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[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] • A Zn2+ selective turn-on optical sensor (DIH) with ESIPT process was reported. • DIH showed high selectivity and sensitivity Zn2+ over other metal ions tested. • The detection mechanism was elucidated by ESI–MS, NMR and DFT calculations. • The sensor is suitable for imaging Zn2+ in living cells. Zinc ions (Zn2+) play a significant role in our daily lives and production, which is related to human health and environment protection. Therefore, it is crucial in this field to develop sensors with improved analyte selectivity and sensitivity. We prepared a fluorescent sensor, DIH, through the reaction of 5-(tert -butyl)-2-hydroxyisophthalaldehyde with isonicotinohydrazide. DIH, in free form, can undergo excited state intramolecular proton transfer (ESIPT) process upon excitation. Among a wide range of metal ions tested, only Zn2+ inhibited this ESIPT process, resulting in an increase in fluorescence intensity (13.3-fold) with chelation enhancement fluorescence process (CHEF). The complex (DIH/Zn2+) stoichiometry was determined to be 1:1 and the binding constant of the complex was estimated as 3.18 × 107 M−1. DIH could also be applied to detect zinc ions down to a low concentration level of 11.2 nanomolar with fluorescence spectroscopy. Moreover, the cytotoxicity evaluation of DIH against human colon adenocarcinoma cells lines demonstrated that the sensor was nontoxic and could be used successfully in cellular imaging. [ABSTRACT FROM AUTHOR]

Abstract We present here the synthesis of a simple and low-cost Schiff base chemosensor (HL) for selective detection of both Zn(II) and Cu(II) ions in HEPES buffer pH = 7.4. The chemosensor HL exhibits quick response through fluorescence and colorimetric changes for both Zn(II) and Cu (II) ions as examined by fluorescence and absorption titrations. Both the metal ions form 1:1L– Zn(II) (complex 1) and 1:1L– Cu(II) (complex 2) complexes, confirmed by Job's Plot. We are successful to elucidate the structure of complex 1 through X-ray diffraction analysis. Reversibility of the chemosensor in its binding with Zn(II) and Cu (II) ions separately is also examined in presence of Na 2 EDTA solution. The enhancement of fluorescence intensity of the chemosensor is based on the chelation-enhanced fluorescence (CHEF) effect of L–Zn(II) with the inhibition of both photoinduced electron transfer (PET) effect and C˭N isomerization in excited state and the quenching effect is due to the paramagnetic nature of Cu(II) to the L–Zn(II) system. Furthermore, the geometry and spectral property of HL and both the metal complexes have been studied by DFT, TD-DFT calculations. The limit of detection (LOD) values of both the ions are 2.29 × 10-9 M and 3.67 × 10-9 M, respectively. These values clearly suggests that HL is a promising chemosensor in monitoring Zn(II) and Cu(II) ions in the biological and environmental study with excellent accuracy and precision. The propensity of the chemosensor to detect intracellular Cu(II) and Zn(II) ions in Candida albicans cell lines by fluorescence imaging is also demonstrated in this study. Furthermore, molecular logic gates have been developed based on the idea where chemically encoded information as the input is converted into fluorescent signals as the output. In this work, the designed fluorescent chemosensor exhibits dual logic gates (XOR, AND) involving Zn(II), Cu(II) and Na 2 EDTA. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

[Display omitted] • A chemosensor probe HL based on pyrimidine was designed and synthesized. • The chemosensory behaviour of HL was determined by fluorescence spectroscopy. • HL was found to selectively recognise Zn+2 ions over other metal ions. • The probe HL showed a low detection limit (LOD) of 0.4 nM for Zn2+. • For cell imaging and sensing Zn2+-induced PrP (106–126) aggregation, HL was used. Zinc is one of the most vital components of the living system and is also involved in promoting various neurodegenerative diseases. Therefore, direct monitoring of Zn2+ in biological systems is essential for human well-being. In this work, a chemosensor probe (HL) based on pyridine was synthesised, characterised, and reported for its highly efficient recognition of the zinc ions. The chemosensing behaviour of HL was determined by fluorescence spectroscopy. The probe was extremely sensitive for Zn2+, with an intensity enhancement of over 80-fold and a low detection limit (LOD) of 4 × 10-10 M (0.4 nM), which is remarkably low. In the presence of Co2+, Cr3+, and Cu2+ metal ions, HL shows fluorescence quenching, probably due to their paramagnetic nature. This chemosensor probe was used for applications in cell imaging and sensing of the Zn2+-induced prion (PrP 106-126) peptide aggregation. [ABSTRACT FROM AUTHOR]

An acylhydrazone-based derivative, 3-hydroxy-N'-(2-hydroxy-1-naphthalene methylene)-2-naphthalene hydrazide (H 3 L), was synthesized and characterized by elemental analyses, IR, 1 H NMR and mass spectrum. H 3 L is non-fluorescent in DMSO. But the fluorescence emission is enhanced obviously via the formation of aggregates in DMSO/H 2 O mixture. The formed aggregates were confirmed by DLS and SEM. H 3 L is an aggregation-induced emission (AIE)-active fluorophore. H 3 L can act as a fluorescence sensor for Al 3+ and Zn 2+ in DMSO/H 2 O (v/v, 9/1) and THF/H 2 O (v/v, 999/1), respectively. And H 3 L is also a naked-eye probe for Fe 3+ in DMSO/H 2 O (v/v, 9/1). The binding stoichiometry of H 3 L to both Al 3+ and Zn 2+ is 1:1, but that to Fe 3+ is 2:1. The metal complex species formed in the detection procedure are deduced by Job plot, spectroscopic titrations and ESI–MS to be [AlL(DMSO) 2 ], [Zn(HL)(H 2 O)] and [Fe(HL)(H 2 L)]. The detection limit is as low as 3.66 μM for Al 3+ , 1.01 μM for Zn 2+ and 0.34 μM for Fe 3+ . H 3 L can also be used to detect intracellular Al 3+ and Zn 2+ . The sensing event might be attributed to a combinational effect of excited state intramolecular proton transfer (ESIPT) and chelation-enhanced fluorescence (CHEF) mechanism for selective detection of Al 3+ and Zn 2+ ions, and ligand-metal charge transfer (LMCT) mechanism for Fe 3+ ion. [ABSTRACT FROM AUTHOR]

A new simple quinoline-based chemosensor 1 was synthesized for Zn 2+ . 1 showed the selective fluorescence enhancement in the presence of Zn 2+ with a 1:1 stoichiometry in a near-perfect aqueous solution (bis-tris buffer:DMSO = 999:1), which was reversible with the addition of ethylenediaminetetraacetic acid (EDTA). The detection limit (0.6 μM) of 1 for Zn 2+ was much lower than World Health Organization guideline (76 μM) in drinking water. 1 was successfully applied to quantify and image Zn 2+ in water samples, test kit and living cells. The sensing mechanism of Zn 2+ by 1 via the intramolecular charge transfer was explained by theoretical calculations. [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]

The selective fluorescence zinc(II) sensing properties of a Schiff-base compound, 2-methoxy-6-(2-morpholinoethyliminomethyl)phenol (HL) have been explored. The emission intensity of HL in the presence of one equivalent of Zn 2+ ion increases by about 25 times. Several other metal ions, except Cd 2+ and Ni 2+ , have not been able to increase the emission intensity of HL significantly. The quantum yield and life-time of HL have also been increased in the presence of Zn 2+ ions. The enhancement in fluorescence intensity of HL is mainly due to the restriction of ESIPT, CHEF and PET on complex formation. HL forms a complex with Zn 2+ in 1:1 ratio as evidenced by Job's plot analysis and X-ray single crystal structure determination. Some theoretical calculations have been performed to get a better view on the nature of the observed electronic transitions. The probe has been applied for imaging of DLD-1, human colorectal adenocarcinoma cell. [ABSTRACT FROM AUTHOR]

• 2, 4-dinitrophenyl hydrazine based Schiff-base (L) was synthesized. • The fluorescence of L corresponds to excited state intra-molecular proton transfer (ESIPT) emission. • The intriguing chemo-sensing properties of L were evaluated by fluorescence studies. • The L-Zn2+ complex formation is reversible upon addition of strong chelating agent EDTA. • The probe L is highly selective for Zn2+ in DMSO-H 2 O and living Hela cell. • The probe L is the first molecule, which is highly selective sensor for Zn2+ in solid phase. Luminescent chemosensors based on Schiff bases have drawn tremendous research interest owing to their easy synthesis, enriched photophysical properties, and potential applications in biology and materials science. A dinitrophenyl-based Schiff base molecular probe (L) was synthesized and characterized to estimate its selective detection of Zn2+. The probe L exhibits weak emission in the DMSO-H 2 O solvent mixture due to excited-state intramolecular proton transfer (ESIPT). Interestingly, fluorescence is enhanced with the addition of Zn2+ to the DMSO-H 2 O solution of L , whereas the emission remains unchanged with the addition of other ions. This specifies that probe L acts as a selective chemosensor for Zn2+. The binding stoichiometry for the L : Zn2+ complex is 1:1, which was calculated using the Benesi-Hildebrand plot from fluorescence data. Furthermore, the binding modes are also supported by density functional theory (DFT) calculation. The binding constant and detection limits are 6.35 × 107 M−1 and 1.1 × 10−8 M, respectively. The L-Zn2+ complex formation is reversible upon the addition of a strong chelating EDTA ligand. In addition, L is also used to detect Zn2+ in living Hela cells and selective sensing of Zn2+ in the solid phase. [Display omitted] [ABSTRACT FROM AUTHOR]

Mitochondria-targetable fluorescent chemosensors, Rhodamine-B and rhodamine 6G bearing syringaldehyde based receptors were designed and synthesized for efficient chemosensing of Zinc(II) ions. The probes showed the very selective naked eye color change to pink from colorless upon addition of Zinc(II) ions, further these probes showing turn-on fluorescence enhancement with Zn(II) ions by opening of rhodamine spirolactam. The probes are very sensitive towards Zn(II) ions among other ions. These probes RBS and R6S will be applicable to detect zinc ions upto the low level concentration 0.18 and 0.19 nano molar respectively. The affinity of these sensors RBS and R6S for Zinc (II) ions was found to be in the range of 1.12 × 104 M−1 and 7.28 × 104 M−1 respectively. 1H-nmr titrations of the probes with Zn(II) ions clearly indicating the spiroring opening of the spirolactam. DFT calculations supporting that the perceived photophysical changes of the probes on appendage of the zinc ions. Probes RBS and R6S are useable for selective staining mitochondria. Both of the probes are applicable to reveal labile Zn(II) in live Hela and MCF-7 cells via fluorescence imaging. RBS and R6S are also finding application on quantification of Zinc(II) ions inside mitochondria via fluorescence imaging. [Display omitted] • Rhodamine dye derived sensor for Zinc(II) ions • Colorimetric changes detectable using Naked eyes • NMR titrations showing spiroring opening • Applicable for live cell imaging via fluorescence imaging. [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]

The synthesis and evaluation of new quinoline based fluorescent chemosensor L1 for the detection of Zn 2+ in THF/H 2 O. The absorption and fluorescent spectra change was observed upon addition of Zn 2+ indicate that L1 is highly selective for Zn 2+ over other metal ions. The probe displayed an apparent color change while addition of Zn 2+ , which could be observed by the naked eye under a UV lamp. The experimental results have been verified with DFT and TDDFT calculation. In vitro sensitivity to Zn 2+ was demonstrated in Hela cells with the use of fluorescence confocal microscopy. [ABSTRACT FROM AUTHOR]

A simple coumarin based sensor 1 has been synthesized from the condensation reaction of 7-hydroxycoumarin and ethylenediamine via the intermediate 7-hydroxy-8-aldehyde-coumarin. As a multiple analysis sensor, 1 can monitor Zn 2+ with the fluorescence enhanced at 457 nm, and ratiometric detection at 290 nm, 350 nm and 420 nm in DMF/H 2 O (1/4, v/v) medium. Sensor 1 can also monitor Mg 2+ with the fluorescence enhanced at 430 nm, and ratiometric detection at 290 nm, 370 nm and 430 nm in DMF medium through the interaction of chelation enhance fluorescence (CHEF) with metal ions. Furthermore, 1 also can monitor F − with the fluorescence enhanced at 460 nm, and ratiometric detection at 290 nm and 390 nm in DMF medium simultaneously via hydrogen bonding and deprotonation with F − anion. Spectral titration, isothermal titration calorimetry and mass spectrometry revealed that the sensor formed a 1:1 complex with Mg 2+ , Zn 2+ or F - , with stability constants of 4.5 × 10 6 , 3.4 × 10 6 , 8.0 × 10 4 M −1 respectively. The complexation of the ions by 1 was an exothermic reaction driven by entropy processes. Furthermore, the sensor exhibits good membrane-permeability and was capable of monitoring at the intracellular Zn 2+ level in living cells. [ABSTRACT FROM AUTHOR]

A new turn-on fluorescent quinolone tetrazole based chemosensor (QT-1) is designed and synthesized which shows high sensitivity and selectivity for Zn 2+ ions in aqueous acetonitrile solution. QT-1 probe easily distinguishes Zn 2+ ions from Cd 2+ ions. Job's plot analysis suggested that the binding of QT-1 and Zn 2+ ions is probably a 1:1 stoichiometry. Thus QT-1 can be employed for fluorescent imaging of Zn 2+ ions in living cells. [ABSTRACT FROM AUTHOR]

A novel Zn 2+ ion chemosensor 1 has been developed based on deoxycholic acid and salen motifs, and this chemosensor can be used in test-strips and living cells imaging for Zn 2+ ion through a turn-on effect. Moreover, the resulting [ 1 ·Zn 2+ ] complex exhibits turn-off response toward H 2 PO 4 − ion, thus leading to the fabrication of an INHIBIT (INH) logic gate using Zn 2+ ion and H 2 PO 4 − ion as inputs and the emission of 1 as outputs, respectively. This line of research not only enriches the library of Zn 2+ ion sensors, but also expands the applications of natural products-based chemosensors. [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]

A highly sensitive and selective quinoline based reversible chemosensor (HL) for the efficient detection of Zn 2+ has been developed. The synthesized chemosensor HL is highly efficient in detecting Zn 2+ over other metal ions commonly obtained in physiological and environmental samples. HL shows fluorescence ‘turn-on’ response with 53 fold enhancement of emission intensity in presence of Zn 2+ . The limit of detection is 5.0 × 10 −9 M. HL is efficient in detecting Zn 2+ intracellularly and also exhibits an INHIBIT logic gate with Zn 2+ and EDTA as chemical inputs by monitoring the emission mode. Electronic structure and sensing mechanism have been interpreted by DFT and TDDFT calculations. [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]

A new Zn2+ selective chemosensor (3) was synthesized by condensation of commercially available substituted salicylaldehyde and isonicotinohydrazide, and characterized by single crystal X-ray crystallography. Receptor 3 with Zn2+ exhibited a highly selective and pronounced enhancement in the fluorescence emission among different cations by forming a 2:1 complex. The receptor can detect Zn2+ up to nanomolar level (6.75nM) with good tolerance of other metal ions and can be used for in vitro cellular imaging. [ABSTRACT FROM AUTHOR]

Abstract: Time-resolved luminescence detection technique using lanthanide chelates as luminescent probes or sensors is a highly sensitive and widely used tool for the luminescence detections of various biological and bioactive molecules. The essential of this technique is the developments of various functional luminescent probes or sensors that can selectively recognize the biological targets. In this work, a dual-chelating ligand N,N,N1,N1-{2,6-bis(3′-aminomethyl-1′-pyrazolyl)-4-[N,N-bis(2-picolyl)amino-methylenepyridine]} tetrakis(acetic acid) (BBATA) has been designed and synthesized. The luminescence of its Tb3+ chelate is very weak, but can be selectively and strongly enhanced upon reaction with Zn2+ ions. Thus a Tb3+ chelate-based luminescent chemosensor, BBATA-Tb3+, for highly selective and sensitive time-resolved luminescence detection of Zn2+ ions was developed. To confirm the utility of new chemosensor for the detection of intracellular Zn2+ ions, the performance of BBATA-Tb3+ as a chemosensor for time-resolved luminescent imaging detection of Zn2+ ions in living cells was investigated. The results demonstrated the efficacy and advantage of the new luminescent chemosensor for time-resolved luminescence detection of intracellular Zn2+ ions. [Copyright &y& Elsevier]

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]