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An indene-chalcone-based fluorescence probe 1 was synthesized and characterized. Under physiological conditions (containing 5% DMSO), probe 1 showed satisfactory stability with a low background signal and recognized carboxylesterases (CEs) based on the catalytic hydrolysis of ester groups, releasing a significant green fluorescence. Probe 1 presents several features including a short response time (within 20 min), low detection limit (1.3 × 10

A fluorescence-enhanced and lysosome-targeted Al3+ probe (1) based on a pyrazole-containing hydrazone was developed in this work. The fluorescent probe 1 displays an OFF–ON fluorescence response to Al3+ in the lysosome pH environment. In addition, the resultant 1–Al3+ complex could act as an ON–OFF fluorescence sensor for F−. Fluorescence imaging shows that 1 is suitable for visualization of Al3+ in lysosomes of HeLa cells.

A novel pyrazine hydrazone 1 has been designed and synthesized, which acts as a multiprobe for selective detection of Al3+, Mg2+, and Zn2+ in DMSO solution based on fluorescent enhancement with three different emission colors. The higher affinity of 1 toward Al3+ and Zn2+ compared with Mg2+ facilitates the establishment of a simple ratiometric fluorescent method for the detection of Al3+ and Zn2+ based on the 1 + Mg2+ system. Conversely, probe 1 selectively recognized Al3+ in DMSO-H2O cosolvent with a turn-on response, and the resultant 1 + Al3+ complex could determine F− via a fluorescence quenching signal. In addition, the probe is applied for imaging of Al3+ and F− in living cells.

Hypochlorite plays a significant role in physiological processes, particularly regulation of lysosomal functions, and is involved in various diseases. Thus, it is crucial to develop highly sensitive and selective molecule tools to detect HClO in lysosomes. Herein, a novel 2H-benzo[h]chromene-pyridine derivative (1) was synthesized through condensation reaction, which exhibited a notable deep-red emission at 640 nm in pure water. This deep-red emission was specifically quenched by adding ClO−. The response of probe 1 toward ClO− was rapid (within 10 s), sensitive (detection limit of 0.012 μM), and effective over a wide range of pH (1.0–12.0). Due to the existence of morpholine as the lysosome-targeting unit, the probe was successfully utilized to monitor lysosomal ClO−. Moreover, the probe 1 was also applied to detecting ClO− in zebrafish.

A rhodamine hydrazone 1 bearing coumarin moiety was designed and prepared. Compound 1 exhibited high selectivity toward Co2+ and trivalent metal ions with fluorescence enhancement in CH3OH solution. However, 1 selectively responded to Al3+ in nearly pure H2O media and was further applied to monitor Al3+ in live cells. Moreover, 1 could also act as a colorimetric probe toward Cu2+ in either CH3OH or H2O solution. In addition, sensor 1 displayed aggregation-induced ratiometric emission (AIRE) activities in mixed H2O/CH3OH solution.

A simple asymmetric hydrazone 1 based on salicylaldehyde was designed and prepared, and exhibited an evident aggregation-induced emission (AIE) at a long wavelength of 570 nm in aqueous medium. Probe 1 can selectively sense Al3+ in CH3OH solution through the chelation-enhanced fluorescence mechanism and also recognize Cu2+ via fluorescence quenching in H2O solution through the Cu2+-induced assembly of aggregates. In addition, the probe can be applied for detecting Cu2+ in biological samples.

A novel rhodamine-based Schiff base derivative was obtained via the simple condensation of substituted formyl-1H-pyrrole and rhodamine 6G hydrazone. Fluorescence resonance energy transfer enabled the subsequent use of the derivative as a naked-eye colorimetric and ratiometric fluorescent sensor for Cu2+ in semi-aqueous solution, and the existence of the morpholine group enabled the further application of the sensor in imaging Cu2+ in the lysosomes of HeLa cells.

The hydrazone sensor (1) derived from pyrazine-2-carbohydrazide and 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) was applied to the fluorescent “turn-on” detection of Al3+ in semi-aqueous solutions. The strongly emissive 1+Al3+ complex could identify F− among other tested anions. The detection limits of sensor 1 for Al3+ and F− were 0.18 and 0.20 μM, respectively, which are both much lower than the corresponding values recommended by the World Health Organization, namely, 7.41 and 79 μM. Several spectral methods, including single crystal X-ray analysis for the crystal structures of the Cu2+ and Ni2+ complexes of sensor 1, as well as the density-functional theory method, were used to elucidate the binding mode between the sensor and Al3+. 1 can also be used for a selective sensor to continuously monitor Al3+ and F− in living cells.

A simple hydrazone probe (1) was designed and synthesized for the successive detection of Al3+ and pyrophosphate (PPi) in almost 100% buffer environment. The probe provided O2N donor set for chelation with Al3+, leading to a distinct fluorescence boost at 510 nm. The in-situ formed 1-Al3+ complex detected PPi with an “on-off” behavior. The detection limits for Al3+ and PPi were 35.7 nM and 76 nM, respectively. Benefiting from the existence of morpholine as lysosome-targeting group, probe 1 was successfully applied to the detection of Al3+ and PPi in lysosomes.

A simple water soluble hydrazone sensor (1·Cl) has been developed to selectively chelate with Zn2+ via an O2N donor set, leading to specific fluorescence enhancements. The highly emissive 1-Zn2+ complex can serve as a reversible on-off sensor for S2−. The detection limits of 1·Cl for Zn2+ and S2− are 66.0 and 32.6 nM, respectively. The recognition mechanism was carefully investigated through FL, UV-vis, 1H NMR, ESI-MS, time-resolved fluorescence, and density functional theory (DFT) calculations. Owing to the mitochondria-targeting ability of the terminal quaternary ammonium moiety, 1·Cl was successfully applied to image mitochondrial Zn2+ and S2−.

A water-soluble salicylaldehyde-based thiosemicarbazone has been designed and applied to the selective fluorescent turn-off detection of Hg2+ ions. The probe-Hg2+ system acted as a turn-on probe toward biothiols, including cysteine, homocysteine, and glutathione. The limits of detection of the probe toward Hg2+, cysteine, homocysteine, and glutathione are 0.52 μM, 0.74 μM, 0.31 μM, and 0.27 μM, respectively. The mechanisms are carefully confirmed by fluorescence spectrometry, UV-visible spectrometry, electrospray ionization mass spectra, hydrogen nuclear magnetic resonance, time-resolved fluorescence spectrum, and density functional theory calculation. Moreover, due to the presence of a morpholine group, the probe was successfully used to monitor Hg2+ and biothiols in the lysosomes of HeLa cells.

A simple monocarbazone 1 derived from 2H-benzo[h]chromene-3-carbaldehyde and carbazide exhibited aggregation-induced ratiometric emission upon the addition of water to CH3OH solution (Δλem= 30 nm). Upon Cu2+ treatment, the fluorescence emission of 1 displayed a significant red shift in both CH3OH and H2O solutions. In addition, 1 can detect Hg2+ through the fluorescence quenching in H2O solution. The response mechanism to Cu2+ involved an intermolecular charge transfer coupled with a metal-induced assembly, whereas that to Hg2+ was probably due to a photo-induced electron transfer coupled with metal-induced assembly, which were thoroughly investigated by spectral methods and theoretical calculation. In addition, the sensor could successfully detect the corresponding ions in HeLa cells.

A simple Schiff-base fluorescent chemosensor (1) was synthesized by the reaction of 3-amino-pyrazine-2-carbohydrazide and 7-diethylamino-3-formylcoumarin; the sensor 1 displayed a notable green emission at 524 nm in DMSO and an aggregation-induced ratiometric emission (AIRE) at 555 nm in an almost buffered aqueous media (0.5% DMSO content). The AIRE of 1 was quenched following binding to Zn2+ ions, while the fluorescence emission in the far-red region was evidently enhanced at 628 nm. Notably, the ratiometric signal output could be utilized to specifically distinguish Zn2+ among various metal ions. Moreover, the 1-Zn2+ complex was effectively employed as a fluorescent ratiometric chemosensor for pyrophosphate (PPi) detection. The detection limit was 3.52 μM and 2.45 μM for Zn2+ and PPi, respectively. The binding mechanism was evaluated by 1H NMR, ESI-MS, single-crystal X-ray diffraction, TEM, time-resolved fluorescence spectrophotometry, and density functional theory studies. Overall, owing to its sensitive fluorescence behavior, cell imaging studies demonstrated that this sensor is capable of sensing Zn2+ and PPi in living cells.

In this study, we developed a fluorescence-enhanced probe (1) based on a simple Schiff-based condensation reaction for Cu2+ selection. We investigated its distinct recognition mechanism through mass spectra, 1H NMR studies, and DFT calculations. The imaging and costaining experiments indicated that the probe could successfully image lysosomal Cu2+.

A morpholine-functionalized pyrrole-cyanine probe was synthesized via a simple condensation reaction in high yield. This probe exhibits high selectivity toward ClO− on fluorescence and UV–vis spectra in neat aqueous solution. The strong green emission of the probe solution was quenched and the yellow color faded immediately upon the addition of ClO−. The detection limit of the probe for ClO− was 0.165 μM. The mechanism of hypochlorite-induced C C breakage was supposed on the basis of EIS-MS, NMR, and density functional theory (DFT) calculation. Finally, the probe was utilized to image ClO− in lysosomes of living cells.

A novel pyrene-based Schiff base derivative, 1, was synthesized by one-pot reaction. This compound was then used for aggregation emission enhancement and as fluorescence turn-on sensor toward Cu2+ in semi-aqueous solution based on metal-induced self-assembly. Detection limit of Cu2+ ion was 35 nM. The fluorescent sensor was further applied in monitoring intracellular Cu2+ in HeLa cells.

An aggregation-induced emission (AIE) active bis-hydrazone in the aqueous medium is designed and prepared, which can be used as a multi-probe that selectively detects Cu2+, Zn2+, and Hg2+ by monitoring the changes in absorption and fluorescence spectral patterns. Results show that Zn2+ and Hg2+ can enhance the fluorescence in EtOH solution. The addition of Cu2+ strongly improves absorption in the visible range. In contrast to the fluorescence of 1 + Zn2+, the fluorescence of 1 + Hg2+ can be maintained in the presence of water. The crystal structure of the Hg(II) complex based on 1 is further determined through X-ray crystallographic analysis. To test the practical use of the probe, the determination of Hg2+ in real water samples was also evaluated.

A novel turn-on fluorescent probe containing a benzoxazole fluorophore has been synthesised and its response to different metal ions has been investigated by spectrometry. The probe was highly selective and sensitive to Zn2+ and showed a complexation ratio towards Zn2+ of 1:1. It also exhibited a linear response range for Zn2+ from 0.3 to 4.8 μmol L−1 with a detection limit of 0.36 μmol L−1.

A new colorimetric and fluorescence molecular chemosensor based on triazole hydrazone can be used as a multi-probe for selective detection of Al3+, Zn2+, and Cu2+ by monitoring changes in the absorption and fluorescence spectral patterns. Results show that Al3+ and Zn2+ ions can induce remarkable fluorescence enhancement at pH 6.0 and pH 10.0, respectively, while the addition of Cu2+ ions leads to a significant UV-visible absorption enhancement in the visible range at pH 6.0. In addition, the resultant Al3+ complex could act as an ‘on–off’ fluorescence sensor for F−. The fluorescence sensor was also used to monitor intracellular Al3+, Zn2+, and F− in Hela cells.

A simple chemosensor, namely, N-((quinolin-8-yl)methylene)acetohydrazide (1) was synthesized and used as an off–on fluorescence sensor, which exhibits high selectivity toward Zn2 + in aqueous media. The probe has large Stokes shift of > 200 nm, and its detection limit for Zn2 + is 89.3 nM. The binding process was confirmed through UV–vis absorption analysis, fluorescence measurements, mass spectroscopy study, 1H NMR spectra and density functional theory calculation. The crystal structures of Zn2 +, Ni2 +, and Cu2 + complexes based on 1 were determined through X-ray crystallographic analysis. The fluorescent probe was then applied to monitor intracellular Zn2 + in HeLa cells.

A 1,8-naphthalimide hydrazone derivative bearing a pyrrole unit is a highly selective ratiometric fluorescent Cu 2+ probe used to monitor intracellular Cu 2+ in HeLa cells. This probe functions via a unique hydrolysis mechanism through Cu 2+ -promoted electrophilic substitution. Binding is confirmed through UV–vis absorption, fluorescence measurements, mass spectroscopy, IR, X-ray single crystal diffraction, and DFT calculation.

A new morpholine functionalized coumarin-based fluorescent probe 1 was easily synthesized. The probe realized the sequentially detecting of Cu2+ and H2S in the HEPES buffer solution (20 mM, pH = 5.0). It made a turn-off fluorescence response to Cu2+ by using a complex formation with a 2:1 binding mode, and the resulting complex was able to detect H2S according to the displacement approach with a turn-on fluorescence response. The detecting limits of probe 1 for Cu2+ and 1–Cu2+ system for H2S were calculated to be 26 nM and 88.5 nM, respectively. This “on-off-on” recognition process was demonstrated by ultraviolet–visible spectroscopy, fluorescence spectroscopy, using proton nuclear magnetic resonance studies, electrospray ionization mass spectroscopy, single crystal X-ray diffraction, and using density functional theory calculations. In addition, both cell imaging and co-staining experiments showed that the probe could be utilized to visually detect Cu2+ and H2S in lysosomes.

Chemosensor C1, namely, 3-acetoacetyl-7-hydroxycoumarin, was synthesized and exhibited highly selective and sensitive fluorescence sensing ability for Cu2+ over other metal ions under physiological conditions. The fluorescence quenching response of C1 for Cu2+ indicated that C1 can be used as an on-off fluorescent chemosensor to selectively detect Cu2+. The binding process was confirmed by UV–vis absorption, fluorescence measurement, mass spectroscopy, IR spectra and DFT calculation. To test the practical use of the probe, the determination of Cu2+ in real water samples was evaluated. The application of the fluorescent probe in monitoring intracellular Cu2+ in HeLa cells has also been demonstrated.

A rhodamine-2-thioxoquinazolin-4-one derivative ( R1 ) has been synthesized by an addition-elimination reaction of rhodamine 6G ethylenediamine with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Fe 3+ under physiological conditions. Moreover, R1 could sense Fe 3+ by “naked eye” with a color change from colorless to yellow. To test the practical use of the probe, the determination of Fe 3+ in real water samples was evaluated. The application of the fluorescent sensor in monitoring intracellular Fe 3+ in glioma cell line U251 has also been demonstrated. In addition, single crystal structures of R1 ·1·5H 2 O·0·5CH 3 CN, as well as the possible intermediate of R1 with Ag + and Hg 2+ ions were reported.

A rhodamine derivative (R1) has been synthesized by an additive reaction of rhodamine 6G hydrazide with methyl 2-isothiocyanatobenzoate, which exhibits high selectivity and sensitivity as a fluorescent sensor toward Cu2+ under physiological conditions. The detection limit of Cu2+ ion is 47.2 nM. Moreover, R1 could sense Cu2+ by “naked eye” with a color change from colorless to pink. This selective signaling behavior is not affected by other canions that might be present in the environmental samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in HeLa cells was also demonstrated.

A rhodamine derivative was synthesised via the hydrazone formation of rhodamine 6G hydrazide with 7-diethylamino-3-(1-hydroxy-3-oxobut-1-enyl)-2H-chromen-2-one. As a colourimetric and ratiometric fluorescent probe, the derivative exhibited high selectivity towards Cu2+ in neutral aqueous media. Moreover, the probe sensed Hg2+ with fluorescence enhancement at pH 10. The binding process was confirmed via UV-vis absorption, fluorescence measurements, 1H NMR, mass spectroscopy and density functional theory calculation. To validate the applicability of the probe, the probe was used to detect Cu2+ and Hg2+ ions in actual water samples. The application of the fluorescent sensor in monitoring intracellular Cu2+ in Hela cells has also been demonstrated.

Two bis(pyrrol-2-yl-methyleneamine) chemo-sensors, 1, 3- and 1, 4-bis[3,4-dimethyl-5-ethyloxy -carbonyl-pyrrol-2-yl-methyleneamine]benzene (H2L(1) and H2L(2), respectively) have been synthesized and characterized, which exhibit high selectivity as off-on fluorescence sensors toward Zn(2+) in CH3CN/H2O (9:1, v/v) solution. The detection limits of both sensors are at the parts per million level. Moreover, the probes H2L(1) and H2L(2) could sense Zn(2+) by "naked eye" with a color change from colorless to yellow, and from yellow to dark yellow, respectively. To test the practical use of the probes, the determination of Zn(2+) in real water samples was also evaluated.

An aggregation-induced emission (AIE)- and intramolecular charge transfer (ICT)-based probe 1 (7‑hydroxy‑3‑(3‑methyl‑isoxazol‑5‑yl)‑chromen‑2‑one) that is highly selective for N2H4 has been synthesized, exhibiting a ‘turn-on’ response toward N2H4 in CH3CN/H2O solution. The detection limit of the probe was 2.90 ppb, which was evidently lower than the threshold limit value (10 ppb) recommended by the Environmental Protection Agency. Notably, the sensor could be used for the detection of N2H4 in living cells.

A simple asymmetric hydrazone 1 based on salicylaldehyde was designed and prepared, and exhibited an evident aggregation-induced emission (AIE) at a long wavelength of 570 nm in aqueous medium. Probe 1 can selectively sense Al

A novel dicyanomethylene-4H-pyran-based sensor bearing 2-thiophenecarbonyl as a masking group was established for the detection of cyanide anions. Upon the addition of cyanide, sensor 1 manifested a near-infrared emission band at 717 nm, with an extremely large red-shift (~180 nm) in the absorption spectrum. It also showed an obvious color change from yellow to green. Sensor 1 was used to sensitively measure CN− with low detection limit of 1.44 μM. The stoichiometric ratio between probe and CN− were determined as 1:1, with the association constant of 7.87 × 102 M−1. The reaction mechanism was investigated by ESI-MS, 1H NMR, HPLC, and density functional theory methods. Results indicate that the nucleophilicity of the cyanide catalyzes the elimination of 2-thiophenecarbonyl, which strengthens the intramolecular charge transfer effect of the dicyanomethylene-4H-pyran fluorophore. Furthermore, sensor 1 was found to be efficient in detecting cyanide in the intracellular region of MCF-7 cells.

A new rhodamine-based derivative bearing pyrrole unit, R1 was synthesized as a dual-mode Cu2+-selective sensor via the rhodamine ring-opening approach and ratiometric displacement. A colorimetric and “off-on” signal for Cu2+ through rhodamine ring opening in R1 and ratiometric fluorescent signal output when Cu2+ displaces the bound Cd2+ in the R1-Cd2+ complex can be observed. The application of fluorescent R1 to biological imaging was also demonstrated.

A novel turn-off fluorescent probe bearing a benzoxazole fluorophore has been synthesised and characterised. Its recognition properties towards different metal ions have been researched by spectrometry. The probe was highly selective and sensitive to Hg2+ and showed a complexation ratio towards Hg2+ of 1:1. Its fluorescence intensity varied almost linearly with the concentration of Hg2+ (1.6~8.6 μmol L−1), and the detection limit of Hg2+ was estimated to be 0.68 μmol L−1.

A quinoline-based hydrazone, namely, bis((quinolin-8-yl)methylene)carbonohydrazide (1), has been designed and synthesized, which could be used as a dual probe for selective recognition of Co2+ and Zn2+ by monitoring changes in absorption and fluorescence spectral pattern, respectively. The detection limits of 1 for these two ions are 0.21 and 0.66 μM, respectively. The complex formation between 1 and Co2+/Zn2+ is responsible for the detection process, as confirmed through several spectral methods and DFT calculations. The application of the as-synthesized sensor is demonstrated in Zn2+ imaging in living cells.

A simple chemosensor, 6-(1H-pyrrol-2-yl)-5,6-dihydro-benzo[4,5]imidazo[1,2-c]quinazoline (1), was synthesized via simple nucleophilic addition reaction coupled with Schiff base condensation. The probe 1 is aggregation-induced emission-active and could be used as an on–off fluorescence sensor toward Cu2+ in H2O/CH3CN (99.5%, v/v) solution. Furthermore, the resultant Cu2+ complex selectively responded to pyrophosphate (PPi) among various anions based on fluorescent on–off signal. In addition, the probe could be used for detecting Cu2+ and PPi in HeLa cells.

Far-red to near-infrared (NIR) fluorescent probes with absorption and emission in the spectral region of 600–900 nm are of high interest because of their low autofluorescence interference, deep-tissue penetration, and minimal photodamage to biological samples. In recent years, the Si-substituted xanthenes have attracted considerable attention owing to their remarkable far-red to NIR photophysical properties and biocompatible characteristics. This paper reviews the synthetic methods of silicon-substituted xanthene dyes and the progress in the development of far-red to NIR fluorescent probes based on these dyes, and introduces representative chemosensors along with their fluorescent behavior toward specific analytes. The fluorescent probes in sensing various biological species, including metal ions and anions, intracellular pH changes, reactive oxygen species (ROS) and reactive nitrogen species (RNS), as well as enzymes and other related species, were summarized. The sensing mechanisms and applications of corresponding sensors are also discussed.

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.

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-N2H4 [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 3.2ppb. The sensing mechanism was supported by 1H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated.

Graphene nanomaterials are typically used in biosensing applications, and they have been demonstrated as good fluorescence quenchers. While many conventional amplification platforms are available, developing new nanomaterials and establishing simple, enzyme-free and low-cost strategies for high sensitivity biosensing is still challenging. Therefore, in this work, a core-shell magnetic graphitic nanocapsule (MGN) material is synthesized and its capabilities for the detection of biomolecules are investigated. MGN combines the unique properties of graphene and magnetic particles into one simple and sensitive biosensing platform, which quenches around 98% of the dye fluorescence within minutes. Based on a programmed multipurpose DNA capturing and releasing strategy, the MGN sensing platform demonstrates an outstanding capacity to fish, enrich, and detect DNA. Target DNA molecules as low as 50 pM could be detected, which is 3-fold lower than the limit of detection commonly achieved by carbon nanotube and graphene-based fluorescent biosensors. Moreover, the MGN platform exhibits good sensing specificity against DNA mismatch tests. Overall, therefore, these magnetic graphitic nanocapsules demonstrate a promising tool for molecular disease diagnosis and biomedicine. This simple fishing and enrichment strategy may also be extended to other biological and environmental applications and systems.

On the basis of the remarkable difference in affinity of graphene (GO) with ssDNA containing a different number of bases in length, we for the first time report a GO-DNAzyme based biosensor for amplified fluorescence "turn-on" detection of Pb(2+). A FAM-labeled DNAzyme-substrate hybrid acted as both a molecular recognition module and signal reporter and GO as a superquencher. By taking advantage of the super fluorescence quenching efficiency of GO, our proposed biosensor exhibits a high sensitivity toward the target with a detection limit of 300 pM for Pb(2+), which is lower than previously reported for catalytic beacons. Moreover, with the choice of a classic Pb(2+)-dependent GR-5 DNAzyme instead of 8-17 DNAzyme as the catalytic unit, the newly designed sensing system also shows an obviously improved selectivity than previously reported methods. Moreover, the sensing system was used for the determination of Pb(2+) in river water samples with satisfying results.

Two new binuclear complexes, Cd2(HL)2(NO3)4 · (CH3OH)2 (1) and Cu2(L)2(ClO4)2 (2), based on N′-(pyridin-2-ylmethylene)-2-(1H-1,2,4-triazol-1-yl)acetohydrazide (HL) and Cd(II) and Cu(II) salts have been synthesized and characterized by single crystal X-ray diffraction. Hydrogen bonds and π–π interactions extend both binuclear molecules, a 3-D supramolecular framework for 1 and 1-D staggered chains for 2. Fluorescence of both complexes is discussed.

Recent studies have demonstrated that lymphocytes play a key role in ischemic brain injury. However, there is still a lack of viable approaches to non-invasively track infiltrating lymphocytes and reveal their key spatiotemporal events in the inflamed central nervous system (CNS). Here we describe an in vivo imaging approach for sequential monitoring of brain-infiltrating CD4+ T cells in experimental ischemic stroke. We show that magnetic resonance imaging (MRI) or Xenogen imaging combined with labeling of SPIO-Molday ION Rhodamine-B (MIRB) can be used to monitor the dynamics of CD4+ T cells in a passive transfer model. MIRB-labeled CD4+ T cells can be longitudinally visualized in the mouse brain and peripheral organs such as the spleen and liver after cerebral ischemia. Immunostaining of tissue sections showed similar kinetics of MIRB-labeled CD4+ T cells when compared with in vivo observations. Our results demonstrated the use of MIRB coupled with in vivo imaging as a valid method to track CD4+ T cells in ischemic brain injury. This approach will facilitate future investigations to identify the dynamics and key spatiotemporal events for brain-infiltrating lymphocytes in CNS inflammatory diseases.

Three new aryl amide type ligands, N-(phenyl)-2-(quinolin-8-yloxy)acetamide (L(1)), N-(benzyl)-2-(quinolin-8-yloxy)acetamide (L(2)) and N-(naphthalene-1-yl)-2-(quinolin-8-yloxy)acetamide (L(3)) were synthesized. With these ligands, three series of lanthanide(III) complexes were prepared: [Ln(L(1))(2)(NO(3))(2)]NO(3), [Ln(L(2))(2)(NO(3))(2)(H(2)O)(2)]NO(3).H(2)O and [Ln(L(3))(2)(NO(3))(2)(H(2)O)(2)]NO(3).H(2)O (Ln=La, Sm, Eu, Gd). The complexes were characterized by the elemental analyses, molar conductivity, (1)H NMR spectra, IR spectra and TG-DTA. The fluorescence properties of complexes in the solid state and the triplet state energies of the ligands were studied in detail, respectively. It was found that the Eu(III) complexes have bright red fluorescence in solid state. The energies of excited triplet state for the three ligands are 20325 cm(-1) (L(3)), 21053 cm(-1) (L(2)) and 22831 cm(-1) (L(1)), respectively. All the three ligands sensitize Eu(III) strongly and the order of the emission intensity for the Eu(III) complexes with the three ligands is L(3)L(2)L(1). It can be explained by the relative energy gap between the lowest triplet energy level of the ligand (T) and (5)D(1) of Eu(III). This means that the triplet energy level of the ligand is the chief factor, which dominates Eu(III) complexes luminescence.