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A luminescent trimethylamine (TMA) sensor, PTMA-Ir, has been designed and synthesized through immobilizing a phosphorescent iridium(III) complex on a TMA-imprinted polymer. Detailed study shows that the quenching of phosphorescence of PTMA-Ir can serve as a reporter for the binding of TMA on the imprinting sites, thus providing a sensitive, selective, and rapid detection of TMA in both aqueous solutions and gaseous states. Loading PTMA-Ir on filter paper produced a deposition T-Ir, the phosphorescence of which is quenched within 5 s upon exposure to TMA vapor with detection limits of 9.0 ± 0.1 ppm under argon and 15.0 ± 0.1 ppm in an air atmosphere. This work provided an effective method for establishing an imprinting polymer-immobilized luminescent amine sensor. [ABSTRACT FROM AUTHOR]

Hypochlorite (ClO−) is closely involved in human health and environmental safety. Therefore, it is of vital importance to realize the detection and separation of ClO−. Herein, a nanoprobe with analysis and removal capabilities of ClO− was synthesized via immobilizing coumarin-based functional molecules on halloysite nanotubes. The probe can easily detect ClO− in aqueous solution without the need for organic solvents, showing a fast detection time (10 s), a wide pH range (4–11), a low detection limit (8.4 nM), and a credible recovery rate range of 93.6–105.1%. The probe was further prepared into convenient test papers to realize the visual detection of ClO−. More importantly, it also enabled the removal of ClO−, and the removal rate was as high as 99.6%. [ABSTRACT FROM AUTHOR]

A novel water-stable CdII-based metal–organic framework, namely {[Cd(BIBT)(TDC)]·2H2O}n (JXUST-28, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2TDC = 2,5-thiophenedicarboxylic acid), was synthesized using a mixed-ligand strategy. Structural analysis demonstrates that JXUST-28 exhibits a two-dimensional layer structure with 4-connected sql topology. Intriguingly, JXUST-28 presents good stability in boiling water (at least 5 days), common organic solvents and aqueous solutions with different pH values of 2–12 (more than 24 hours). Furthermore, fluorescence experiments revealed that JXUST-28 could sense Hg2+ ions in aqueous solution via a quenching effect with a detection limit of 0.097 μM. Meanwhile, JXUST-28 can also be regenerated at least 5 times to detect Hg2+ ions. In addition, light-emitting diode lamps, luminescent films, and test papers of JXUST-28 have been successfully developed for practical applications. [ABSTRACT FROM AUTHOR]

A new water-stable three-dimensional (3D) Eu(III) metal–organic framework with the formula of {[Eu3(BTDC)4(HCOO)(H2O)2]·solvents}n (JXUST-9) was successfully obtained by the solvothermal reaction of 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H2BTDC) and Eu(NO3)3·6H2O. The PXRD patterns indicate that JXUST-9 exhibits good stability when soaked in boiling water for at least 24 h. The fluorescence experiments indicate that JXUST-9 could be considered as a good multi-responsive sensing material for detecting Fe3+, MnO4− and Cr2O72− in aqueous solutions via the turn-off effect, and the detection limits are 0.94 μM, 1.23 μM and 1.23 μM, respectively. JXUST-9 can also be regenerated at least five times for sensing Fe3+, MnO4− and Cr2O72−. Moreover, a rapid detection test paper incorporated with JXUST-9 has been produced, which is helpful for carrying out visual detection of Fe3+, MnO4− and Cr2O72− in daily applications. [ABSTRACT FROM AUTHOR]

Rare earth elements are greatly valued for their crucial role in many high-tech fields. Highly sensitive and precise determination technology of these elements in aqueous solution is essential for the extraction and recycling processes of these elements. Currently, conventional measurement methods for rare earth elements, such as ICP-MS and ICP-OES, often suffer from issues related to complex operations, lengthy procedures, and low economic efficiency. While laser-induced breakdown spectroscopy (LIBS) provides fast and convenient detection capability, due to the matrix effect of the water LIBS technology itself, the reported sensitivities of these elements have not met the application requirements for detection capabilities. In this work, we propose a method that utilizes a micro-hole array sprayer to rapidly prepare rare earth aqueous solution samples into densely and uniformly adhered particles on an Al substrate, combined with a computer-controlled three-dimensional displacement platform to facilitate fully automated LIBS detection. Through optimization of system parameters, the detection limits for La, Pr, Nd, and Sm reach 8.6, 22.3, 13.6, and 6 μg L−1, respectively, with a stable repeatability of 4.96%, within a total sample preparation and detection time of no more than 15 minutes. Compared to existing LIBS-based detection methods, the average detection limits have been reduced by two orders of magnitude, essentially meeting the ppb-level requirements for practical production. This demonstrates the potential of our system to develop into a fast, low-cost, standardized detection technology in the field of rare earth element exploration, mining, and recovery. [ABSTRACT FROM AUTHOR]

It is highly desirable to detect malononitrile in organisms and human bodies owning to its inherent toxicity. With dicyanovinyl as the recognition site, a Michael addition reaction-based fluorescent probe Hcy-DCV was developed for malononitrile detection. A notable advantage of this probe is that it responds quickly to malononitrile without any additive to speed the sensing reaction. It has a good water solubility and the detection limit was determined to be 6.92 ppb in 100% aqueous solution. In particular, Hcy-DCV exhibited good selectivity towards malononitrile over other interfering substances including hydrazine and other active methylene compounds. The probe was applied successfully to quantitate malononitrile in pure water with satisfying recovery and relative standard deviation. Additionally, the ability of visualizing malononitrile by using probe-coated strip papers was displayed, which may facilitate the on-site detection of malononitrile. Moreover, the bioimaging of malononitrile in living H1975 cells and zebrafish larvae was also demonstrated. All the experimental results suggested the potential of Hcy-DCV for practical detection of malononitrile in both environmental and biological samples. [ABSTRACT FROM AUTHOR]

Tracing toxic cyanide (CN−) in water and cyanogenic food samples is a demanding task for the research community. However, the poor solubility of organic probes in aqueous media often becomes a huge hurdle for in-field application. Herein, a novel colorimetric water-soluble polymeric probe, p(N,N′-dimethylacrylamide-co-azo-dicyano) (p(DMA-co-azo-dicyano)), P1, was created and synthesized for the purpose of detecting CN− in 100% water. Specifically, P1 was synthesized via post-polymerization modification of (p(DMA-co-azo-aldehyde)) with malononitrile. P1 demonstrated selective sensing behaviour toward CN− in water at physiological pH using intramolecular charge transfer (ICT) as a mechanism. Upon the inclusion of CN−, the color of P1 changed from red to yellow (a ∼57 nm blue shift) with the lower limit of detection (LOD) of 0.008 mM. Additionally, P1-coated test strips were used for "in-the-field" measurements for CN− detection in aqueous solution and cyanogenic food samples. [ABSTRACT FROM AUTHOR]

A TPA-ME fluorescent probe, based on triphenylamine derivative TPA-CHO, has been designed, synthesized and characterized by different spectroscopic methods successfully. TPA-ME and TPA-CHO present similar aggregation-induced emission (AIE) effects under same conditions. Due to the deprotection reaction of mercaptal promoted by mercury ions (Hg2+), TPA-ME exhibits excellent selectivity and anti-inference properties over other tested ions in the DMF/H2O (fw 70%, pH 6.8) medium. Upon increasing Hg2+, the fluorescence of the TPA-ME probe shows an obvious red-shift from blue to green. The fluorescence intensity has a good linearity toward Hg2+, with the limit of detection (LOD) below 1.23 × 10−7 mol L−1. A theoretical calculation was carried out to understand the difference between TPA-ME and TPA-CHO, and experimental results have been met with simulation calculations. Along with the result of the fluorescence change, Hg2+ can be easily tested through a conveniently prepared test paper. [ABSTRACT FROM AUTHOR]

The use of ion-selective electrodes (ISE) is a well-established technique for the detection of ions in aqueous solutions but requires the use of a reference electrode. Here, we introduce a platform of ion-selective chemiresistors for the detection of nitrogen species in water as an alternative method without the need for reference electrodes. Chemiresistors have a sensitive surface that is prone to damage during operation in aqueous solutions. By applying a layer of ion-selective membrane to the surface of the chemiresistive device, the surface becomes protected and highly selective. We demonstrate both anion-selective (NO3−, NO2−) and cation-selective (NH4+) membranes. The nitrate sensors are able to measure nitrate ions in a range of 2.2–220 ppm with a detection limit of 0.3 ppm. The nitrite sensors respond between 67 ppb and 67 ppm of nitrite ions (64 ppb detection limit). The ammonium sensors can measure ammonium concentrations in a wide range from 10 ppb to 100 ppm (0.5 ppb detection limit). The fast responses to nitrate and nitrite are due to a mechanism involving electrostatic gating repulsion between negative charge carriers of the film and anions while ammonium detection arises from two mechanisms based on electrostatic gating repulsion and adsorption of ammonium ions at the surface of the p-doped chemiresistive film. The adsorption phenomenon slows down the recovery time of the ammonium sensor. This sensor design is a new platform to continuously monitor ions in industrial, domestic, and environmental water resources by robust chemiresistive devices. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are a unique class of multifunctional hybrid crystals that have been successfully utilized in diverse ranges of applications. However, since MOFs are prone to aqueous degradation, the development of stable luminescent MOF platforms in aqueous media is still a huge challenge. Here, a novel dual-ligand Eu3+/DUT-52-COOH composite is prepared based on the luminescent DUT-52 prototype structure via a dual-ligand strategy and a post-synthetic modification (PSM) method. The functionalized Eu3+/DUT-52-COOH material exhibits dual emission and good photothermal stability in aqueous media. Thus, Eu3+/DUT-52-COOH is developed as a ratiometric luminescent sensor to achieve highly selective and sensitive detection of Cu2+ and Cr2O72− in aqueous solutions and has a low detection limit of 3.43 μM and 25.7 nM, respectively. This work is one of the few cases of detecting Cu2+ and Cr2O72− in aqueous media based on a DUT-52, and the detection signals can be observed by the bare eye without using sophisticated analytical instruments. The possible sensing mechanism is discussed in detail. The results obtained in this project may provide broad prospects for developing smart sensing systems to accomplish highly efficient, easily operable and quantitative intelligent recognition of Cu2+ and Cr2O72−. [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HOCl) is crucial in various physiological processes, and monitoring its level in organisms is essential for understanding its biological functions and pathological effects. In this study, we developed a novel fluorescent probe based on dicyclohexylphosphine for rapid and sensitive detection of HOCl in an aqueous solution. The probe exhibits a significant fluorescence turn-on response to HOCl through the specific oxidative reaction between dicyclohexylphosphine and HOCl. It possesses high selectivity, instantaneous response (approximately 1 s), and a low detection limit of 15.3 nM. Moreover, biological imaging results demonstrated that the probe could be used for real-time fluorescence imaging of HOCl in living cells and zebrafish. The development of this probe may provide new insights into designing phosphine-based fluorescent probes for detecting oxidative species. [ABSTRACT FROM AUTHOR]

In recent years, antibiotic pollution has become a major concern due to their excessive exposure to humans and the environment. However, the existing instrument-dependent and time-consuming conventional detection approaches are not feasible for the real-time detection of antibiotics at the field level. Herein, two Cu-based metal–organic frameworks (Cu-btc) with the same stoichiometry were synthesized under different reaction conditions. The hydrothermal approach resulted in better structural and crystalline properties of Cu-btc (named as Cu-MOF2) than the preparation under normal laboratory conditions (Cu-MOF1). The high peroxidase-like activity of Cu-MOF2 was further utilized to develop a colorimetric assay for the detection of tetracycline in water. The presence of multiple O- and N-functional groups in tetracycline led the formation of tetracycline–Cu2+ complexes. Tetracycline itself did not cause any change in the color of the TMB-H2O2 system, but it could effectively hinder the colorimetric reaction of TMB with H2O2 in the presence of Cu-MOF2. The designed system demonstrated a low detection limit of 0.23 μM with a limit of quantification of 0.69 μM. The performance of this colorimetric assay was also examined in the presence of other possible interfering antibiotics. The good biocompatibility of this sensing platform increases its potential for in vitro biosensing applications. [ABSTRACT FROM AUTHOR]

A CdII-based coordination polymer with the formula [Cd(BIBT)(3,4-TDC)]n (JXUST-27, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and 3,4-H2TDC = thiophene-3,4-dicarboxylic acid) was synthesized under solvothermal conditions. Single-crystal structural determination reveals that JXUST-27 adopts a two-dimensional structure with sql topology. JXUST-27 can keep stable up to 317 °C and in common solvents. In particular, JXUST-27 exhibits excellent stability when the samples are immersed in aqueous solutions with pH values of 2–13 or in boiling water for 24 hours. Furthermore, JXUST-27 could selectively detect salicylaldehyde (SA) through turn-off effect with a detection limit of 0.087 μM. More importantly, JXUST-27 represents the first CdII coordination polymer based fluorescence sensor toward SA in aqueous solution. In addition, the portable fluorescent film and light-emitting diode lamp based on JXUST-27 were further developed for the detection of SA. [ABSTRACT FROM AUTHOR]

Two structurally similar columnar ZnII-MOFs {[Zn8L4(TZ)4·0.5H2O]·4[Me2NH2]·6DMF·4H2O}n (Zn-MOF1) and {[Zn4L2(MT)2·H2O]·2[Me2NH2]·4DMF·4H2O}n (Zn-MOF2) were synthesized with irregular ligands, 2,2′-(pyridine-2,6-diyl) diterephthalic acid (H4L), 1,2,4-triazolium (TZ) and 1H-1,2,4-triazole-3-thiol (MT). Structural studies showed that both ZnII-MOFs had a similar 3D framework constructed with multiple SBUs and displayed an unusual (3,4,6)-connection topology. Furthermore, both ZnII-MOFs have high performance in gas adsorption and separation. The separation ratios of C2H2/CH4 and CO2/CH4 of Zn-MOF1 were 15.1 and 6.8, respectively, and those of Zn-MOF2 were 14.6 and 6.5, respectively. Moreover, Eu@Zn-MOF1 and Eu@Zn-MOF2 were successfully obtained by adding Eu3+ ions to the synthesis system. After a series of fluorescence tests, these two MOFs were found to have good fluorescence performance, and showed high selectivity and sensitivity to Fe3+ ions in aqueous solution with a low detection limit. [ABSTRACT FROM AUTHOR]

The hexaarylbenzene (HAB)-based push–pull fluorophore HAB-MeO-TPy with the 2,2′:6′,2″-terpyridine (TPy) unit as an acceptor and the methoxy (MeO) group as a donor was developed. It was observed that HAB-MeO-TPy exhibited an unusual uphill-type emission with increasing solvent polarity from cyclohexane to DMSO. By comparison with a previously reported fluorophore HPB-MeO-DCV, a structure–property relationship regarding this uncommon fluorescence behavior was disclosed. Furthermore, the sensing properties of HAB-MeO-TPy for metal ions were also investigated. In the presence of Fe2+, HAB-MeO-TPy displayed a visual color change from colorless to magenta, indicating that HAB-MeO-TPy can act as a "naked eye" sensor for Fe2+ detection. From absorption titration experiments, the detection limit was determined to be 1.50 × 10−7 M. In addition, HAB-MeO-TPy was successfully applied to detect Fe2+ in real water samples. [ABSTRACT FROM AUTHOR]

The search for feasible and efficient methods for sensing cations in the environment is a challenge of current scientific interest. Among the colorimetric and fluorometric methods, those that enable the direct and rapid detection of the analytes are highly desirable. Here a simple approach based on the transmetalation of a Zn(II) Schiff-base complex for the selective and sensitive colorimetric and fluorometric detection of Cu2+ ions in aqueous solution is reported. This method offers the advantages of being direct, fast, and not requiring any treatment of the sample. A detection limit down to 0.60 μM is obtained from the spectrophotometric data. The method is demonstrated to be efficient for the quantitation of Cu2+ ions in drinking water. [ABSTRACT FROM AUTHOR]

Five novel isostructural two-dimensional lanthanide complexes [Ln2(μ3-L)2(μ4-L)(H2O)3]n·nH2O, (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5); H2L = 5-(pyridin-3-yloxy)isophthalic acid) have been hydrothermally synthesized. They are characterized by IR spectroscopy, X-ray diffraction and thermogravimetric analyses. Complexes 1–5 crystallize in the monoclinic space group P21/c and display a 2D layered structure. They have good thermal stability, and the skeleton structure can be maintained up to 500 °C. The solid-state fluorescence of complexes 1 and 3 shows the strong characteristic red luminescence of Eu(III) and the green luminescence of Tb(III) respectively, and they exhibit a fluorescence quenching effect on addition of acetone in aqueous solution. The detection limits are 3.59 × 10−4 M and 2.08 × 10−6 M, respectively. Moreover, complex 3 also exhibits fluorescence quenching effects on Fe3+ and CrO2− in aqueous solution with detection limits of 4.81 × 10−8 M and 4.06 × 10−8 M, respectively, which are lower than those of most reported complexes. Therefore, complex 3 is a multifunctional visual fluorescent probe in aqueous solution. [ABSTRACT FROM AUTHOR]

Mercury(II) is one of the most toxic ions and has the lowest allowed concentration in water. Lowering the detection limits of Hg2+ based on fluorescence methods is challenging compared to the detection of other heavy metal ions. Co-precipitation of the CsPbBr3 precursor and mercury ions in aqueous solutions was developed for the ultra-trace level detection of Hg2+. It was found that the formed CsPbBr3 crystals with sizes in the range of nanometers to micrometers exhibited strong fluorescence in the solid state free of water, and the incorporation of Hg2+ in the crystals would cause fluorescence quenching. Therefore, the decrease in fluorescence intensity could be used to quantitatively detect Hg2+. A microwell array was designed by dispersing the sample solution with the perovskite probe and evaporating water for 3 min to form solid fluorescent crystals, leading to the incorporation of Hg2+ in the crystals. This evaporation-induced co-precipitation strategy successfully solved the problem of the instability of perovskite materials in water. The concentration of Hg2+ can be obtained according to the decrease in the fluorescence intensity, which is caused by the replacement of Pb2+ by Hg2+ in the crystals during the crystallization process. The CsPbBr3 crystallites can be used to detect ultra-trace levels of Hg2+ simply and quickly, with a linear range of 5–100 nM and limit of detection (LOD) as low as 0.1 nM. More importantly, no organic molecules are required to prepare crystals since the micron-sized crystals have obvious fluorescence. This method demonstrates great promise in detecting low concentrations of Hg2+ in aqueous solutions. [ABSTRACT FROM AUTHOR]

In this manuscript, we present a chemosensor, 4-methyl-2,6-bis-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol (Hmpye), for selective detection of Zn2+ and Co2+ in 100% aqueous medium. The active component of the sensor is the Schiff base condensation product between 4-methyl-2,6-diformylphenol and 2,2-pyridyl ethylamine and the resultant moiety is ESIPT (excited-state intramolecular proton transfer) active via imine nitrogen and phenolic OH. The absorption and emission spectral investigations have been carried out extensively for the sensing system which showed that Hmpye is able to sense Zn2+ by fluorescence turn-on and Co2+ by fluorescence turn-off. Apart from Job's plot and ESI-MS studies, the single crystal X-ray diffraction study has been utilized to ascertain the 1 : 2 ratio of the sensor : Zn2+ ensemble. The detection limits for Zn2+ and Co2+ are 4.683 × 10−9 (M) and 7.591 × 10−9 (M), respectively. The sensing capability of Hmpye has also been checked in HCT live cells. The potential of the work has been demonstrated by the fact that nanomolar detection of Zn2+ and Co2+ from 100% aqueous solution can be achieved by a single probe which is scarce in the literature. [ABSTRACT FROM AUTHOR]

An inorganic--organic chemosensing material (MS-NSP) was developed by anchoring the bis-Schiff base fluorophore onto the channel surface of a SBA-15 mesoporous silica surface with a quaternary ammonium linker. The mesostructure, morphology, and spectral features of MS-NSP were systematically described. The nanohybrid could be implemented as a multifunctional fluorescent nanosensor for Cu2+ ions. A good linearity was observed over the concentration range from 0 to 4 mM, and the lower Cu2+ detection limit by MS-NSP was found to be 0.19 μM. Additionally, the fluorescence response of MS-NSP was remarkably specific for Cu2+ ions compared to other competitive ionic species. Moreover, the MS-NSP can also be utilized as an adsorbent for the effective elimination of Cu2+ from an aqueous solution. The kinetic features of adsorption were well described by the pseudo-second-order model and the sorption isotherm was in agreement with the Langmuir model. The theoretical maximum adsorption amount of Cu2+ ions was determined at 58.5 mg g-1. Finally, the interaction of MS-NSP and Cu2+ was investigated using theoretical calculations. Overall, the material in the present study is useful for both the sensitive detection and effective extraction of Cu2+ ions. [ABSTRACT FROM AUTHOR]

One-pot synthesis of Mn3O4 nanorods is reported for the first time by the oxidation of manganese metal resulting from reducing Mn2+ by NaBH4 at room temperature. The resultant Mn3O4 nanorods were 10–70 nm in width and up to hundreds of nanometers in length, and were very stable in aqueous solution. The Mn3O4 nanorods can oxidize H2O2 under acidic conditions quickly accompanying their decomposition. Using 3,3′,5,5′-tetramethylbenzidine (TMB) as a competitive chromogenic substance, colorimetric methods were developed for the sensitive detection of H2O2 and glucose. The methods exhibited a linear range of 2–100 μM with a limit of detection (LOD) of 1.7 μM for detecting H2O2, and a linear range of 5–200 μM with a LOD of 4.4 μM for detecting glucose. The application in analyzing glucose in human serum samples demonstrates its practicability. [ABSTRACT FROM AUTHOR]

We have prepared a type of magnetic mesoporous nanomaterial with aggregation-induced emission properties (Fe3O4@mSiO2@TPA@BA, hence abbr. FSTB) to detect and remove cyanide ions (CN−) under magnetic conditions. FSTB has a large specific surface area and improved fluorescence performance to identify CN−, and its superparamagnetic behavior plays an important role in removing CN−. The magnetic sensor FSTB shows excellent selectivity and anti-interference for the detection of CN− in aqueous solutions. It is obvious from the equation LOD = 3δ/S that the limit of detection (LOD) of FSTB for CN− is significantly lower than the permissible level of CN− in drinkable water recommended by the World Health Organization. Therefore, the magnetic sensor FSTB has a wide range of applications for detecting and removing harmful CN−. [ABSTRACT FROM AUTHOR]

As the environmental residues of formaldehyde and hypochlorites are very harmful to human health, a new simple and efficient aggregation-induced emission probe based on diaminomaleonitrile was designed and applied in the independent detection of hypochlorites and formaldehyde. The probe shows high selectivity and anti-interference ability against other potential competitive substances. ClO− promotes the oxidized splitting of C＝N in the probe, and induces evident color changes visible to the naked eye together with quenched fluorescence. The detection of ClO− by this probe was fast, sensitive, and visible to the naked eye. The detection limit of the probe to ClO− in the range of 0.70–20 μM is 18 nM. Through the condensation mechanism and with amine as the binding site of formaldehyde, the exposed amino group in the probe structure responds sensitively and efficiently to formaldehyde. The probe can effectively monitor 0.50–25 μM formaldehyde in aqueous solutions, with a detection limit as low as 42 nM. A portable solid sensor – a formaldehyde detection plate was built by directly covering the probe on a thin-layer chromatography plate. Thereby, formaldehyde gas can be effectively and sensitively detected, which offers a clue for developing solid-state formaldehyde-detection plates. The high experimental recovery rates prove that this new probe is highly promising in hypochlorite detection in the real water environment. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe CuNI was synthesized and exhibited highly effective fluorescence detection ability for Cu2+ in aqueous solution (HOAc–NaOAc buffer, 10 mM, pH 5.0). CuNI was obtained by a simple condensation reaction between the aldehyde (MFNI, bearing the naphthalimide fluorescence group) and the 2-picolinyl hydrazide, which bears the Cu2+ recognized group. Under acidic conditions, CuNI showed turn-on fluorescence recognition of Cu2+ which could be readily distinguished with the naked eye under a 365 nm UV lamp and the detection limit is as low as 19.40 nM. It has been further demonstrated that CuNI was hydrolyzed under the action of Cu2+ and the significant increase of fluorescence is due to the obvious AIE effect of the hydrolysate MFNI. The application of the probe CuNI in imaging lysosomal Cu2+ in HepG2 cells has also been demonstrated. [ABSTRACT FROM AUTHOR]

A multifunctional sensing platform based on bright blue-fluorescent nitrogen-doped carbon dots (N-CDs) has been ingeniously designed for the sensitive determination of Hg2+ and pH. The N-CDs were facilely fabricated via a one-step hydrothermal treatment of citric acid and folic acid with admirable merits including exceptional stability, low toxicity and distinguished biocompatibility. Intriguingly, the obtained N-CDs can be utilized to detect Hg2+ on the basis of the dynamic quenching effect, showing a linear range of 0 μM–400 μM as well as a detection limit of 0.124 μM. In addition, the obtained N-CDs revealed a significant emission enhancement with increasing pH from 4.0 to 10.0 and acquired a good linearity in the pH range of 6.8–7.8. Taking advantage of efficient analysis of Hg2+ and pH in aqueous solution, the as-synthesized N-CDs have been extended to the visualization biosensing platform to timely track Hg2+ and pH in living cells. [ABSTRACT FROM AUTHOR]

The first polyhydroxycarboxylic acid ligand bridged multi-EuIII-incorporated tellurotungstate K14H10[Eu4(H2O)4W6(H2glu)4O12(B-α-TeW9O33)4]·60H2O (H6glu = D -gluconic acid) (1) was synthesized via an organic ligand-driven self-assembly strategy. The polyhydroxycarboxylic acid ligand bridged tetrameric polyoxoanion [Eu4(H2O)4W6(H2glu)4O12(B-α-TeW9O33)4]24− in 1 can be viewed as an aggregation of four trivacant Keggin [B-α-TeW9O33]8− fragments and an innovative heterometallic [Eu4(H2O)4W6(H2glu)4O12]8+ cluster, in which four high-coordinate polyhydroxy flexible H2glu4− ligands chelate W and Eu centers through carboxyl and hydroxyl groups, giving rise to a heterometallic cluster. The hexagonal packing of the tetrameric polyoxoanions in 1 along the c axis provides excellent porous channels, which greatly increases the specific surface area of the whole framework and may be of benefit for fluorescence sensing in aqueous solution. 1 can function as a "turn-off" luminescence sensor to detect Cu2+ ions in aqueous solution. The limit of detection (LOD) of the 1-sensor is 8.82 × 10−6 mM, which is the lowest among the reported polyoxometalate-based fluorescence sensors. As for the Cu2+-quenching system, it can function as an "off–on" sensor to detect cysteine in an aqueous system, affording a LOD of 1.75 × 10−4 mM. This work opens up an avenue to broaden the applications of polyoxometalate-based materials in the optical intelligence detection field. [ABSTRACT FROM AUTHOR]

Furan Schiff base functionalized PEG (PEGFB) was synthesized as an excellent reversible fluorescent chemosensor for the sensitive detection of Al3+ in 100% aqueous solution. The non-fluorescent PEGFB displayed high selectivity towards Al3+ over other coexistent metal ions, accompanied by a visual fluorescence change from colorless to bright cyan. The detection limit of PEGFB towards Al3+ was determined to be 7.90 × 10−9 M. PEGFB could be utilized to detect Al3+ in a relatively wide pH range from 5 to 9. The reversible fluorescence response of PEGFB upon the addition of Al3+ and EDTA was successfully used to construct an INHIBIT molecular logic gate. Furthermore, test strips coated with PEGFB could be applied for the convenient and visual sensing of Al3+ in real water samples. [ABSTRACT FROM AUTHOR]

Detecting trace amounts of copper ions (Cu2+) is of high importance since copper is an essential element in the environment and the human body. Despite the recent advances in Cu2+ detection, the current approaches still suffer from insensitivity and lack of in situ detection in living cells. In the present work, a fluorescent nanosensor based on porphyrinic metal–organic framework nanoparticles (MOF-525 NPs) is proposed for sensitive and selective monitoring of Cu2+ in aqueous solution and living cells. The MOF-525 NPs with attractive properties, including ultrasmall size, good water dispersity and intense red fluorescence, are prepared via a facile and environment-friendly hydrothermal route. The fluorescence signal of MOF-525 NPs could be quenched statically by Cu2+ with high selectivity due to the strong affinity of Cu2+ to the porphyrin ligand in MOF-525. The proposed fluorescent nanosensor has a linear response in the range of 1.0–250 nM with a low detection limit of 220 pM. Furthermore, it is successfully employed for the detection of Cu2+ in water samples and the intracellular imaging of Cu2+ in living cells, demonstrating its great potential in the sensing and biological fields. [ABSTRACT FROM AUTHOR]

In this work, a sensing nanochannel based on a N-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole (DHI) modified nanopipette was prepared and characterized for the ultrasensitive detection of cobalt ions (Co2+) in aqueous solutions. By both experimental and theoretical studies, the detection conditions (chelation balance time, pH of the electrolyte, nanopipette diameter, potentials for ionic current) and parameters (rectification value, resistance and ionic current) have been fully optimized, and the proposed Co2+ sensor shows a significantly wide detection range from 20 fM to 0.2 mM, with an ultra-low detection limit down to 0.94 fM. [ABSTRACT FROM AUTHOR]

In the present work, we propose a new salicylaldehyde azine based water-soluble fluorescent sensor (PSSA – 4-propoxysulfonate salicylaldehyde azine) dedicated to aluminium(III) detection in aqueous solutions. The introduction of sulfonate functional groups provides the probe with enhanced water-solubility, which is crucial for the direct analysis of polluted samples. We proved that aluminium(III) complexation with PSSA in water induces an aggregation-induced emission enhancement (AIEE) process leading to the formation of well-defined dendritic structures which have been characterized by different analysis techniques (DLS, SEM, and FLIM). A limit of detection towards aluminium(III) of 153 nM has been determined, which is more than one order of magnitude below the World Health Organization (WHO) guideline (≈3.7 μM). Moreover, satisfactory selectivity for this compound has been demonstrated over a large variety of metal cations. Finally, PSSA has been introduced into a digital microfluidic sensor chip, thus providing a sub-micromolar portable detection device devoted to aluminium(III) polluted water samples. [ABSTRACT FROM AUTHOR]

Herein, several boronic acid-based sensors were reported selectively recognizing D -sorbitol in aqueous solution. The fluorescence of sensor 15c was enhanced by 1.5-fold when combined with a low concentration of D -sorbitol (8.88 μM), and the fluorescence enhanced by 0.6-fold after binding to D -fructose, while it did not change obviously when combined with other carbohydrates, including D -arabinose, D -galactose, D -mannose, D -ribose, D -maltose, D -xylose, D -glucose and D -glucosamine. Fluorescence tests were carried out in DMSO/PBS (pH 9, 0.1 M) solution (1 : 99, v/v), at room temperature, which indicated that the sensors are water-soluble. In addition, competition studies showed that sensor 15c works well as a D -sorbitol-specific fluorescence sensor in both the absence and presence of carbohydrate interferents. And sensor 15c has a high binding constant (10 922 ± 776 M−1) and a low limit of detection (6.91 × 10−7 M) at pH 9 among the investigated sensors toward D -sorbitol. Furthermore, sensor 15c was applied to the analysis of real samples (D -sorbitol for oral administration). These studies indicated that sensor 15c may serve as a potential tool to detect the content of D -sorbitol in drugs and food products. [ABSTRACT FROM AUTHOR]

Ion-imprinted polymer-decorated SBA-15 (SBA-15-IIP) for the adsorption of copper was synthesized and characterized using different techniques, including FT-IR, XRD, TG/DTA, SEM, BET, and TEM. It was used as a green, efficient and rapid sorbent for the removal of Cu(ii) from aqueous solution. The effect of several parameters on the removal percentage of copper was studied using the central composite design. The equilibrium data were investigated using the Langmuir and Freundlich isotherm models, and found to be well-fitted by the Langmuir model with the maximum adsorption capacity of 322.58 mg g−1. The adsorption kinetics was investigated using four models, and found to be well-fitted by the pseudo-second-order model. Also, the recyclability of SBA-15-IIP was studied, and the results after 6 cycles demonstrated that SBA-15-IIP was a promising sorbent for the removal of Cu(ii) from aqueous solution. Subsequently, SBA-15-IIP was used as an efficient and selective sorbent for the extraction of Cu(ii). Various parameters affecting the extraction efficiency of the analyte were investigated and optimized using the Box–Behnken design. The optimized methodology presented good linearity between 0.2 and 100 μg L−1 (R2 ＞ 0.9946) and a detection limit of 0.05 μg L−1. The method had an enhancement factor of 220 and relative standard deviation (RSD) of 3.1% and 4.5% for intra-day and inter-day, respectively. [ABSTRACT FROM AUTHOR]

Semiconductor-based materials as SERS-active substrates have gained significant attention because of their superior properties. However, to date, only few studies have been reported on the SERS performance of substrates fabricated using CdS-based composites. In this study, hollow sphere-like Ag/CdS nanocomposites (NCs) with multi-hot spots were successfully synthesized via a room-temperature solution route without the addition of surfactant. Especially, note that in our strategy, the cadmium ions in an aqueous solution originating from the self-template core dissolved with acid were retrieved and recycled via a simple approach, avoiding the wastage of resources and environmental problems. Moreover, a strong electromagnetic enhancement between two neighboring Ag nanoparticles (NPs) on the CdS sphere-like surface could be achieved by conveniently adjusting the amount of the AgNO3 reagent. Note that the as-prepared substrate with low loading of Ag presented superior SERS performance with the ultralow limit of detection of 10−12 mol L−1 for R6G and CV, much higher than that of many recently reported composite substrates. These significantly enhanced SERS effects are attributed to the combination of several contributions, including plasmonic coupling between Ag NPs, synergistic charge-transfer resonances in the Ag/CdS/dye molecule system, and cadmium defect-induced electrostatic forces. As a consequence, the present study not only develops a convenient, environmentally friendly approach for the fabrication of noble/CdS composites but also indicates the promising potential application of these composites as ideal SERS substrates in the detection of organic pollutants. [ABSTRACT FROM AUTHOR]

A water-soluble fluorescent probe for monitoring thiophenols based on a GFP-type TPC-OH fluorophore and a 2,4-dinitrophenyl ether recognition unit was designed. This probe possessed remarkable sensitivity and specificity toward thiophenols in an almost pure aqueous solution, and also showed good interference immunity to other related analytes including aliphatic mercaptans. Meanwhile, the probe displayed a prominent linear correlation between the thiophenol concentrations in the range of 0 to 20 μM and the fluorescence intensities at 492 nm, and the detection limit was as low as 33 nM. More strikingly, probe 1 was employed to visualize thiophenol in both living cells and zebrafish, which further demonstrated that probe 1 was a powerful practical tool in monitoring thiophenols in living systems. [ABSTRACT FROM AUTHOR]

The development of selective and sensitive complex molecular systems for the detection of Ag+ ions is of great importance because the extensive use of the toxic silver containing materials has adverse effects on the human health and the environment. Here, we report a new chemosensor for silver ion recognition in aqueous solutions, which was constructed by integrating three moieties: silatrane, 1,2,3-triazole and barbituric acid, using Knoevenagel condensation and Cu(i) catalyzed [2+3] azide–alkyne cycloaddition reaction. The sensing assay based on silatrane exhibited high selectivity and high specificity towards silver ions. Overall, the results show that this strategy to develop new functional materials can be employed for the efficient sensing of Ag+ ions. Further, the benefit of the existence of silicon in the receptor lies in the extension of this molecular system in the field of nanochemistry, where silica-based nanomaterials can have more significant outcomes. Moreover, the ion detection ability in aqueous solution makes the sensor suitable to be employed for detection in real samples. [ABSTRACT FROM AUTHOR]

Triphenylene derivative 4 bearing gallic acid groups at the periphery has been synthesized. Derivative 4 formed “not quenched” porous aggregates in mixed aqueous medium. These aggregates served as potent chemosensors for the selective detection of trinitrotoluene (TNT) in mixed aqueous media and the detection limit in the range of 228.6 × 10−12 g L−1 (228.6 parts per quadrillion) was observed. Interestingly, due to the porous morphology of these aggregates of derivative 4, they could detect TNT in the vapor phase also. In addition, the dip strips coated by the aggregates of derivative 4 could detect TNT in contact mode with detection limits of 22.7 attograms cm−2. [ABSTRACT FROM AUTHOR]

A new highly selective colorimetric chemosensor 1 (E)-9-(((5-mercapto-1,3,4-thiadiazol-2-yl)imino)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol was designed and synthesized for the sequential detection of Cu2+ and CN−. This sensor 1 exhibited an obvious color change from yellow to orange in the presence of Cu2+ in a fully aqueous solution. The detection limit (0.9 μM) of 1 for Cu2+ is far lower than the WHO limit (31.5 μM) for drinking water. In addition, the resulting Cu2+-2·1 complex can be further used to detect toxic cyanide through a color change from orange to yellow, indicating the recovery of 1 from Cu2+-2·1. Importantly, chemosensor 1 could be used to detect and quantify Cu2+ in water samples, and a colorimetric test strip of 1 for the detection of Cu2+ could be useful for all practical purposes. [ABSTRACT FROM AUTHOR]

A TPE-based fluorescent porous covalent organic polymer (COP-3) was designed and synthesized. The COP-3 exhibits excellent performance in sensing Fe3+ with high anti-interference, recyclability and a low limit of detection (LOD) of 0.191 μM (10.696 ppb), which is much lower than those of the reported metal-free porous polymers. [ABSTRACT FROM AUTHOR]

We report two isostructural dinuclear transition metal complexes [M2(HL)2(N3)4], where M = Ni2+ (BS-1), Mn2+ (BS-2), and HL is (2-methyl-2-((pyridin-2-ylmethyl)amino)propan-1-ol) and investigate them as molecular sensors towards hazardous entities. BS-1 shows high selectivity towards the S2− and Ag+ ions, easily observed by the naked eye colour change and its detection limit in aqueous solutions for the S2− ion was calculated as 0.55 μM with a binding constant of 3.28 × 105 M−1, while the limit for the Ag+ ion is 21.8 μM. Notably, BS-2 shows good selectivity towards the Ag+ ion with a detection limit of 10.84 μM. Spectroscopic and DFT studies shed light on the mechanistic course of interaction between the host and guest entities, suggesting a sulphide-mediated reduction of the azide mechanism. In a nutshell, these simple transition metal complexes were exploited for discriminately detecting hazardous analytes with real field applications in analytical science (via. "Dip-Stick" approach) as well as engineering science, which provides a significant contribution in the recent advancement of supramolecular chemistry. [ABSTRACT FROM AUTHOR]

A “turn on” fluorescent and colorimetric sensor, HAT(CN)6, was developed for the light-up detection of cyanide. It was implemented through its strong anion–π interaction, inducing thermal CN−→ HAT(CN)6 electron transfer, to give the dianion product [HAT(CN)6]2−, which exhibits unexpected fluorescence. The sensor shows high selectivity, rapid response and a low detection limit towards CN− in aqueous solution, hence indicating its enormous potential in practical applications. [ABSTRACT FROM AUTHOR]