescent chemosensor: NR-HG, established on a naphthalimide-based rhodamine platform for Hg2+ ion sensing. The probe operates via PET, CHEF, and FRET mechanisms. The fluorescent chemosensor shows an immense selectivity and sensitivity towards Hg2+ ion via the enhancement of ring-opening rhodamine spiro-cyclic structure, with a detection limit (LOD) of 491 nM. The DFT analysis strongly validates the experimental observations. The probe senses the Hg2+ ion reversibly upon the addition of potassium iodide (KI). From the analysis of Job's plot, it can be conclusively confirmed that the NR-HG-Hg2+ complex demonstrates a 1:1 stoichiometric ratio. We also conducted an MTT assay and cell imaging experiment to assess both the compatibility of the probe with living cells and its effectiveness in real-life imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A colorimetric and fluorometric dual-signals probe Rb-HMD based on rhodamine B and tetrapeptide was firstly synthesized. • Rb-HMD exhibited a fluorescence "turn-on" response and colorimetric analysis to trivalent ions (Fe3+, Al3+ and Cr3+). • Rb-HMD showed low detection limits for sensing of Fe3+ (16.4 nM), Al3+ (0.12 μM) and Cr3+ (0.24 μM). • Rb-HMD was successfully applied for trivalent ions (Fe3+, Al3+ and Cr3+) imaging in living cells. • Smartphone-assisted probe Rb-HMD was used to realize the semi-quantitative detection of Fe3+ ions. In this study, a new dual-signals probe Rb-HMD with colorimetric and fluorescent was designed and synthesized by conjugating tripeptide backbone (His-Met-Asp-NH 2) with a rhodamine B derivative using solid phase peptide synthesis (SPPS) technology. Rb-HMD exhibited highly selective recognition of trivalent ions (Fe3+, Al3+ and Cr3+) by fluorescence enhancement and colorimetric observation in the presence of other competing metal ions. Notably, the limit of detections (LODs) for Fe3+, Al3+, and Cr3+ were 16.4 nM, 0.12 μM and 0.24 μM, respectively, indicating that Rb-HMD has good application prospects for high sensitive detection of Fe3+, Al3+ and Cr3+ in real samples and biological systems. Additionally, cytotoxicity and cells imaging demonstrated that Rb-HMD has very low toxicity in living cells even at concentrations up to 80.0 μM, and was successfully applied to detect Fe3+, Al3+ and Cr3+ in living cells. Moreover, the gradient change of color of Rb-HMD was captured by smartphone under UV light at 365 nm, and then content analysis was carried out by color recognition APP , which makes it possible to detect Fe3+ in rapid and accurate semi-quantitative way without other large valuable instruments. [ABSTRACT FROM AUTHOR]

• A mitochondria-targeted ratiometric fluorescent probe for cyanide was developed. • Mito-CP can detect endogenous cyanide in plant tissues and rat PC12 cells. • Mito-CP can recognize cyanide with dual-channel mode fluorescence imaging. • Mito-CP could detect cyanide in real water samples with quantitative detection. Various fluorescence probes for cyanide anions in water solution have been reported, but the investigation for endogenous cyanide recognition in plant tissues and mammalian cells is still limited. Here, a mitochondria-targeted cyanide fluorescent probe Mito-CP with colorimetric and ratiometric response was developed. The detection for cyanide was performed via the nucleophilic addition of cyanide to carbon-carbon double bond between coumarin moiety and pyridine moiety of the probe, which resulted in a color change from red to colorless and fluorescence change from red to blue. The probe showed high sensitivity (0.17 nM) and selectivity for cyanide over other common anion species and biothiols and could detect cyanide in real water samples with quantitative detection. Probe Mito-CP was successfully applied to detect endogenous cyanide in cassava root plant tissues. In addition, colocalization experiment showed that the probe has the property of targeting mitochondria with overlap coefficient being 0.93. A549 and HeLa living cells imaging experiment demonstrated the practical value of the probe in tracing CN− in biological systems. The probe also can detect endogenous cyanide change in mitochondria of rat pheochromocytoma (PC12) cells. [ABSTRACT FROM AUTHOR]

Abstract A novel fluorescent probe, phenolphthalein‑dialdehyde‑(2‑pyridyl) hydrazone (L), for sequentially detecting Al3+ and F− in almost 100% aqueous medium was successfully designed and synthesized. The probe offers two binding pockets for Al3+ to form a 1: 2 ligand/metal complex, leading to a significant fluorescence enhancement at 465 nm. Further, the in-situ formed L-Al complex acts as a secondary fluorescent chemosensor for F− by quenching the fluorescence of the complex with high selectivity. The detection limit for Al3+ and F− sensing is 2.28 nM and 0.13 μM, respectively, which are far below the World Health Organization (WHO) acceptable limits (7.41 μM for Al3+ ion and 79 μM for F−) in drinking water. The probe L was successfully applied to the detection of Al3+ and F− in cells using fluorescence microscopy. Graphical Abstract The new fluorescent probe L can be used for selective detection of Al3+ and F− in almost 100% aqueous medium and live cells. Unlabelled Image Highlights • A new fluorescent probe L was synthesized and characterized • L can be used for selective detection of Al3+ and F−. • L exhibits a fluorescence response in almost 100% aqueous medium and live cells. • The detection limit for Al3+ was as low as nano-molar level. • L was employed for imaging the Al3+ and F− in living biological cells. [ABSTRACT FROM AUTHOR]

Abstract Herein we pay attention to the design, synthesis and sensor activity of a novel biocompatible perylene-3,4,9,10-tetracarboxylic diimide (PDI) pH-probe in water. The synthesized compound shows selective fluorescence signalling properties as a function of pH (p K a value of 6.35 ± 0.02) which makes the probe suitable for pH determination in the physiological range. Thus prepared water soluble fluorescent system demonstrate low cytotoxicity to L929 cell lines from 330 μM to 1.3 μM and cell permeability in the lower concentration range. That findings show the high potential of the newly prepared PDI probe for monitoring of pH variations in bio-samples. Graphical abstract Image 1 Highlights • Fluorescent water-soluble perylene diimide pH probe is synthesized. • Probe is configured on the " fluorophore-spacer-receptor " model. • Probe operates via photoinduced electron transfer. • Probe shows low cytotoxicity towards L929 cell line. • Nano sized probe is cell-permeable at 0.001 mg/mL concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • The near-infrared (NIR) turn-on fluorescence probe (aza-BDP-Pro) based on aza-BODIPY derivative was prepared for detecting Au3+ ions. • Aza-BDP-Pro probe can detect Au3+ with a low detection limit in aqueous solution. • The probe showed a remarkable fluorogenic change under UV light. • Aza-BDP-Pro was acceptable applied as an intracellular Au3+-tracking agent in living human cells. A new near-infrared (NIR) fluorescent probe for the determination of Au3+ ions was synthesized by introducing boron dipyrromethene moiety as a fluorophore and attaching it with propyne groups as a Au3+-specific recognition unit. The photophysical properties revealed that the fluorescent emission of the sensor was observed in the NIR region with a wavelength of 713 nm. Furthermore, the sensor exhibited excellent sensitivity to Au3+ ions with fluorescent enhancement behavior in aqueous media and naked-eye observation through a colorimetric change from green to yellow. The detection limit of aza-BDP-Pro was found to be 0.64 µM (0.126 ppm). The probe was successfully utilized for selectively detecting Au3+ ions against other 18 interfering metal ions and tracking Au3+ ions in vivo for imaging application. [ABSTRACT FROM AUTHOR]

A potential fluorescent probe, N'-acetyl-2-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)acetohydrazide (HMC1) was designed on the basis of photoinduced electron transfer (PET) and synthesized using cheap starting materials. HMC1 was found to be highly efficient as a Cu 2+ ion quencher with a detection limit of 0.64 μM (~ 40 ppb). The binding mode of HMC1 towards Cu 2+ was evaluated by 1 H NMR, LC-MS and FT-IR techniques. In addition, cellular imaging studies further exhibited that HMC1 could be used an intracellular turn-off fluorescent chemosensor for Cu 2+ in living cells. [ABSTRACT FROM AUTHOR]

The development of sensitive chromogenic chemosensors for sensing Cu 2+ has been receiving much attention in recent years because of their potential application in clinical biochemistry and the environment studies. Numerous chemosensors have been developed for selective recognition of different species on the basis of host–guest interactions such as hydrogen-bonding, electrostatic force, metal–ligand coordination, hydrophobic and van der Waals force of interactions. The simple and rapid sensing of Cu 2+ ions in biological and environmental systems is desirable and the development of selective and sensitive imaging tools capable of monitoring Cu 2+ ions rapidly has attracted considerable attention. Fluorescent chemosensors have served as useful tool for detecting metal ions owing to their intrinsic sensitivity, selectivity and capacity for rapid, real-time monitoring. Small-molecule fluorescent probes can make use of selective, bio-orthogonal chemistries to report on specific analytes in cells and in more complex biological specimens. This review presents a survey of strategies for using small-molecule fluorescent probes to detect Cu 2+ ions which cover UV to NIR regions such as anthracene, pyrene, quinoline, quinazoline, dansyl, naphthalimide, rhodamine, fluorescein, BODIPY and cyanine dyes. [ABSTRACT FROM AUTHOR]

A coumarin-based sensor C1 , namely 3-acetoacetylcoumarin was designed, synthesized and applied for hydrazine detection. Hydrazinolysis of the chemosensor gives a fluorescent coumarin-pyrazole product C1 − N 2 H 4 [3-(3-methyl-1H-pyrazol-5-yl)coumarin], and thus resulting in a prominent fluorescence off-on response toward hydrazine under physiological conditions. The probe is highly selective toward hydrazine over cations, anions and other biologically/environmentally abundant analytes. The detection limit of the probe is 3.2 ppb. The sensing mechanism was supported by 1 H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated. [ABSTRACT FROM AUTHOR]

A fluorescence probe has been designed and synthesized, and applied with a combined theoretical and experimental study. Research suggests that the probe can be used to sense Zn 2 + and Hg 2 + through selective turn-on fluorescence responses in the aqueous HEPES buffer (0.05M, pH = 7.4). The limit of detection (LOD) were determined as 1.46 × 10 − 7 M (Zn 2 + ) and 2.50 × 10 − 7 M (Hg 2 + ). Moreover, based on DFT, the geometry optimizations of probe 1, [1-Hg 2 + ] complex and [1-Zn 2 + ] complex were carried out using the Gaussian 09 program, in which the B3LYP function was used. The electronic properties of free probe 1 and the metal complexes were studied based on the Natural Bond Orbital (NBO) analyses. The probe 1 has also been successfully applied to detection of Zn 2 + and Hg 2 + in living cells. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe XDS based on 4-methylumbelliferone and 2-picolylamine platforms has been designed and synthesized, which behaves fast relay recognition of Fe 3+ and PO 4 3− via a fluorescence “on−off−on” response signal. Probe XDS exhibited very high sensitivity and unique selectivity for Fe 3+ over other common metal ions, and the detection limit of was 3.2 × 10 −7 M. Moreover, the addition of the PO 4 3− ions could cause the recovery of fluorescence. This relay recognition feature of probe XDS has potential applications in the determination of trace amount of Fe 3+ and PO 4 3− in environmental systems. Interestingly, fluorescence imaging experiments demonstrated that the probe XDS can also be used to monitoring the intracellular Fe 3+ in RAMOS cells. [ABSTRACT FROM AUTHOR]

A schiff-base dual emission ratiometric fluorescent chemosensor which includes coumarin dye and 5-aminoisophthalic acid methyl ester has been designed and synthesized. The chemosensor CA high selectively detects Hg 2+ ions in the presence of other biologically important and environmentally relevant metal ions at physiological pH. The double bond of schiff-base was broken accompanied by fluorescence enhancement when the chemosensor interacts with Hg 2+ ions, and the coumarin aldehyde and 5-aminoisophthalic acid methyl ester shows strong ratiometric fluorescent emission respectively. And the chemosensor could be applied in cellular imaging at nano molarity by dual fluorescent emission. [ABSTRACT FROM AUTHOR]

At present, few genetically encoded fluorescent probes are currently available for the analysis of toxic heavy metal ions, and most have poor performance that cannot meet the requirements of sensitive and dynamic detection in living cells. In this study, we designed a single fluorescent protein-based probe sfGFP-MerBD, which can specifically response to Hg2+ with high binding affinity and wide dynamic range. More importantly, the developing probe can timely and reversibly monitor changes of Hg2+ concentration in living mammalian cells. The excellent performance of this probe is largely due to the recognition element of the probe, MerBD, which adopts an unusual planar trigonometric coordination configuration with Hg2+, and the coordination can cause enough conformational change to influence the fluorescence of skeleton protein sfGFP coupled with it. The small peptide MerBD was delicately designed based on the three-dimensional structure of metalloprotein MerR. This novel design strategy solves the challenging problems that there are few natural functional proteins in the process of constructing fluorescent probes for toxic metal ions and some functional proteins cannot be directly used as recognition elements. Based on the new strategy, more genetically encoded fluorescent probes of toxic heavy metal ions can be efficiently constructed and applied in the future. [Display omitted] • Genetically encoded probes are ideal tools in living cellular imaging. • Few genetically encoded probes related for toxic heavy metal are currently available. • Novel strategy is adopted in constructing the probe sfGFP-MerBD for sensing Hg2+. • The probe maintains the unusual planar trigonometric coordination with Hg2+. • The probe responses to Hg2+ with high binding affinity and wide dynamic range. [ABSTRACT FROM AUTHOR]

A rhodamine hydrazide conjugating uridine moiety (RBH-U) is firstly synthesized by screening different synthetic routes, and then developed as a fluorescence probe for selective detection of Fe3+ ions in an aqueous solution, accompanied by visual color change with naked eyes. Upon the addition of Fe3+ in a 1:1 stoichiometry, a 9-fold enhancement in the fluorescence intensity of the RBH-U was observed with an emission wavelength of 580 nm. In the presence of other metal ions, the "turn-on" fluorescent probe with pH-independent (value 5.0 to 8.0) is remarkably specific for Fe3+ with a detection limit as low as 0.34 μM. Further, the enhanced fluorescence intensity of RBH-U- Fe3+ can be quenched as a switch-off sensor to assist in the recognition of Cu2+ ions. Additionally, the colocalization assay demonstrated that RBH-U containing uridine residue can be used as a novel mitochondria-targeted fluorescent probe with rapid reaction time. Cytotoxicity and cell imaging of RBH-U probe in live NIH-3T3 cells suggest that it can be a potential candidate for clinical diagnosis and Fe3+ tracking toll for the biological system due to its biocompatibility and nontoxicity in NIH-3T3 cells even up to 100 μM. [Display omitted] • A novel mitochondria-targeted fluorescent probe (RBH-U) at 580 nm of emission. • Upon the addition of Fe3+ in a 1:1 stoichiometry, a 9-fold fluorescence intensity enhancement is occurred. • The efficient target of mitochondria, and selective recognition of Fe3+ in vivo and Cu2+ in vitro. [ABSTRACT FROM AUTHOR]

A novel AIE active fluorescence chemosensor 1 was synthesized with 2-benzothiazoleacetonitrile and 4-(diphenylamino)-benzaldehyde in 73% yield. 1 exhibited prominent selective and sensitive detection to cyanide with significant turn-off fluorescent response in almost pure aqueous media. Moreover, 1 achieved a low detection limited of 0.22 μm (9.44 ppm) which is lower than the maximum level of cyanide in the drinking water (1.9 μm) that the World Health Organization (WHO) permits. The fluorescent response to CN − was attributed to the nucleophilic addition of CN − to the vinyl group of 1 resulting in breaking of the conjugated, which was supported by Job’s plot and 1 H NMR titration. The biological applications of 1 were also evaluated and found that 1 exhibited low cytotoxicity and membrane permeability. Furthermore, 1 -based test strips could also detect CN − conveniently. [ABSTRACT FROM AUTHOR]

A new on-off fluorescent probe 1 for Cu 2+ based on Schiff base compound was designed and synthesized by one-step reaction. The single probe 1 exhibited strong green fluorescence emission. A fluorescence quenching effect and faint color change were observed as soon as the Cu 2+ was added to the probe system in H 2 O/EtOH (v/v = 8:2, HEPES buffer, 0.05 M, pH = 7.4) solution. Other common metal cations did not cause the changes in the fluorescence and color of the probe 1. The optical properties were studied by the fluorescence emission and UV–Vis spectra. Meanwhile, the geometry optimizations of probe 1 and the [1-Cu 2+ ] coordination complexes were also carried out by DFT using the Gaussian 09 program, in which the B3LYP function was used. Based on experimental measurement and theoretical analysis, we can know that the combination ratio of the probe and Cu 2+ is 2:1 and the limit of detection (LOD) is as low as 5.3 × 10 −9 M Besides, the probe 1 was also used to analyze the Cu 2+ in living cells. [ABSTRACT FROM AUTHOR]

Developing simple probes to sense Al 3+ in vivo and in vitro in real time is highly desirable as Al 3+ imbalance has been linked to a variety of diseases in human being. Here, we introduce a new, highly selective and sensitive Schiff base chemosensor, H 2 bpet , based on benzophenone that can detect Al 3+ in a 0.01% ethanol in 50 mM HEPES buffer medium by fluorimetric sensing. The structure of the probe, H 2 bpet involves existence of keto−–enol tautomerism. Single crystal X-ray diffraction study reveals prevalence of keto form of H 2 bpet in the solid state. The binding properties of H 2 bpet with Al 3+ was thoroughly investigated by fluorescence spectroscopy and ESI–MS analyses. The binding of Al 3+ to the probe H 2 bpet , induces distinct 1 H and 13 C NMR shifts in favour of H 2 bpet (keto form):Al 3+ aggregate. The sensing mechanism of H 2 bpet toward Al 3+ and composition of H 2 bpet:Al 3+ aggregate was proposed and established by DFT/TDDFT calculations. Its application in fluorescent imaging in HepG2 cells was also tested. This report demonstrates an advancement in detection of Al 3+ with the introduction of a new benzophenone containing Schiff base chemosensor. [ABSTRACT FROM AUTHOR]

Thymol (2-isopropyl-5-methylphenol), the major constituent of ajwain, is a naturally occurring monoterpene phenol having antioxidant, anti-inflammatory and antimicrobial activities. Herein, we report 4-hydroxy-5-isopropyl-2 methylisophthalaldehyde (DFT) derived from thymol and its derivatives as selective fluorescent chemosensors for Mg 2+ in aqueous medium. These probes can selectively detect Mg 2+ ion and efficiently images intracellular free Mg 2+ in living RAW 264.7 and HeLa cells under fluorescence microscope without any interference from common metal ions. Density Function Theory studies strongly support the experimental facts. [ABSTRACT FROM AUTHOR]

A novel and efficient quinoline-based fluorescent chemosensor (QLSA) for zinc(II) ion (Zn 2+ ) detection was reported. This sensor was facilely synthesized via a simple linker NH 2 –NH 2 connected quinoline-2-carboxylic acid and salicylaldehyde. This non-fluorescent quinoline derivative can detect Zn 2+ with high sensitivity and favorable specificity and lead to significant fluorescence OFF–ON switching. The detection limit for Zn 2+ was found to be 2.1 × 10 −8 M. The mechanism of the interaction between the sensor and Zn 2+ has been investigated in detail through NMR and HRMS analysis. The sensor exhibited low cytotoxicity and larger Stokes shifts (171 nm) which are important and desired features for a fluorophore in live-cell imaging. Moreover, further application of the sensor in fluorescence imaging was studied in Hela cell by confocal fluorescence microscopy, suggesting that the sensor was proved to be a useful tool for tracking Zn 2+ levels in vivo . [ABSTRACT FROM AUTHOR]

A novel pyridyl functionalized rhodamine dye with large Stokes shift and stable fluorescence in water was facilely prepared and utilized for a Hg2+-selective probe. [Display omitted] • A Rhodamine derivative PR has been prepared with Stokes shift of 81 nm. • Probe PRHg is synthesized, presenting high selectivity and sensitivity (LOD: 8.5 nM) to Hg2+. • PRHg exhibits great potential for tracing Hg2+ in living cells. Rhodamines gain sustained attention owing to their great potential for probe design applications. Herein, the facile preparation of a new pyridyl functionalized rhodamine dye PR is reported, which has stable fluorescence signal in water with maximum emission peak at 594 nm and Stokes shift of 81 nm. Based on dye PR , a new fluorescent probe PRHg has been developed by modifying the spirolactone of PR with hydrazine hydrate so as to produce spirolactam recognizing group for sensing of Hg2+. PRHg exhibits high selectivity and sensitivity towards Hg2+ in water/ethanol (v/v = 4/1, pH = 7.0) by a specific Hg2+-binding promoted spirolactam ring opening and hydrolyzing process. And, the detection limit for Hg2+ is evaluated to be 8.5 nM. Besides, the probe can respond to Hg2+ within 40 min and over a wide pH range from 4.0 to 10.0. Moreover, PRHg (40 µM) performs low cytotoxicity to HeLa cells (over 91.0 % cell survival rate), which allows the probe to be employed for tracing intracellular Hg2+ by fluorescence imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new piperazine-based phenanthridine sensor probe was synthesized and characterized. • The fluorescence revealed that 5a is a superior selective sensor towards Th4+ ion in the presence of other competitive metal cations. • The kinetic study realized the detection of Th4+ ions in 15 s. • The limit of detection value is as low as 2.76 nM for Th4+ ion. • Probe 5a has been investigated for test paper strips applications as well as Th4+ ion analysis in real water samples. A benzhydrylpiperazine-based phenanthridine (5a) moiety has been developed as a ratiometric fluorescence and colorimetric probe for the detection of Th4+ ion. After the addition of Th4+ ion, probe 5a was immediately color-altered from blue to yellow fluorescence with an emission maximum at 560 nm. Probe 5a showed superior selectivity and sensitivity towards Th4+ ions over the other competitive metal ions. This sensor probe exhibited a lower detection limit (2.76 nM). Then through the 1H NMR titration experiment, it was confirmed that the benzhydrylpiperazine moiety of 5a was chelated with Th4+ ion. However, probe 5a was utilized for the detection of Th4+ ion in real water samples and monazite sand. Most importantly, the application of this sensor probe 5a for the recognition of Th4+ ion in E. coli cells had been successful. [ABSTRACT FROM AUTHOR]

In the present study, we developed a novel fluorescent chemosensor with a hybrid structure of 3-pyridinonitrile-coumarin derivatives by molecular design strategy that can effectively label intracellular lipid droplets. Interestingly, the probe ATOP-LD also exhibited polarity-sensitive properties, which may be attributable to its own strong electron-giving and electron-absorbing moieties. In addition, the probe exhibited excellent interference resistance, pH stability and low biotoxicity and had been successfully applied to cell imaging. Also, probe ATOP-LD could discriminate dead and living zebrafish or its embryos. These satisfactory properties prove that the probe is useful and possesses great potential for application. Lipid droplets (LDs) represent essential intracellular organelles that store and supply lipids, which are associated with the synthesis of many disease-related intracellular signalling molecules. Aberrant expression of lipid droplets may cause cytotoxicity, cellular dysfunction and apoptosis. Similarly, as a very critical parameter and indicator of normal cells, polarity performs a vital function in many biological processes and physiological environments. In the present study, we developed a novel fluorescent chemosensor by molecular design strategy that can effectively label intracellular lipid droplets. Interestingly, the probe ATOP-LD also exhibited polarity-sensitive properties, which may be attributable to its own strong electron-giving and electron-absorbing moieties. Iinaten addition, the probe exhibited excellent interference resistance, pH stability and low biotoxicity, and had been successfully applied to cell imaging. Also, probe ATOP-LD could discriminate dead and living zebrafish or its embryos. [Display omitted] • A novel fluorescent chemosensor by molecular design strategy was developed, which can effectively label intracellular lipid droplets. • The probe ATOP-LD also exhibited polarity-sensitive properties, which may be attributable to its own strong electron-giving and electron-absorbing moieties. • The probe exhibited excellent interference resistance, pH stability and low biotoxicity. • Probe ATOP-LD had been successfully applied to cell imaging, zebrafish and its embryos imaging. • The probe was useful to discriminate dead and living zebrafish, which is a very cleaver application. [ABSTRACT FROM AUTHOR]

Pyridoxal-2-hydrazinopyridine Schiff-base ( 1 ) was prepared by one-step synthesis from commercially available materials of pyridoxal and 2-hydrazinopyridine. Compound 1 could be applied as a fluorescent chemosensor for Zn(II) in aqueous solution at pH 7.4. After binding to Zn(II) with a molar ratio of 1:1, 1 exhibited 17-fold fluorescence enhancement. In addition, 1 showed a good selectivity toward Zn(II) over other metal ions, which can especially distinguish Zn(II) from Cd(II). A linear range of 5.0–20.0 μmol L −1 and a detection limit of 70 nmol L −1 were also achieved. Moreover, the utility of chemosensor 1 in bioimaging of Zn(II) in living cells was demonstrated, which suggested that 1 could be used as a Zn(II)-selective chemosensor in biological samples. [ABSTRACT FROM AUTHOR]

We describe the quantitative synthesis of a Schiff base derived from methionine and salicylaldehyde (SMSB) which displayed turn-on selective fluorescent chemo-sensing properties for Zn 2+ in buffered CH 3 CN/H 2 O (1:1) solution. In physiological pH (7.2 buffered) SMSB exhibited high selectivity and sensitivity toward Zn 2+ over the other selected metal ions. Upon the addition of Zn 2+ 33 folds of emission enhancement was observed in SMSB and limit of detection ( C L ) for Zn 2+ was found to be 5.0 × 10 −7 M. This binding phenomenon was studied by 1 H NMR and HR-MS analysis. Mass spectrometry analysis revealed that SMSB interacts with Zn 2+ and form a 1:1 complex, also confirmed by Job's plot. This probe was completely retrieved by adding EDTANa 2 solution, exhibited a fluorescent quenching effect by removing Zn 2+ from the sensor. SMSB was observed to have a good tolerance for fluorescence detection of Zn 2+ in pH range 6–10. Furthermore it is successfully investigated for living cells imaging using MCF-7 cells. Combine experimental results indicated SMSB to be a useful and powerful chemosensing probe for Zn 2+ in water as well as in living cells. [ABSTRACT FROM AUTHOR]

Based on spirolactam ring-opening reaction, a chromogenic and “off–on” fluorescent sensor for determination of palladium (II) was developed in this paper. The novel sensor was easily synthesized from rhodamine B hydrazide and diacetyl monoxime named RBM. The structure of the sensor has been characterized by ESI-MS and NMR. EDTA-adding experiment indicated that the binding of chemosensor RBM and Pd 2+ was chemically reversible. The fluorescence intensity and absorbance of the sensor showed a good linearity with the concentration of Pd 2+ in the range of 0–15 μM and 0–17 μM, respectively, with detection limits of 0.015 μM and 0.200 μM. Moreover, it has been successfully applied to detect Pd 2+ in palladium-containing catalyst, natural water samples and imaging of Pd 2+ in living cells with satisfying results. The study indicated that this novel sensor could be an attractive approach to detect Pd 2+ in environmental systems and biological systems. [ABSTRACT FROM AUTHOR]

Two unique pyrene derivatives are reported as Zn 2+ selective fluorescent probes, in which two pyrenes bearing imine and OH groups are connected via an ether linker or thioether linker. Upon the addition of Zn 2+ , the resulting phenolate group can induce internal charge transfer (ICT) peaks, which can cause selective turn-on fluorescence of each probe at 550 nm. Bathochromic shifts of their emissions are observed upon the binding with Zn 2+ . Each probe can successfully image exogenous Zn 2+ ions as well as free zinc ions released during apoptosis. These results using live cells suggest that these pyrene derived probes can be very effective probes in zinc biology studies. [ABSTRACT FROM AUTHOR]

N -Phenylthiosemicarbazones (R 1 –R 4 ) have been synthesized and characterized by various spectroscopic techniques. The sensors (R 1 –R 4 ) exhibited highly selective and sensitive recognition toward Cu 2+ and F − ions over other cations and anions via visual color change. Sensors showed a significant fluorescent enhancement toward Cu 2+ in aqueous medium and found a sub-nanomolar detection limit with good quantum yield. R 1 displayed high selectivity to Cu 2+ over other interference ions with 89-fold fluorescence intensity enhancement upon the addition of 2 equiv. of Cu 2+ . In addition, the turn-on fluorescent changes upon the addition of Cu 2+ , is also applied in cell imaging. [ABSTRACT FROM AUTHOR]

A new o-aminophenol-based fluorogenic chemosensor methyl 3,5-bis((E)-(2-hydroxyphenylimino)methyl)-4-hydroxybenzoate 1 have been synthesized by Schiff base condensation of methyl 3,5-diformyl-4-hydroxybenzoate with o-aminophenol, which exhibits high selectivity and sensitivity toward Al3+. Fluorescence titration studies of receptors 1 with different metal cations in CH3OH medium showed highly selective and sensitive towards Al3+ ions even in the presence of other commonly coexisting metal ions. The detection limit of Al3+ ions is at the parts per billion level. Interestingly, the Al(III) complex of 1 offered a large Stokes shift (>120 nm), which can miximize the selfquenching effect. In addition, possible utilization of this receptor as bio-imaging fluorescent probe to detect Al3+ in human cervical HeLa cancer cell lines was also investigated by confocal fluorescence microscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel colorimetric and fluorescent chemosensor based on diaminopyrimidine (DAPCS) was designed and synthesized. • DAPCS was applied for the highly selective and ultra-sensitive detection of Cu2+ ion in aqueous media and living cell. • The probe DAPCS for Cu2+ showed a linear correlation, and LOD was calculated as 0.014 µM. • DAPCS-based test strips were fabricated and applied to the detection of Cu2+ ions in solutions. In this paper, a new and effective diaminopyrimidine-based chemosensor (DAPCS) was developed for the highly selective and ultra-sensitive detection of Cu2+ ion in aqueous media and living cell. Characterization and structure determining of DAPCS was determined by UV–Vis, FTIR and NMR analyses. It is observed that DAPCS and Cu (II) forms a ligand to metal charge transfer (LMCT) complex which produces distinguishable red color. The results also indicate that the DAPCS easily interacts with Cu2+ ion to form a 1:1 stoichiometry complex (DAPCS -Cu2+), resulting in a bathochromic shift in absorption maximum (429 nm to 449 nm) and remarkable quenching fluorescence intensity at the wavelength of 501 nm in DMSO-H 2 O solution. Furthermore, the detection limit of DAPCS towards Cu2+ was calculated to be 3.19 µM. Meanwhile, DAPCS was applied as fluorescent probe for detection of Cu2+ ions with the detection limit of 0.014 µM. The optimal pH range of probe DAPCS for quantitative analysis of Cu2+ ions was 9–11, which renders it suitable for detection of Cu2+ under physiological conditions. Additionally, the DAPCS could be applied to detect Cu2+ in real water samples and in HeLa cells, indicating the practical uses of DAPCS in real analyses. [ABSTRACT FROM AUTHOR]

Abstract: A novelty rhodamine B based chemosensor containing 2-amino-7-methyl-1, 8-naphthyridine moiety was designed and synthesized for colorimetric and fluorescent response on corresponding nucleoside polyphosphates through multi-hydrogen bond interaction in aqueous solution. The supramolecular recognition between the RBS and Cytidine-5′-diphosphate disodium hydrate (CDP) was investigated carefully: 1H nuclear magnetic resonance confirmed that the formation of multi-hydrogen bonds between naphthyridine moiety and the nucleoside base group could untie the spiro structure of RBS, and the ESI-MS spectra proved the formation of the 1:1 complexation species between RBS and CDP. The strong emission response of the RBS toward CDP and Adenosine-5′-triphosphate disodium trihydrate (ATP) ensures its application in living cells imaging. [Copyright &y& Elsevier]

Highlights: [•] A “turn-on” fluorescent chemosensor for the detection of Zn(II) was facilely synthesized. [•] Detection of Zn(II) can be performed in water at neutral pH with high sensitivity. [•] The chemosensor exhibits remarkably selective to Zn(II) over other metal ions. [•] The chemosensor could be efficiently delivered to live cells for bioimaging of Zn(II). [Copyright &y& Elsevier]

A novel highly selective and sensitive turn-on fluorescent chemosensor PCE to recognize Zn2+ has been developed. The sensor PCE displays a remarkable fluorescent enhancement at 456 nm (λ ex = 340 nm) with Zn2+ without the interference of other biologically important relevant metal ions in aqueous acetonitrile solution. Job's plot and mass spectral studies divulge such the interaction of PCE by Zn2+ was 1:1 binding stoichiometry. The association constant and detection limit of PCE to recognize Zn2+ was found to be 0.948 × 104 M−1 and 4.82 × 10−7 M respectively. The nature of turn-on fluorescence sensor was supported by TD-DFT calculations. And the synthesized probe PCE was able to image intracellular Zn2+ in living cells using confocal imaging techniques. PCE-Zn ensemble showed the remarkable fluorescence enhancement with ATP selectively among other biologically important phosphates. 31P NMR experiments suggesting that the triphosphates unit of ATP is intact with the PCE Zn. PCE-Zn ensemble can be utilized for monitoring ATP in live cells. [Display omitted] • Pyrene based Chemosensor for Zinc(II) ions. • turn-on fluorescence sensing of Zinc ions. • Distinguish between Zn(II) and Cd(II). • ICT based probe. • Applicable for imaging in live cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel pyrazoline fluorescent probe 1 was synthesized. • It can be used to detect Zn2+/ Cd2+ with high sensitivity and high selectivity. • It has good fluorescence reversibility. • It can be applied to fluorescent Zn2+/ Cd2+ imaging in living cells. A novel multi-response pyrazoline-based fluorescent probe 1 was designed and synthesized with a very simple molecular structure, which exhibited high sensitivity for detecting Zn2+ and Cd2+ in ethanol aqueous solution state based on the dissuasion of intramolecular charge transfer (ICT) and chelation-enhanced fluorescence (CHEF) effect. The binding modes of the complexes were determined to have 1:1 complexation stoichiometry and the binding constants were calculated to be 1.284 × 104 M−1 for Zn2+ and 4.313 × 103 M−1 for Cd2+ using the nonlinear curve-fitting method. Zn2+ and Cd2+ sensor have high anti-interference ability. Under optimal conditions, the detection limits were determined to be 0.9274 μM for Zn2+ and 0.8158 μM for Cd2+. Notably, the probe was found to have good biological compatibility and was employed to detect Zn2+/ Cd2+ in living Hela cells. [ABSTRACT FROM AUTHOR]

• Benzo-imidazo-pyrrolo[3,4-c] pyridines based fluorescent chemosensor for Fe2+ ion detection. • The chemosensor shows a high selectivity for Fe2+ over other common metal ions. • This chemosensor was successfully applied for imaging Fe2+ion in living hela cells. • The probe can be recycled and reused with good efficiency upto twenty cycles. A new fluorescent chemosensor with benzo-imidazo-pyrrolo[3,4-c] pyridines core was synthesized and characterized. The free chemosensor exhibited high fluorescence intensity with quantum yield (φ) of 0.498. The fluorescence intensity was quenched completely in the presence of iron over other common metal ions at physiological pH. The chemosensor formed 1:1 complex with iron and the quantum yield was determined to be 0.04 for the complex. Quenching mechanism of the chemosensor can be confirmed by various analytical methods such as UV–vis titration, Job plot and mass spectrometry analysis. DFT calculation of the complex was also carried out which confirmed the formation of complex between metal and chemosensor. Further, this chemosensor was applied for in vitro cell imaging in HeLa cells to illustrate that the chemosensor can be used as a fluorescent probe for monitoring Fe2+ in living cells. [Display omitted] [ABSTRACT FROM AUTHOR]

Highly sensitive and selectivite detection of copper ions (Cu2+) and hydrogen sulfide (H 2 S) have become important research topics due to the potential harmful impacts of these chemicals to human health and the environment. In this study, we report the synthesis of a dual-functional peptide-based probe L (FITC-AhxSerSerHis), designed to mimic a copper-sulfur metalloprotein, and capable of continuous detection of Cu2+ and S2- based on colorimetric and fluorescent methods. The new probe L displayed excellent "turn off" fluorescence response and good selectivity for Cu2+ ions via a modification of the tripeptide and fluorescein isothiocyanate group, and produced an obvious color change visible to the naked eye. Furthermore, as an excitable probe, the L -Cu complex could continuously detect S2- with high selectivity and sensitivity in 100% aqueous buffered solutions. The detection limits for fluorescence titration measurements, calculated using the equation 3σ/k, were 76.7 nM (Cu2+) and 27.2 nM (S2-), which were well below U.S. EPA safety levels. In addition, L could be cycled to alternately detect Cu2+ and S2-, thereby making it a promising reversible probe. Moreover, L was successfully applied to monitoring Cu2+ and S2- in live RKO cells through fluorescence imaging, exhibiting low cytotoxicity and good cell permeability. ga1 • Novelty peptide-based probe (L) was developed for Cu2+ and S2- with colorimetric and fluorescent. • The low detection limits of Cu2+ and S2- were 76.7 nM and 27.2 nM, respectively. • L could be recycled many times during the detection of Cu2+ and S2- as reversible probe. • L was successfully applied for sensing Cu2+ and S2- in living cells. [ABSTRACT FROM AUTHOR]

• The fluorogen with aggregation-induced emission has been designed and synthesized. • The AIEgen could be used for selective detection of hypochlorite. • The AIEgen could self-assemble in aqueous solution. • The AIEgen could be used for cell imaging and sensing hypochlorite in living cells. Fluorescent sensors have attracted great research attention for detection of various target substrates in environment and living organisms. However, there are still of some issues when using traditional organic probes owing to their poor water dispersibility and aggregation caused quenching effect. In this paper, we designed and synthesized an ionic fluorescent probe (named as TPY) with aggregation-induced emission (AIE) feature and explored its potential sensor performance towards hypochlorite in aqueous solution and living organisms. The results demonstrated that TPY can detect hypochlorite with excellent selectivity, outstanding sensitivity and fast response time. The reaction mechanism should be ascribed to the reaction between hypochlorite and TPY, that was evidenced by a number of characterization techniques, such as UV–vis/fluorescence spectroscopy, 1H NMR and mass spectroscopy. Most importantly, owing to its amphiphilicity and AIE feature, the probe could be well dispersed in aqueous solution and showed enhanced fluorescence, which endow it good sensor performance in both aqueous solution and living organisms. Finally, the biological assays confirmed that TPY has low toxicity and good biocompatibility, which could be used to detect hypochlorite in living cells. We trust this work will provide some new ideas for designing fluorescent probes with better performance for chemo/biosensors. [ABSTRACT FROM AUTHOR]

• A new pyrene based chemosensor has been synthesized with inexpensive and readily available materials. • The selective detection of Hg 2 2+ and Pb2+ was very quick. • The mechanistic pathway of detection Hg 2 2+ and Pb2+ was monitored through 1H NMR and HRMS. • The effect of metal ions towards probe was studied though CV and fluorescence bio imaging. We developed and synthesized dimeric pyrene with pyridine unit based metal biding fluorescent probe to screen sequence of metal ions. The analyzed pattern showed a clear distinction of responsive and non-responsive metal ions. From the successful experiment, we found that the synthesized probe is selectively responsive to Hg 2 2+ and Pb2+ ions through both visually and optically. This is the first fluorescent chemosensor for Hg 2 2+ based on pyrene. The quantitative aspects of the detection process has been calculated by absorption, emission, lifetime decay and quantum yield study. Eventually, using confocal laser scanning microscopy experiments we attempted to testify the drastic changes in bacterial intracellular cells by inducing fluorescence emission by the combination of the probe with Hg 2 2+ and similarly probe with Pb2+. [ABSTRACT FROM AUTHOR]

A new naphthyl hydrazone anchored nitrosalicyl unit has been developed as a host for the selective and sensitive detection of Ag+, Hg2+ and F− ions in DMSO/water (9:1) medium. An obvious fluorescence enhancement was observed towards Ag+, Hg2+ and F− ions due to the inhibition of both photoinduced electron transfer (PET) process and C N isomerization phenomenon. Moreover, the binding stoichiometry of probe with Ag+, Hg2+ and F− ions was established based on Job's plot, 1H NMR, 19F NMR titrations and ESI-MS analysis. Furthermore, the sensing behavior of probe for Ag+, Hg2+ and F− ions was supported by Density Functional Theory (DFT) calculations. Besides, cell viability of the probe was demonstrated using live cell imaging experiment and the probe is proved to be an excellent chemical tool for mapping F− and Ag+ ions distribution in HeLa cells and Zebrafish embryos respectively in biological environments. • We reported a new naphthyl hydrazone anchored salicyl unit for the detection of Ag+/Hg2+/F− ions in DMSO/H 2 O (9:1 v/v) medium. • The binding ratio of ghost/guest was confirmed by Job's plot, 1H NMR titration, 19F NMR and ESI-MS analysis. • The probe has followed the inhibition of both PET and C N isomerization mechanistic pathway for sensing analytes. • The sensing mechanism was supported by DFT calculations. • The cell viability of the probe was demonstrated via live cell imaging experiments. [ABSTRACT FROM AUTHOR]

A new near-infrared fluorescent probe (OTA-DCM), which contained a conjugated dicyanomethylene-benzopyran structure as the near-infrared fluorophore and dithia-dioxa-monoaza crown ether moiety as the receptor, was developed as a "naked-eye" indicator for Hg2+ with rapid response, good binding constant (1.05 × 104 M−1), high selectivity and sensitivity. Moreover, OTA-DCM was successfully employed in real aqueous samples and fluorescent imaging for detection of Hg2+ in living cells and zebrafish larvae with low cytotoxicity. • A new near-infrared fluorescent probe (OTA-DCM) was developed as a "naked-eye" indicator for Hg2+. • The probe detected Hg2+ with rapid response, good binding constant (1.05 × 104 M−1), high selectivity and sensitivity. • The probe was employed in real aqueous samples and fluorescent imaging for detection of Hg2+ in living cells and zebrafish larvae with low cytotoxicity. [ABSTRACT FROM AUTHOR]

• An "off-on" fluorescein-based chemodosimeter probe 1 for the recognition of Cys was designed and developed. • Probe 1 exhibited rapid, highly selective and sensitive for determination Cys over Hcy and GSH. • The recognition mechanism was studied by spectroscopy titrations, mass spectra determination and DFT calculations. • Fluorescence cell imaging demonstrated that probe 1 could detect Cys in HeLa cells. A novel chromogenic and fluorescent sensor based on semiacenaphthenofluorescein (Probe 1) was designed and synthesized. This probe exhibited superior selectivity and sensitivity for cysteine (Cys) over other analogues, such as homocysteine and glutathione, and the corresponding detection limit was 0.086 μM, which was much lower than intracellular concentration. The tandem conjugate addition/cyclization sequence mechanism was revealed by mass spectrometry, 1H NMR examination and density functional theory (DFT) calculations. Finally, the results of photostability, cell imaging and viability assays showed that the probe possessed excellent membrane permeability, hypotoxicity and fluorescent imaging of cysteine, which indicated its potential applications in living cells. [ABSTRACT FROM AUTHOR]

A novel click-derived monostyryl BODIPY-based fluorescent probe has been prepared. Notably, upon exposure to Hg2+ or Cu2+, it exhibited remarkable blue-shifted absorptions from 592 to either 555 for Hg2+ or 502 nm for Cu2+ with distinct color changes from blue to purple for Hg2+ or yellow for Cu2+ in CH 3 CN/H 2 O. Interestingly, its fluorescence showed significant ratiometric (Hg2+) and ON-OFF (Cu2+) changes. Notably, the probe displayed ratiometric fluorescence from 690 to 602 nm with a 65-fold enhancement in fluorescence ratio of I 602 /I 690 for Hg2+ and underwent a substantial ON-OFF fluorescence for Cu2+. Furthermore, this probe was successfully used in Hela cells and could easily discriminate Hg2+ and Cu2+ through double-channel imaging. These overall results illustrate that this monostyryl BODIPY potentially serves as a remarkable colorimetric probe for fluorescent ratiometric and ON-OFF discriminative detection of Hg2+ and Cu2+ in solutions and living cells by a remarkable double-channel change. Image 1 • A novel monostyryl BODIPY-based probe was prepared through click reaction. • Colorimetric changes from blue to purple for Hg2+ or yellow for Cu2+ were easily seen. • It showed large ratiometric for Hg2+ and ON-OFF for Cu2+ fluorescence. • It successfully distinguished Hg2+ and Cu2+ in living cells by double-channel imaging. • A 37-fold enhanced ratio for Hg2+ and a sufficient quenching for Cu2+ were seen in cells. [ABSTRACT FROM AUTHOR]