Hg Compound Research Articles

Attenuation of Hg(II)-induced cellular and DNA damage in human blood cells by uric acid.

Mercury (Hg) is a widespread environmental pollutant and toxicant that induces multiple organ damage in humans and animals. Hg toxicity is mediated by the induction of oxidative stress in the target cells. We used uric acid (UA), a potent antioxidant found in biological fluids, to protect human red blood cells (RBC) and lymphocytes against Hg-mediated cell, organelle, and genotoxicity. RBCs were incubated with mercuric chloride (HgCl2), an Hg(II) compound, either alone or in the presence of UA. Incubation of RBCs with only HgCl2 increased the production of nitrogen and oxygen radical species, enhanced methemoglobin levels, heme degradation, free ferrous iron, oxidation of proteins and membrane lipids, and reduced the antioxidant capacity of cells. UA enhanced the antioxidant capacity of RBCs and restored metabolic, plasma membrane-bound, and antioxidant enzyme activities. Scanning electron microscopy showed that UA prevented HgCl2-mediated morphological changes in RBCs. HgCl2 dissipated the mitochondrial membrane potential and increased lysosomal membrane damage in lymphocytes, but UA pre-treatment attenuated these effects. Genotoxicity analysis by comet assay showed that UA protected lymphocyte DNA from HgCl2-induced damage. Importantly, UA itself did not exhibit any deleterious effects on RBCs or lymphocytes. Thus, UA protects human blood cells from Hg(II)-mediated oxidative damage, reducing the harmful effects of this extremely toxic metal. We suggest that UA has a similar protective role in plasma against heavy metal toxicity.

Probable thermoelectric materials for promising candidate of optoelectronics for Ba‐based complex perovskite compounds

Structural parameters, electronic band structure, optical spectra, and thermoelectric properties of trigonal Ba3B(Nb, Ta)2O9(B═Sr, Mg, Ca, Hg, Zn, Fe, Ni, Mn, Co, and Ca) compound materials are investigated. The computations are performed using density-functional calculations within the generalized gradient approximation. The calculated a and c parameters agree with those of the experiment to within 2%. The Ba3B(Nb, Ta)2O9(B=Sr,Mg,Ca, Hg, Zn, Fe, Ni, Mn, Co, and Ca) materials are found to be semiconductors with a band-gap energy varying from 0.82 to 3.17 eV. A metallic character is observed in Ba3B(Nb, Ta)2O9(B═Ni, Mn, and Co) compounds indicating the presence of conductivity features. A small carrier effective mass indicates the increase of the electron mobility leading to a high n-type conductivity. The p states dominate the lower valence band region. The optical spectra show an anisotropic character between x and z directions. The excitonic effects tend to increase the strength of the oscillator at M0 and M points. The effect is reduced when increasing the photon energy, indicating that the Ba3BB2'O9 compound can be used for devices such as Bragg's reflectors, and optical and optoelectronic devices. The calculations were performed using the BoltzTrap code, which depends on the semi-classical Boltzmann transport equation. The Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and the figure of merit for Ba3(Fe, Sr, Hg, Zn)B′2O9 are calculated. At higher temperatures, the mobility increases by reducing the electrical conductivity. Ba3(Fe, Sr, Hg, Zn) B2' O9 shows a considerable thermoelectric performance accompanied by a sign point figure of merit larger than many full perovskites reported till date.

Remediation Effect of Biochar on Heavy Metal Contaminated Soil

The remediation effect of biochar on Cu, Cd, Pb and Hg compound contaminated soil was studied by adding different concentrations (0%, 5%, 10%) of pig manure carbon and fruit charcoal into the soil contaminated by tailings by biochar and plant pot experiment. The results showed that the addition of biochar could effectively reduce the content of heavy metals in soil, and the effect of fruit charcoal was significantly better than that of pig manure charcoal, and when the addition of fruit charcoal was 10%, the remediation effect of copper, cadmium, lead and mercury compound contaminated soil was the best.

Migration and identification of mercury species in wet flue gas desulfurization system using temperature programmed decomposition

The environmental problem concerning Hg pollution has received worldwide attention. Coal fired power plants are responsible for large amounts of Hg emission and produce abundant by-products in particular gypsum which is capable of extensive use. In this study, the migration of Hg in the gypsum production process and effluent treatment process in a typical wet flue gas desulfurization (WFGD) system was investigated and the temperature programmed decomposition technique was applied to identified Hg species in these products. Hg concentration in both the solid and liquid fraction of samples obtained in wet flue gas desulfurization system were determined by atomic fluorescence spectroscopy. The results indicated that gypsum accounted for a small proportion (29.9%) of Hg while the majority of Hg was transported to effluent treatment process where over 99.6% Hg was removed. The amount of Hg discharged from WFGD in the drainage, gypsum, and desulfurization sludge were 0.04 t/yr, 13.56 t/yr, and 9.56 t/yr, respectively. Desulfurization environment promoted HgS formation and lead to HgS being dominant in gypsum. The alkaline environment in the effluent treatment process contributed to the formation of HgO which was regarded as the primary Hg compound and accounted for 49.5%, 54.8%, and 78.5% of the total Hg in the neutralization tank, precipitation tank, and flocculation tank, respectively. The occurrence of HgCl2 in the solid fraction attributed to absorption of solid particles when it precipitated and was enhanced by the addition of chemicals. There was no obvious difference in the proportion of HgSO4 in the effluent treatment process. Systematic studies on difference in the partitioning of Hg species enables a better understanding on Hg behavior and provides conferences on targeting removal of Hg species in WFGD system.

A novel Er–Hg compound: Preparation, structure and characterization

A novel erbium-mercury complex [Er(HIA)3(H2O)2]n [0.5n (2,6-NA)](nHgBr4) (denoted as compound 1, HIA = isonicotinic acid; 2,6-NA = 2,6-Naphthalenedisulfonic acid) has been synthesized via a hydrothermal reaction and characterized by single crystal X-ray diffraction technique. Compound 1 features a one-dimensional (1-D) chain-like structure. A solid state photoluminescence measurement revealed that there are two upconversion emission peaks at 487 nm and 529 nm, of which the latter is stronger. These peaks can be assigned to the characteristic emission of 4f electron intrashell transitions of Er3+ ions 4F7/2 → 4I15/2 and 2H11/2 → 4I15/2. A energy transfer mechanism of photoluminescence emission was described using an energy state diagram of Er3+ ions and isonicotinic acid ligand. Compound 1 shows CIE chromaticity coordinates in the green region (0.1559, 0.5611). Compound 1 has a wide band gap of 2.05 eV, which was revealed by a solid-state UV/Vis diffuse reflection experiment.

Exploring the electronic structure and stability of HgF6: Exact 2-Component (X2C) relativistic DFT and NEVPT2 studies

As a group 12 element, mercury locating at the sixth row with a valent electronic configuration of 5d106s2 has been treated as a main group element featuring +I and +II oxidation states for a long time. C. K. Jørgensen conjectured the existences of HgF4 and HgF6 molecules in early 1960s, where HgF4 was first synthesized in 2007, but HgF6 as the Hg(+VI) compound was less known. In this paper we explored the electronic structure and decomposition paths of HgF6 by scalar (X1C) and 2-component relativistic (X2C) density functional calculations and more accurate multi-reference NEVPT2 calculations. It is found that the HgF6 molecule, where the mercury atom presents an extraordinary high oxidation state of +VI, is protected by a considerable barrier height of about 22 kcal/mol for the decomposition into HgF4 and two isolated fluorine atoms. The results propose that HgF6 is kinetically stable and may exist under exorbitant conditions.

Mercury and methylmercury concentrations, sources and distribution in submarine canyon sediments (Capbreton, SW France): Implications for the net methylmercury production

Submarine canyons are important stocks of commercial interest fish, whose consumption is one of the main monomethymercury (MeHg) exposure to humans. Currently, biogeochemistry of mercury in those biologically productive system is unknown. In this work, inorganic mercury (Hg(II)) and organic mercury (MeHg) distributions were measured in sedimentary accumulative zones (slopes and terraces) against adjacent continental shelf sediments. Hg compound concentrations in these sediments show a huge range of concentrations (Hg(II) ranging from 18 to 973 ng g−1 and MeHg ranging from 0.07 to 2.03 ng g−1) exhibiting factors 50 and 20 fold, respectively. Higher values of mercury compounds were observed in canyon locations suggesting a high accumulation of mercury associated with higher values of clay fraction and organic matter content. The reactivity of mercury was investigated in sediment of three locations along Capbreton submarine canyon axis using slurry incubations experiments and isotopic tracers. Specific methylation and demethylation rate constants (kM and kD) were calculated. Results clearly showed that MeHg concentrations in these sediments are controlled by competing and simultaneous methylation and demethylation reactions mainly mediated by biotic process. Mercury reactivity was found higher in coastal stations compared to the offshore station due to more labile organic matter which may stimulate microbial activities. However, higher net MeHg production was estimated for the offshore station due to high Hg(II) concentrations suggesting a potential MeHg source for such marine environments.

Ab initio effective Hamiltonians for cuprate superconductors

Ab initio low-energy effective Hamiltonians of two typical high-temperature copper-oxide superconductors, whose mother compounds are ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ and ${\mathrm{HgBa}}_{2}{\mathrm{CuO}}_{4}$, are derived by utilizing the multiscale ab initio scheme for correlated electrons (MACE). The effective Hamiltonians obtained in the present study serve as platforms of future studies to accurately solve the low-energy effective Hamiltonians beyond the density functional theory. It allows further study on the superconducting mechanism from first principles and a quantitative basis without adjustable parameters not only for the available cuprates but also for future design of higher ${T}_{\mathrm{c}}$ in general. More concretely, we derive effective Hamiltonians for three variations: (1) a one-band Hamiltonian for the antibonding orbital generated from strongly hybridized Cu $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and O $2{p}_{\ensuremath{\sigma}}$ orbitals, (2) a two-band Hamiltonian constructed from the antibonding orbital and Cu $3{d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbital hybridized mainly with the apex oxygen ${p}_{z}$ orbital, and (3) a three-band Hamiltonian consisting mainly of Cu $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals and two O $2{p}_{\ensuremath{\sigma}}$ orbitals. Differences between the Hamiltonians for ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ and ${\mathrm{HgBa}}_{2}{\mathrm{CuO}}_{4}$, which have relatively low and high critical temperatures ${T}_{\mathrm{c}}$, respectively, at optimally doped compounds, are elucidated. The main differences are summarized as follows: (i) the oxygen $2{p}_{\ensuremath{\sigma}}$ orbitals are farther ($\ensuremath{\sim}3.7$ eV) below from the Cu ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbital in the case of the La compound than the Hg compound ($\ensuremath{\sim}2.4$ eV) in the three-band Hamiltonian. This causes a substantial difference in the character of the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}\ensuremath{-}2{p}_{\ensuremath{\sigma}}$ antibonding band at the Fermi level and makes the effective onsite Coulomb interaction $U$ larger for the La compound than the Hg compound for the two- and one-band Hamiltonians. (ii) The ratio of the second-neighbor to the nearest transfer ${t}^{\ensuremath{'}}/t$ is also substantially different (0.26 for the Hg and 0.15 for the La compound) in the one-band Hamiltonian. Heavier entanglement of the two bands in the two-band Hamiltonian implies that the two-band rather than the one-band Hamiltonian is more appropriate for the La compound. The relevance of the three-band description is also discussed especially for the Hg compound.

Drivers of the accumulation of mercury and organochlorine pollutants in Mediterranean lean fish and dietary significance

An integrated assessment of lean fish of commercial value as Hg and organochlorine compound source into the population of the Balearic Islands were reported. Dependences between pollutant concentrations, trophic level, fish species, specimen weight and physical-chemical properties were evaluated.Hg and total DDTs showed highest variability between fish species whereas PCBs and HCB displayed more constant median values. The organochlorine compounds found in highest concentrations were those with highest hydrophobicity, consistently with their higher bioaccumulation potential. These pollutant concentrations were higher in Mediterranean than Atlantic fish. Higher median total DDT and PCBs concentrations were also observed in the third than the second trophic level species. The observed concentrations were below the threshold recommended by the EU for human consumption (75ng/g wet weight).The Hg concentrations were higher in Mediterranean than Atlantic fish, with average values of 1.5μg/g ww and 0.43μg/g ww, respectively. Forty-one percent of the specimens from the Mediterranean and 25% of dusky grouper specimens from the Atlantic Ocean showed Hg concentrations above the EU recommended limits for human consumption, either 0.5μg/g ww or 1μg/g ww.In the third trophic level, a significant dependence between median Hg concentrations and weight of each studied species was observed, which remained significant in specimen weight correlations. Independent species correlations of Hg concentrations vs individual weight generally showed higher concentrations at higher weight. Weight/size of the individuals was therefore an important factor for Hg accumulation but the trend was modulated by a species effect.Extrapolation of the observed Hg concentrations in Mediterranean fish to Provisional Tolerable Weekly Intakes (PTWIs) showed higher intakes than the thresholds recommended by EFSA for adults and children, 110% and 140%, respectively. The estimated PTWIs for MeHg corresponded to 310% and 400% of the recommended threshold values. The PTWI values for organochlorine compounds were lower than those recommended.

A multiscale study of mercury transformations and dynamics at the chemocline of the Petit-Saut tropical reservoir (French Guiana)

This study investigated, on both metric and centimetric scales, mercury (Hg) transformations and dynamics within a water column chemocline of a tropical reservoir. Data collected included conventional measurement of Hg in water samples, diffusive gradients in thin-films (DGT) assessments, and thermodynamic speciation modeling in order to portray the biogeochemical processes that control elemental Hg (EM) and dissolved monomethylated Hg (MeHgD) production. The primary contribution of this study is demonstration that the DGT technique can be successfully implemented to examine labile Hg compound mobilization, and estimation of how local substratum facilitates Hg reduction and methylation reactions. DGT profiles with a resolution of 1cm revealed a fine sequence of prominent Hg reduction/oxidation reactions at the chemocline level. This is interpreted as a manifestation of both: i) kinetic effects capable of arising inside the diffusive layer of DGT devices, and ii) extremely localized production or consumption of reducible and methylable Hg. Another key result obtained at the metric scale is that EM and MeHgD production at a water column chemocline are intricately linked, as both are fueled by nutrients episodically released during the decomposition of falling epilimnetic organic particles or inhibited by dissolved organic matter and inorganic compounds continuously transported from the deeper monimolimnion. Finally, it is worth noting that the chemocline acts as an accumulation and recycling domain for falling MeHg-loaded organic particles, whereas the high primary productivity layer in the epilimnion represents the principal reactor with respect to Hg methylation and reduction.

A review on thimerosal: an irreplaceable element of long-term immunisation strategy in low income countries

Thimerosal, an organic-mercury (Hg) compound containing 49.55% Hg by weight, is added to vaccines as a preservative permitting formulation of multi-dose vaccine vials. Being a derivative of ethylmercury, it has been linked with autism as a possible risk factor based on the assumption that exposure to ethylmercury would have similar neurotoxic effects as another mercurial compound, methylmercury. In 1999, AAP issued a joint statement emphasising the removal of thimerosal from vaccines. Subsequently, several studies have been conducted; those showing positive association between thimerosal exposure and autism have been recognised to be fraught with methodological flaws. On the other hand, many well controlled studies have failed to find any such causal relation and there are others that have clearly demonstrated a much favourable kinetic profile of ethylmercury as compared to methylmercury. Owing to the lack of data, AAP retired its original statement in 2002. Recently, thimerosal has been exempted from regulation by Minamata Convention on Mercury resulting in the continued use of low cost thimerosal containing vaccines in low income countries which cannot afford to run their immunisation program using single dose thimerosal free vaccines, that comparatively cost much higher, as is the case in high income countries. Some bodies view this as a discrimination on the basis of wealth of a nation and have opposed this decision. This review presents various studies regarding the causal association between thimerosal containing vaccines and autism. The current evidence fails to support any such association. Hence this review supports the exemption of thimerosal from regulation and also justifies its use in LICs for uninterrupted vaccination of the most vulnerable population.

Natural Hg isotopic composition of different Hg compounds in mammal tissues as a proxy for in vivo breakdown of toxic methylmercury.

In the last decade, specific attention has been paid to total mercury (HgT) stable isotopic composition, especially in natural samples such as aquatic organisms, due to its potential to track the cycle of this toxic element in the environment. Here, we investigated Hg Compound Specific stable Isotopic Composition (CSIC) of natural inorganic Hg (iHg) and methylmercury (MMHg) in various tissues of aquatic mammals (Beluga whale from the Arctic marine environment and seals from the freshwater lake Baikal, Russia). In seals' organs the variation in mass dependent fractionation (MDF, δ(202)Hg) for total Hg was significantly correlated to the respective fraction of iHg and MMHg compounds, with MMHg being enriched by ∼ 3‰ in heavier isotopes relative to iHg. On the other hand, we observe insignificant variation in Hg mass independent isotope fractionation (MIF, Δ(199)Hg) among iHg and MMHg in all organs for the same mammal species and MMHg in prey items. MIF signatures suggest that both MMHg and iHg in aquatic mammals have the same origin (i.e., MMHg from food), and are representative of Hg photochemistry in the water column of the mammal ecosystem. MDF signatures of Hg compounds indicate that MMHg is demethylated in vivo before being stored in the muscle, and the iHg formed is stored in the liver, and to a lesser extent in the kidney, before excretion. Thus, Hg CSIC analysis in mammals can be a powerful tool for tracing the metabolic response to Hg exposure.

Syntheses, crystal structures and steady state and time-resolved fluorescence properties of a PET based macrocycle and its dinuclear ZnII/CdII/HgII complexes.

The work in the present investigation reports the syntheses, crystal structures, ESI-MS (positive) and steady state and time resolved photophysical properties of a tetraaminodiphenol macrocyclic ligand H2L (saturated analogue of a tetraiminodiphenol macrocycle obtained on 2 + 2 condensation of 4-ethyl-2,6-diformylphenol and 2,2-dimethyl-1,3-diaminopropane) and its three dinuclear d10 metal ion (ZnII, CdII and HgII) complexes having compositions [ZnLCl2]·2CH3OH (1), [CdL(μ-H2O)(H2O)2](NO3)2·4H2O (2) and [HgLCl2] (3). H2L is colorless and weakly fluorescent, Cd compound 2 is colorless and more weakly fluorescent, Zn compound 1 is colorless and highly fluorescent and Hg compound 3 is yellow and nonemissive. The order of the radiative rate constant (Kr), obtained from time-resolved studies, corroborates the order of quantum yields, obtained from steady state studies: 1 (φ = 0.12; Kr = 116.6 × 106 s-1) ≫ H2L (φ = 0.005; Kr = 7.726 × 106 s-1) > Cd compound 2 (φ = 0.0014; Kr = 0.675 × 106 s-1). Spectrophotometric and steady state/time-resolved spectrofluorimetric titrations of H2L with ZnII, CdII and HgII have been performed. The relative fluorescence efficiencies of H2L, H2L + various single metal ions (ZnII, CdII, HgII, CuII, NiII, CoII, FeII, MnII) and H2L + ZnII + another metal ion (metal ion competition study) have been studied. Relative fluorescence efficiency can be well rationalized in terms of photoinduced electron transfer (PET), perturbation of PET by metal coordination (chelation enhanced fluorescence, CHEF), heavy metal ion effect (spin-orbit coupling) and fluorescence quenching mechanism. It has been established from comparative fluorescence spectra of 4-ethylphenol, H2L and 1 that H2L can be reasonably considered as a PET species in which the fluorophore is 4-ethylphenol. The binding constants, as determined from titration experiments, qualitatively corroborate the results of metal ion competition studies. The modulation of the absorption spectra and color of the H2L-HgII solution in the presence of various diamagnetic metal ions has been explored. Significant aspects of structures and spectroscopic properties have been discussed.

Speciation of mercury in FGD gypsum and mercury emission during the wallboard production in China

During combustion of pulverized coals, most of the mercury (Hg) in coal volatilizes. With the wide use of dry and wet scrubber systems for flue gas desulfurization (FGD), various amounts of Hg are captured by coal combustion byproducts, such as, FGD gypsum. The specification of Hg in FGD gypsum is essential not only to determine the risk when the wastes are recycled or disposed but also to understand the behavior of Hg during coal combustion and the mechanisms of Hg oxidation along the flue gas path. In this study, a temperature-programmed decomposition technique was used in order to acquire an understanding of the Hg species associated with FGD gypsum. A series of Hg reference compounds were used to obtain the characteristic temperature of decomposition for each Hg compound. The decomposition temperature of the Hg species is in an increasing order as Hg2SO4<Hg2Cl2<HgCl2<black HgS<HgO<red HgS<HgSO4. The results also indicate that HgCl2 and HgS are the primary Hg compounds in FGD gypsum samples. Hg stability during the reutilization of FGD gypsum is important due to its health and environmental impact, and its value in improving the Hg emission inventory. The industrial calcining process of wallboard production is simulated in order to determine the Hg emission percentage during the reutilization of FGD gypsum. Results indicate that 12.1–55.1% of total Hg would be emitted from FGD gypsum in this process. A larger percentage of Hg will be emitted when the proportion of Hg2Cl2 and HgCl2 is higher. The Hg re-emissions from FGD gypsum during wallboard production in China were estimated to be 4.7tons in 2008.

Application of a selective extraction method for methylmercury compound specific stable isotope analysis (MeHg-CSIA) in biological materials

Methylmercury (MeHg) is a key organometallic compound of Hg and a potent neurotoxin that bioaccumulates along food webs. Hg speciation analysis of environmental samples is essential for understanding the sources, dynamics and impact of MeHg in ecosystems. Hg stable isotope analysis is a new tool to try and answer outstanding questions on Hg cycling, but has thus far been applied essentially to total Hg fractions in biota. Hg compound specific stable isotope analysis is a new approach to understand the isotopic fraction of Hg at the molecular level. In this study, we developed a robust, accurate and precise selective extraction method for MeHg in biological samples for subsequent quantification by AFS or ID-GC-ICPMS and determination of the isotopic composition by CV-MC-ICPMS. The method consists of an optimized two-step extraction/back-extraction technique validated using a MeHg standard solution and seven certified reference materials with a large range of total Hg and MeHg values. In the final extract solution, MeHg purification yields were higher than 97%, and accurate MeHg concentrations were obtained for the different certified materials. High precision MeHg stable isotope analysis (2SD ≈ 0.1‰) by CV-MC-ICPMS showed a four-fold improvement in precision for this method relative to previous on-line GC-MC-ICPMS measurements. Reference values for total Hg and MeHg compound specific stable isotope values are given for NRCC-TORT-2, NRCC-DOLT-4, IRMM-ERM-CE464, IRMM-BCR-463, IRMM-BCR-414, NIST-SRM-1947 and NIST-QC03LH03 reference materials.

Spallation reaction and the probe of nuclear dissipation with excitation energy at scission

We study in the framework of the Langevin model the influence of initial excitation energy(E*) of Hg compound nuclei(CNs) on the sensitivity of the excitation energy at scission(Esc*) to the nuclear friction strength(β).It is shown that the sensitivity is enhanced substantially with increasing E*.Moreover,we find that the significant sensitivity of Esc* to β at high E*is little affected by a marked difference in the neutron-to-proton ratio of a CN and in its size and fissility.Our findings suggest that,on the experimental side,a measurement of Esc* in energetic proton-induced spallation reactions can provide not only a sensitive but also a robust probe of nuclear dissipation in fission of highly excited nuclei.Further development of a suitable approach to spallation reaction is discussed.

Variable transformations of di[4-(pyridin-2-yl)pyrimidinyl]disulfide induced by different metal salts

Assembly of three different metal salts with 2-ppds ( 2-ppds = di[4-(pyridin-2-yl)pyrimidinyl]disulfide) under the same conditions produced three totally distinct coordination compounds. In the presence of Cu(NO 3) 2, a dinuclear Cu(I) macrocyclic compound [Cu 2( 2-ppts) 2](NO 3) 2 ( 1) together with a mononuclear Cu(II) compound [Cu( 2-pps)](NO 3) 2 ( 2) are formed, of which the initial 2-ppds ligand is in situ converted into its trisulfide 2-ppts ( 2-ppts = di[4-(pyridin-2-yl)pyrimidinyl]trisulfide) and monosulfide 2-pps ( 2-pps = di[4-(pyridin-2-yl)pyrimidinyl]sulfide), respectively. Replacement of Cu(NO 3) 2 by Zn(NO 3) 2 affords a mononuclear Zn(II) coordination compound [Zn( 2-pps)(NO 3) 2] ( 3). The use of HgCl 2 results in a dinuclear Hg(II) compound [Hg 4Cl 8( 2-ppds) 2] ( 4) without any change on 2-ppds. All coordination compounds have been structurally ascertained by X-ray crystallography. Besides, ESI-MS examination of the mother solution for each compound has also been carried out to further understand the impacts of different metal salts.

Speciation of mercury in fly ashes by temperature programmed decomposition

Mercury (Hg) is a toxic trace element which is emitted mostly in gas phase during coal combustion, although some Hg compounds may be retained in the fly ashes depending on the characteristics of the ashes and process conditions. To improve the retention of Hg in the fly ashes a good knowledge of the capture mechanism and Hg species present in the fly ashes is essential. The temperature programmed decomposition technique was chosen to identify the Hg species present in fly ashes obtained from two Pulverized Coal Combustion (PCC) plants and a Fluidized Bed Combustion (FBC) plant. The fly ashes were then used as Hg sorbents in a simulated flue gas of coal combustion and gasification. The Hg compounds found in the fly ash from the FBC plant after elemental mercury retention were mainly HgCl2 and HgSO4. The Hg species present in the two fly ashes from the two PCC plants were HgCl2 and Hg0. The Hg species formed in the coal gasification atmosphere was HgS for all three fly ashes. The only Hg compound identified in the fly ashes after the retention of mercury chloride was HgCl2.

Zinc, Cadmium, and Mercury Complexes with Fluorinated Selenolate Ligands

Reductive cleavage of C(6)F(5)SeSeC(6)F(5) with elemental M (M = Zn, Cd, and Hg) in pyridine results in the formation of (py)(2)Zn(SeC(6)F(5))(2), (py)(2)Cd(SeC(6)F(5))(2), and Hg(SeC(6)F(5))(2). Structural characterization of the Zn and Cd compounds reveals tetrahedral coordination environments, while the Hg compound shows a complicated series of linear structures with two short, nearly linear Hg-Se bonds, up to two longer and perpendicular Hg...Se interactions, and no coordinated pyridine ligands. All three compounds exhibit well-defined intermolecular pi-pi-stacking interactions in the solid state. They are volatile and decompose at elevated temperatures to give MSe and either (SeC(6)F(5))(2) or Se(C(6)F(5))(2).

Highly sensitive chemosensor for Cu(II) and Hg(II) based on the tripodal rhodamine receptor

A new flexible tripodal compound 1 linked with three rhodamine groups as fluorophores and recognition sites was synthesized and its sensing behavior toward metal ions was investigated by UV–vis and fluorescence spectroscopy methods. It exhibited excellent selectivity for Cu(II) over miscellaneous metal ions including Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Al(III), Mg(II), Ca(II), Sr(II ), Na(I), and K(I). While the fluorescence of the 1-Cu(II) complex could be enhanced significantly upon the addition of Hg(II) compound 1 may therefore be applicable as an OFF-ON fluorescent chemosensor for Cu(II) and Hg(II).