Thiol-functionalized MCM-48: an Effective Absorbent of Mercury Ions

Mercaptopropyl groups were grafted onto the pore walls of mesoporous molecular sieves MCM-48. The pore structures were characterized by powder X-ray diffraction and N2 adsorption analYSiS. Elemental analysis confirmed that the material with high organic moiety （2.2 mmol/g） had been obtained. ^13C MAS NMR verified the tethered organic groups. The thiol-functionalized MCM-48 showed effective capture of mercury ions, and all of the organic ligands were accessible for the binding of mercury ions.

A Rational Designed Dual-channel Chemosensor for Mercury Ions Based on Hydrolysis of Schiff Base

A bilateral Schiff base is reported for the colorimetric and fluorometric dual-channel sensing of Hg^(2+)ions by taking advantage of the hydrolysis of carbon-nitrogen double bond,altering an ICT state mechanism and then Hg^(2+) ions coordinating with amino moieties of 1,5-DAN and leading to the aggregation of 1,5-DAN.Meanwhile,it formed a stable neutral complex of amino-Hg-amino.In addition,test strips based on L were fabricated,which also exhibited a good selectivity to Hg^(2+) as in solution.This work provides a novel approach for the selective recognition of mercury ions.Notably,the color changes are very significant and all the recognition processes can be observed by the naked eyes.We believe the test strips can act as a convenient and efficient Hg^(2+) test kit.

Magnetically separated and N, S co-doped mesoporous carbon microspheres for the removal of mercury ions

Magnetically separated and N, S co-doped mesoporous carbon microspheres （NIS-MCMs/Fe304） are fabricated by encapsulating Si02 nanoparticles within N, S-containing polymer microspheres which were prepared using resorcinol/formaldehyde as the carbon source and cysteine as the nitrogen and sulfur co-precursors, followed by the carbonization process, silica template removal, and the introduction of Fe3O4 into the carbon mesopores. N/S-MCMs/Fe3O4 exhibits an enhanced Hg2＋ adsorption capacity of 74.5 rag/g, and the adsorbent can be conveniently and rapidly separated from wastewater using an external magnetic field. This study opens up new opportunities to synthesize well- developed, carbon-based materials as an adsorbent for potential applications in the removal of mercury ions from wastewater.

Pseudo-crown ether having AIE and PET effects from a TPE-CD conjugate for highly selective detection of mercury ions

A new tetraphenylethylene-cyclodextrin (TPE-CD) conjugate with a linkage composed of long triethylene glycol chain and triazole ring on the CD rim has been designed and synthesized. The TPE-CD conjugate exists in a stretched form in DMSO and enhances its fluorescence after addition of a small amount of water due to aggregation-induced emission (AIE) effect. However, in the presence of a large amount of water, the TPE unit will enter the cyclodextrin cavity to form a folded self-inclusion compound. In the self-inclusion compound, not only nitrogen-containing pseudo-crown ether is formed but also arouses photo-induced electron transfer (PET) process from nitrogen atoms of triazole ring to TPE unit and quenches the fluorescence although more aggregation occurs in more water. This is the first finding that TPE-macrocycle conjugate can form pseudo-crown ether and has both the AIE phenomenon and the PET effect. Interestingly, only mercury ion arouses the fluorescence recover of the self-inclusion compound by entering the pseudo-crown ether cavity and blocking the PET process by binding to the nitrogen atoms, while other tested metal ions almost have no effect on the fluorescence. Therefore, the TPE-CD conjugate can be used for the highly selective fluorescence "Turn-On" detection of Hg^(2+).

1-Pyrenecarboxaldehyde thiosemicarbazone:A novel fluorescent molecular sensor towards mercury(Ⅱ) ion

A novel and simple fluorescent molecular sensor,1-pyrenecarboxaldehyde thiosemicarbazone（Hpytsc）,was synthesized.Its higher sensitivity and selectivity to mercury（Ⅱ） ion were studied through absorption and emission channels.The UV-vis spectra show that the increasing mercury（Ⅱ） ion concentrations result in the decreasing absorption intensity.The fluorescence monomer emission of Hpytsc is enhanced upon binding mercury（Ⅱ） ion,which should be due to the 1：1 complex formation between Hpytsc and metal ion.

Generation of Continuous-Wave 194 nm Laser for Mercury Ion Optical Frequency Standard

A 194-nm cw laser is an essential part in the mercury ion optical frequency standard. We report the generation of over 2mW continuous-wave radiation at 194nm in a beta barium borate crystal using a simple sum frequency mixing （SFM） system. One source beams at 718nm is resonantly enhanced with a cavity and the other at 266mn makes a single pass. Considering the walk-off effect in SFM, the source beam waists are designed to be elliptical, thus the conversion efficiency can be promoted. The 266-nm beam produced by frequency doubling of 532-nm laser is shaped close to the diffraction limit to achieve better mode matching.

Effects of 1,2,4-Trichlorobenzene and Mercury Ion Stress on Ca^2+ Fluxion and Protein Phosphorylation in Rice

The effects of 5 mg/L 1,2,4-trichlorobenzene （TCB） and 0.1 mmol/L mercury ion （Hg^2＋） stresses on Ca^2＋ fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca^2＋ absorption in rice leaves and Ca^2＋ transportation from roots to leaves were promoted significantly in response to Hg^2＋ and TCB treatments for 4-48 h. The Ca^2＋ absorption peaks presented in the leaves when the rice seedlings were exposed to Hg^2＋ for 8-12 h or to TCB for 12-24 h. Several Ca^2＋ absorption peaks presented in the roots during rice seedlings being exposed to Hg^2＋ and TCB, and the first Ca^2＋ absorption peak was at 8 h after being exposed to Hg^2＋ and TCB The result of isotope exchange kinetic analysis confirmed that short-term （8 h） Hg^2＋ and TCB stresses caused Ca^2＋ channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots （TCB treatment for 4-8 h） and leaves （TCB treatment for 4-24 h）, and short-term （4-8 h） Hg^2＋ stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca^2＋ absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg^2＋ stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg^2＋ treatment inhibited protein phosphorylation in rice roots, and Hg^2＋ treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg^2＋ stress.

Optimal Microwave Radiation Field Parameters for Mercury Ion Microwave Frequency Standards

We propose a method to determine the optimal power of the microwave resonance transition that simultaneously improves the signal-to-noise ratio and reduces line width based on saturation broadening theory and experiment. Saturation broadening spectra of the ground state hyperfine transition of trapped 199Hg＋ ions are measured and analyzed. The value of the optimal microwave power is obtained by using the proposed method and is verified. Rabi oscillations decay spectra of trapped 199Hg＋ ions are observed and the optimal microwave irradiation time for the maximum transition signal intensity is determined. This work will help to improve the short-term frequency stability of the mercury ion microwave frequency standard.

High extraction ability of 1,3-dialkynyl calixarene towards mercury(Ⅱ) ion

The reaction of 1,3-dipropyn-2-yloxycalix[4]arene with mercury（U） acetate could give mercury-containing alkynyl calixarene polymer. The extraction behavior of 1,3-dipropyn-2-yl-oxycalix[4]arene towards mercury（Ⅱ） ion was examined. When the mole ratio of Hg^2＋/calixarene was 1：1, the extractive percent can reach to 99.1%, and the extraction capacity was up to 431 mg/g. It could also decrease the Hg^2＋ concentration from 5 to 0.85 mg/L, which was only 17% of the national standard of effluent and satisfied the national standard of drinking water. The extraction process included chemical reaction.

Synthesis of Carbon dots from Biomass Chenpi for the Detection of Hg^(2+)

Biomass-derived carbon dots(C-dots)are considered a very important carbon material in metal ion detection of their small environmental impact,simple preparation process,and relatively low cost.A green approach for synthesizing biomass-derived C-dots from Chenpi using a hydrothermal method without further processing is proposed in the present study.The as-synthesized C-dots show excellent fluorescence properties,superior resistance to UV irradiation photobleaching,and high photostability in salt-containing solutions.The C-dots were used in the form of label-free fluorescent probes for sensitively detecting Hg^(2+)selectively.The outcome relationship behaved linearly and was established based on a given range between 10–300 nM concentration,with a detection limit of 7.0 nM.This green strategy obtains a high C-dot quantum yield of 10.8%and satisfactory results in detecting Hg^(2+)in actual water samples.

Development of a test strip based on DNA-functionalized gold nanoparticles for rapid detection of mercury(II) ions

A rapid,sensitive,selective and reliable strip assay based on DNA-functionalized gold nanoparticles for Hg^（2＋） detection has been developed,with a detection limit 5 nmol/L.The measurement principle was based on thymine-Hg^（2＋）-thymine（T-Hg^（2＋）-T） coordination chemistry and streptavidin-biotin interaction.The major advantages of this assay are that results can be read visually without any instrument in less than 10 min and that it does not require any sample pretreatment.

Au/Ag_(2)S dimeric nanostructures for highly specific plasmonic sensing of mercury(Ⅱ)

Although many plasmonic nanosenosrs have been established for the detection of mercury(Ⅱ)(Hg^(2+)),few of them is feasible for analyzing natural samples with very complex matrices because of insufficient method selectivity.To address this challenge,we propose an epitaxial and lattice-mismatch approach to the synthesis of a unique Au/Ag_(2)S dimeric nanostructure,which consists of an Au segment with excellent plasmonic characteristics,and a highly stable Ag_(2)S portion with minimum solubility product (K_(sp)(Ag_(2)S)=6.3×10^(-50)).The detection relies on the chemical conversion of Ag_(2)S to HgS when reacting with Hg^(2+),resulting in a red shift in the absorption band of the connecting Au NPs.The concurrent color changes of the solution from gray purple to dark green and finally to navy correlate well with Hg^(2+)concentration,thus enables UV-vis quantitation and a naked-eye readout of the Hg^(2+)concentration.This method exhibits superior selectivity towards Hg^(2+) over other interfering ions tested because Hg^(2+) is the only ion that can react with Ag_(2)S to form HgS with even smaller solubility product (K_(sp)(HgS)=4×10^(-53)).The detection limit of this method is 1.21μmol/L,calculated by the signal-to-noise of 3.The practicability of the method was verified by analyzing the Hg^(2+)in sewage water samples without sample pretreatment with satisfactory recoveries (93.1%-102.8%) and relative standard deviations (1.38%-2.89%).We believe this method holds great potential for on-the-spot detection of Hg^(2+) in environmental water samples with complex matrices.

Establishment of a new molecular model for mercury determination verified by single crystal X-ray diffraction,spectroscopic analysis and biological potentials

A wide variety of molecular probes have been developed for real-time analysis,but most of organic fluorophores possess small Stokes shifts and self-absorption or inner filter effect that could not be avoided.In this study,a new dicyanoisophorone-based derivative(E)-0-(4-(2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)phenyl)diphenylphosphinothioate(λ_(ex)=405 nm,X_(em)=551 nm,denoted as ICM-S) with strong push-pull electron effect has been afforded and it exhibits red shift for absorption from 407 nm to 426 nm with distinct color change from pale yellow to deep yellow upon exposure to Hg~(2+).Moreover,an easily distinguishable fluorescence color change follows the route from green,yellow to red in the presence of Hg~(2+) over the range of 0-90 μmol/L(detection limit=137 nmol/L)can be observed by the naked eye under a UV lamp irradiation.Chlorodiphenylphosphine and sublimedsulfur are incorpo rated as re s ponsive sites and P-O bond has been cleaved upon the addition of mercu ry ions.During the recognition process,such dicyanoisophorone dye(ICM-S) has been evolved to 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile(ICM-OH).Clear evidences in the chemical processes can be identified via single crystal X-ray diffraction,spectroscopic analysis,photophysical studies and titration experiments.With the aim of exploring its potential in biological systems,its in vitro responses to Hg~(2+) have been evaluated in 293 T cells and the effectiveness in zebrafish model has also been verified.

Dual-emissive nanohybrid nanoclusters for sensitive ions of carbon dots and gold determination of mercuric

The present work reports a sensitive and selective fluorescent sensor for the detection of mercury ion, Hg（II）, by hybridizing carbon nanodots （C-dots） and gold nanoclusters （Au NCs） through intrinsic interactions of the two components. The C-dots serve as the reference signal and the Au NCs as the reporter. This method employs the specific high affinity metallophilic Hg2^-Au＋ interactions which can greatly quench the red fluorescence of Au NCs, while the blue fluorescence of C-dots is stable against Hg（II）, leading to distinct ratiometric fluorescence changes when exposed to Hg（II）. A limit of detection of 28 nM for Hg（II） in aqueous solution was estimated. Thus we applied the sensor for the detection of Hg（II） in real water samples including tap water, lake water and mineral water samples with good results. We further demonstrated that a visual chemical sensor could be manufactured by immobilizing the nanohybrid probe on a cellulose acetate circular filter paper. The paper-based sensor immediately showed a distinct fluorescence color evolution from pink to blue after exposure to a drop of the Hg（II） solution

A squaraine based fluorescent probe for mercury ion via coordination induced deaggregation signaling

Due to the high affinity between dithiocarbamate （DTC） and Hg2＋, a fluorescent probe based on squaraine chromophore with DTC side arm for Hg2＋ via coordination induced deaggregation signaling has been designed and synthesized. Squaraine has a high tendency to aggregate in aqueous solution, and such self-aggregation usually results in a dramatic absorption spectral broadening with fluorescence emission quenching. The combination of the DTC side arm of the probe with Hg2＋ induces steric hindrance, leading to the deaggregation of the dye complex, companying with a fluorescence emission restoration. In EtOH-H2O （20：80, v/v） solution, this ＂turn on＂ fluorescent probe has high selectivity and sensitivity toward Hg2＋ over other metal ions, and the limit of detection for Hg2＋ was estimated as 2.19 × 10^-8 mol/L by 3σ/k.

4-Mercaptopyridine Modified Fiber Optic Plasmonic Sensor for Sub-nM Mercury(II)Detection

In this paper,we propose and demonstrate a high-performance mercury ion sensor with sub-nM detection limit,high selectivity,and strong practicability based on the small molecule of the 4-mercaptopyridine(4-MPY)modified tilted fiber Bragg grating surface plasmon resonance(TFBG-SPR)sensing platform.The TFBG-SPR sensor has a rich mode field distribution and a narrow bandw idth,which can detect the microscopic physical and chemical reactions on the sensor surface with high sensitivity without being disturbed by the external temperature.For the environmental compatibility and highly efficient capture of the toxic mercury ion,4-MPY is modified on the sensor surface forming a stable(4-MPY)-Hg-(4-MPY)structure due to the specific combination between the nitrogen of the pyridine moiety and the Hg+via multidentate N-bonding.Moreover,gold nanoparticles(AuNPs)are connected to the sensor surface through the(4-MPY)-Hg-(4-MPY)structure,which could play an important role for signal amplification.Under the optimized conditions,the limit of detection of the sensor for mercury ions detection in the solution is as low as 1.643×10^(-10)M(0.1643 nM),and the detection range is 1×10^(-9)M-1×10^(-5)M.At the same time,the mercury ion spiked detection with tap water shows that the sensor has the good selectivity and reliability in actual water samples.We develop a valuable sensing technology for on-time environmental Hg t detection and in-vivo point of care testing in clinic applications.

Thiourea functionalized CdSe/CdS quantum dots as a fluorescent sensor for mercury ion detection

CdSe/CdS quantum dots （QDs） functionalized by thiourea （TU） were synthesized and used as a fluorescent sensor for mercury ion detection. The TU-functionalized QDs were prepared by bonding TU via electrostatic interaction to the core/shell CdSe/CdS QDs after capping with thioglycolic acid （TGA）. It was observed that the fluorescence of the functionalized QDs was quenched upon the addition of Hg^2＋. The quantitative detection of Hg^2＋ with this fluorescent sensor could be conducted based on the linear relationship between the extent of quenching and the concentration of Hg^2＋ added in the range of 1-300 μg.L^-1, A detection limit of 0.56 μg.L^-1 was achieved. The sensor showed superior selectivity for Hg^2＋ and was successfully applied to the determination of mercury in environmental samples with satisfactory results

A thermodynamic investigation on the binding of mercury ion with myelin basic protein at different temperatures

A thermodynamic study on the interaction of myelin basic protein with mercury ion was studied by using isothermal titration calonmetry,ITC,at 300.15,310.15 and 320.15 K in Tris buffer solution at pH 7.The enthalpies of MBP ＋ Hg^（2＋） interaction are reported and analysed in terms of the extended solvation model.It was found that MBP has two identical and non-cooperative binding sites for Hg^（2＋） ions.The intrinsic dissociation equilibrium constants are 99.904,112.968 and 126.724μmol/L,and the molar enthalpy of binding are -11.634,-10.768 and -10.117kJ mol^（-1） at 300.15,310.15 and 320.15 K,respectively.

MOF-derived Cu2O/Cu NPs on N-doped Porous Carbon as a Multifunctional Sensor for Mercury(Ⅱ) and Glucose with Wide Detection Range

Cu2O/Cu nanoparticles(NPs)in the nanoporous carbon matrix(designated as Cu2O/Cu@NPC)has been synthesized by in-situ calcination of a cupper-based metal-organic framework(Cu-MOF),and its morphology and composition were characterized by PXRD,SEM and Raman.Furthermore,elemental mapping and XPS analysis not only show Cu NPs is generated along with nitrogen(N)-doped carbon,but also indicate Cu2O NPs locates in the external layer of Cu@NPC.In addition,the adsorption of dye studies implies that Cu2O/Cu@NPC exhibits obvious interaction with Rhodamine B(Rh B)due to the feature of porous and N-doped structure.Cu2O/Cu@NPC has highly electrocatalytic performance for glucose and mercury(Ⅱ)with wide detection range and good stability,which can be used as a novel multifunctional sensor for glucose and mercury(Ⅱ).

The exquisite integration of ESIPT, PET and AIE for constructing fluorescent probe for Hg(II) detection and poisoning

Excessive mercury ions(Hg^(2+)) in the environment can accumulate in human body along with the food chain to cause serious physiological reactions.The fluorescence probes were considered as convenient tool with great potential for Hg^(2+) detection.Most existing probes suffer from aggregation-induced quenching(ACQ) effects and insufficient sensitivity.Herein,a novel type of fluorophore was developed by combining the aggregation-induced emission(AIE) and excited state intramolecular proton transfer(ESIPT) characteristics.Subsequently,a phenyl thioformate group with photoinduced electron transfer(PET)effect was connected to give an efficient "turn-on" probe(HTM),which exhibited good selectivity toward Hg^(2+),short response time(30 min),coupled with extremely low detection limit(LOD=1.68 nmol/L).In addition,HTM was used successfully in real samples,cells and drug evaluation,underlying the superiority of HTM to detect Hg^(2+) in practical applications.