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1.
We discuss the Coulomb fragmentation of highly charged metal clusters. The analogy with a classical conducting liquid drop is assessed from molecular dynamics calculations. Experimentally, the highly charged metal clusters are formed in collisions with highly charged ions (Xe20+, Ar11+, Ar8+, Ar3+, and O5+) at low velocity. We show new experimental data on the rate of emitted light charged particles that indicate an as yet unobserved fragmentation regime. Collisions of ions with metal clusters also offer a unique method to strongly excite the conducting electron gas within a short time of a few fs opening the possibility to study large amplitude electron dynamics and relaxation in microscopic systems.  相似文献   

2.
A simple epoxy-based polymer 1 bearing 1-naphthylamine units has been synthesized and its recognition behaviors toward various metal ions have been investigated in THF-water (8:2, v/v) solution. The designed polymer 1 was found to exhibit selective ON-OFF-type fluorosensing behavior toward Fe3+ ions over other representative metal ions such as Cu2+, Zn2+, Co2+, Ni2+, and Hg2+ ions.  相似文献   

3.
Quenching of the luminescence of carboxyl-containing polymer molecules containing a luminescent marker by transition metal ions (Cu2+, Ni2+) is observed not only in aqueous and aqueous-salt solutions, but also in polar organic solvents (methanol, ethanol, dimethylformamide). In dilute solutions, quenching refl ects binding of metal ions with the polymer and changes in the degree of filling of the polymer carboxyl groups with transition metal ions quenching the luminescence. The equilibrium stability constant of the formed macromolecular metal complex in organic media can be quantitatively estimated from the quenching effect using the relationships that follow from the law of mass action. The formation and stability of Cu2+ and Ni2+ complexes with polymethacrylic acid in protic (methanol, ethanol) and aprotic (dimethylformamide) solvents at low polymer concentrations (0.4–0.02 mg mL–1) were studied using the quenching effect. In methanol, in contrast to ethanol and dimethylformamide, two mechanisms of binding of transition metal ions with different equilibrium stability constants of the complexes (\({K_{{1^{st}}}}\) > 3 × 109 and \({K_{{2^{st}}}}\) ≈ 106–104) were revealed. The infl uence exerted on the stability of the complexes and on the complexation mechanism by the nature and acidity of the organic solvent, polymer concentration, kind of the transition metal ion quenching the luminescence, and NaOH and HCl additions was studied. The results obtained demonstrate the efficiency of the luminescence method used and prospects for its further use for studying polymer systems containing transition metal ions in organic solvents.  相似文献   

4.
Measurements have been made of the binding of divalent metal ions, Cu2+, Ni2+, Co2+, and Zn2+ ions, by polyethylenimine (PEI) and its acetyl or alkyl derivatives by the equilibriumdialysis technique. These metal ions, in particular the Cu2+ ion, exhibited tremendously remarkable binding affinity toward PEI. The extent of complexation of the polymer with the metal ions was decreased markedly by acetylation or alkylation of the polymer. PEI with no primary amine showed an appreciable decrease in its affinity for the metal ion. These results indicate the participation of the primary amine of the polymer in the formation of the complex. A cooperative binding isotherm was observed in PEI–metal ion complex formation, suggesting swelling or conformational change of the polymer induced by this coordination process. Binding of the Cu2+ ion by PEI was found to be essentially independent of temperature over the range 5–35°C.  相似文献   

5.
Polymers were prepared by the condensation of 2, 4-dihydroxybenzaldehydeoxime (2, 4-DBO) and formaldehyde (F) in the presence of oxalic acid as catalyst with varying molar ratios of reacting monomers. Polymers were characterized by their IR spectra, elemental analyses, TGA and Mn as determined by vapour pressure osmometry as well as by non-aqueous conductometric titrations. Viscosity measurements of the solutions of polymer samples were carried out in dimethylformamide. Chelation ion-exchange properties have also been studied employing the batch equilibration method. This method involved the measurement of distribution of a given metal between the polymer sample and a solution containing metal ions. The study was carried out over a wide pH range and in media of various ionic strengths. The polymer showed a higher selectivity for UO 2 2+ and Fe3+ ions than for Cu2+, Ni2+, Co2+ and Mn2+ ions.  相似文献   

6.
Transparent SiO2-Al2O3-NaF-YF3 bulk nano-composites triply doped with Ho3+, Tm3+ and Yb3+ were fabricated by melt-quenching and subsequent heating. X-ray diffraction and transmission electron microscopy measurements demonstrated the homogeneous precipitation of the β-YF3 crystals with mean size of 20 nm among the glass matrix, and rare earth ions were found to partition into these nano-crystals. Under single 976 nm laser excitation, intense red, green and blue upconversion emissions were simultaneously observed owing to the successive energy transfer from Yb3+ to Ho3+ or Tm3+. Various colors of luminescence, including bright perfect white light, can be easily tuned by adjusting the concentrations of the rare earth ions in the material. The overall energy efficiency of the white-light upconversion was estimated to be about 0.2%.  相似文献   

7.
Alginic acid (AA) is a natural polysaccharide derived from brown algae. Naturally AA is present in cellular wall forming insoluble complexes with ions as calcium, magnesium, and sodium. This polymer is composed of uronic acids as d-manuronic acid and l-guloronic acid (units differing in C5 configuration) which are disposed in blocks or alternating on principal chain due its spatial configuration. In its structure only hydroxy and carboxylic acid are present, with a pKa alginic acid = 3.45. At pH = 4.3 this polymer is completely soluble in water. Metal ion retention was evaluated using liquid-phase polymer-based retention (LPR) technique elution method, and metal ions studied were Ag+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ at different pH and filtration factor. A high efficiency for all metal ions at all pH was reveled with a maximum at pH = 4.5 of 100% of majority of metal ions. To evaluate the maximum retention capacity (MRC) of AA, LPR technique concentration method was used. Metal ion/polymer ratio from 48 to 325 mg/g for Zn2+ and Ag+ were studied, respectively. Homopolymer and polymer-metal ion complexes were characterized using FT-IR, Far-IR spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis. FT-IR revealed relevant shifts between AA and PMC, which involve carboxylic acid, hydroxy, and ether groups. DLS shows non-pH-dependent sizes of alginic acid-silver complexes.  相似文献   

8.
Ability of aroylhydrazones to change conformation upon interaction with light makes them promising candidates for molecular switches. Isomerization can be controlled through complexation with selected metal ions which bind with different affinity. N′‐[1‐(2‐hydroxyphenyl)ethyliden]iso‐nicotinoylhydrazide (HAPI) is an example of a dual‐wavelenght photoswitching molecule, whose complexation with metal ions was recently experimentally investigated (Franks et al. J. Inorg. Chem. 2014, 53, 1397). In this contribution, complexes between HAPI and K+, Ca2+, Mn2+, Fe2+, Fe3+, Cu+, Cu2+, and Zn2+ ions were investigated using Density Functional Theory, Natural Bond Order analysis, and Quantum Theory of Atoms in Molecules. The most important parameters that determine complex stability are found to be ion radius and charge transferred from ligands to the ion: smaller ion radii and larger CT values characterize formation of more stable complexes. Our results explain experimentally observed effect of different metal ions on photoisomerization through determination of metal ion affinity (MIA): photoisomerization is inhibited if MIA exceeds 100 kcal/mol; for MIA between 50 and 100 kcal/mol excess of metal ions prevents isomerization, whereas in case of MIA below 50 kcal/mol metal ions have no influence on light–HAPI interaction. © 2015 Wiley Periodicals, Inc.  相似文献   

9.
Lanthanide(III) luminescent hybrid materials based on the layered hectorite have been successfully prepared, showing tunable emission colors as well as white light by varying the molar ratio between Eu3+ and Tb3+.  相似文献   

10.
We demonstrate synthesis of water insoluble, novel copolymer PA1 from condensation of glyoxal dihydrazone and glyoxal dihydrazone bis(dithiocarbamate) monomers having high capacity to remove metal ions from aqueous solution. The presence of a high atomic percentage of nitrogen and sulfur atoms in PA1 leads to strong ligating ability with metal ions. The monomers and the polymer have been characterized by FTIR, UV–Visible spectroscopy, CHNS elemental analysis, NMR, MALDI-MS, and TG/DTA. As a proof of concept, the PA1 is tested for its ability to remove heavy metal ions Cu2+, Co2+, Fe2+, Ni2+, Mn2+, and CrO 7 2? from aqueous solutions. PA1 efficiently removed metals ions from the metal solutions. The highest absorption ability has been observed toward the iron salts where 0.969 g metal salt is absorbed by 1 g polymer. This study has implication for inexpensive and efficient polymer for purification of water.  相似文献   

11.
In this study, a carbon paste electrode modified with a novel 1-(3-aminopropyl) imidazole functionalised crosslinked chlorosulfonated poly(styrene)-divinyl benzene polymer was used for selective and sensitive determination of the trace amounts of Pb2+, Cu2+ and Hg2+ ions by square wave anodic stripping voltammetry. The effect of some parameters such as paste composition, pH, preconcentration time, reduction potential and time, type of supporting electrolyte and potential scan rate on the determination of metal ions were investigated to find the optimal conditions. The effective open-circuit accumulation of the studied metal ions was succeeded only by the modification of the carbon paste electrode with functional polymer. For 6 min open-circuit preconcentration, the detection limit of Pb2+, Cu2+ and Hg2+ was found to be 5, 9 and 14 µgL?1, respectively at 100 mVs?1. The results confirmed that the lower concentration levels of these trace metal ions can be determined with the increase of preconcentration time and/or potential scan rate. Good detection limits and large dynamic concentration ranges were also obtained for their binary and ternary mixtures. The optimised method was successively applied to determine the concentration of Pb2+, Cu2+ ions in the tap water sample and Cu2+ ion in the waste water sample in the presence of possible interfering species (RSD<1%, recoveries 96–110% for 4 min preconcentration).  相似文献   

12.
Terpolymers prepared by condensation of o cresol and urea with formaldehyde in presence of acid catalyst (2 M HCl) proved to be selective chelating ion exchange resins for certain metal ions. The molecular weights of the synthesised terpolymers were determined by GPC Technique. TGA analysis was employed to study the thermal stability and the kinetic data like activation energy of the terpolymer resins. Chelation ion exchange properties of these terpolymers were studied for Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+ and Cd2+ ions. A batch equilibrium method was employed in the study of the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer samples. The study was carried out over a wide pH range and in media of various ionic strengths.  相似文献   

13.
Four new three‐dimensional isostructural lanthanide–cadmium metal–organic frameworks (Ln–Cd MOFs), [LnCd2(imdc)2(Ac)(H2O)2]?H2O (Ln=Pr ( 1 ), Eu ( 2 ), Gd ( 3 ), and Tb ( 4 ); H3imdc=4,5‐imidazoledicarboxylic acid; Ac=acetate), have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, inductively coupled plasma (ICP) analysis, and X‐ray diffraction. Single‐crystal X‐ray diffraction shows that two LnIII ions are surrounded by four CdII ions to form a heteronuclear building block. The blocks are further linked to form 3D Ln–Cd MOFs by the bridging imdc3? ligand. Furthermore, the left‐ and right‐handed helices array alternatively in the lattice. Eu–Cd and Tb–Cd MOFs can emit characteristic red light with the EuIII ion and green light with the TbIII ion, respectively, while both Gd–Cd and Pr–Cd MOFs generate blue emission when they are excited. Different concentrations of Eu3+ and Tb3+ ions were co‐doped into Gd–Cd/Pr–Cd MOFs, and tunable luminescence from yellow to white was achieved. White‐light emission was obtained successfully by adjusting the excitation wavelength or the co‐doping ratio of the co‐doped Gd–Cd and Pr–Cd MOFs. These results show that the relative emission intensity of white light for Gd–Cd:Eu3+,Tb3+ MOFs is stronger than that of Pr–Cd:Eu3+,Tb3+ MOFs, which implies that the Gd complex is a better matrix than the Pr complex to obtain white‐light emission materials.  相似文献   

14.
In this paper, we report on the absorption and photoluminescence properties of Tm3+/Dy3+ ions co-doped oxyfluoride germanate glasses for white light emission. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of the host glass have been carried out to confirm its structure and thermal stability. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4 and Ω6) have been evaluated for Tm3+ and Dy3+ ions. A combination of blue, yellow and red emissions has emerged in these glasses, which allows the observation of bright white light when the glasses are excited by the ultraviolet light. The white light luminescence colour could be changed by varying the excitation wavelength. Also, various colours of luminescence, including white light, can be easily tuned by adjusting the concentrations of Tm3+ or Dy3+ ions in the co-doped glasses. Concentration quenching effect was also investigated and possible energy transfer mechanism from Dy3+→Tm3+ ions was explained which is also confirmed by the decay lifetime measurements.  相似文献   

15.
The effect of quaternized poly(4-vinyl pyridine)(QPVP) on the α,β-elimination of series catalyzed to pyridoxall (PL) or pyridoxal phosphate (PLP) and metla ions was investigated. In PLP-Al3+ and PLP-Fe3+ systems QPVP showed simulation of about forefold; this stimulation was reduced in the presence of 0.5 M KCI. The catalytic activities of PL-Al3+ and PL-Fe3+ were lower compared to the corresponding PLP systems; stimulation by QPVP was also seen, through the extent of stimulation was smaller. The contribution of the electrostatic force between the polymer and the metal complex of the Schiff base was suggested to account for the stimulation. The pyridine moiety on the partialy quaternized PVP did not seen toparticpate in the catalysis. In PLP-Cu2+, PL-Cu2+, and PLP-VO2+ systems, however, QPVP showed marked inhibition. This inhibition by QPVP was also mitigated in the presence of 0.5 M KCl.  相似文献   

16.
We have synthesized a new probe 5-((anthracen-9-ylmethylene) amino)quinolin-10-ol (ANQ) based on anthracene platform. The probe was tested for its sensing behavior toward heavy metal ions Hg2+, Pb2+, light metal Al3+ ion, alkali, alkaline earth, and transition metal ions by UV–visible and fluorescent techniques in ACN/H2O mixture buffered with HEPES (pH 7.4). It shows high selectivity toward sensing Pb2+/Al3+ metal ions. Importantly, 10-fold and 5- fold fluorescence enhancement at 429 nm was observed for probe upon complexation with Pb2+ and Al3+ ions, respectively. This fluorescence enhancement is attributable to the prevention of photoinduced electron transfer. The photonic studies indicate that the probe can be adopted as a sensitive fluorescent chemosensor for Pb2+ and Al3+ ions.  相似文献   

17.
Abstract

The behaviors of heavier rare earth metal ions in bulk liquid membrane transport systems were examined for Gd3+, Tb3+, Dy3, Ho3+, Er3+, Tm3, Yb3+ and Lu3+ ions. The liquid membrane transport system was constructed by aq. HCl/CHCl3 containing Di (2-ethylhexyl) phosphoric acid/aq. HCl. The optimum concentration of HCl in the aqueous phase with respect to the rate of transport for these ions increased with the atomic number of the rare earth elements. This trend of transport behaviors was on the same line observed for lighter rare earth ions in the preceding work. Difference in the rate of transport can be used for selective liquid membrane transport of several sets of combination with these ions.  相似文献   

18.
In the present work, ion-imprinted interpenetrating polymer network (IPN) gels were prepared by free radical/cationic hybrid polymerisation of acrylamide (AAm) and 1,4-butanediol vinyl ether (BVE). These gels were respectively used for separation of Cu2+, Ni2+ and Zn2+ ions in natural water samples. Experimental conditions for effective adsorption of metal ions were optimised with respect to different experimental parameters by column procedures in detail. The optimum pH value for the adsorption of Cu2+, Ni2+ and Zn2+ ions on these sorbents was 6.0. Complete elution of the adsorbed metal ions from the sorbent was carried out using 1.0 mol/L of HCl solution. The optimum sample flow rate and eluent flow rate were, respectively, 1.0 and 0.3 mL/min. Common coexisting ions did not interfere with the separation and determination of the target ions. The accuracy of the proposed method was validated by analysis of the standard reference material (GBW 08301, river sediment). The measured contents of metal ions in the reference material were in good agreement with the certified values. The presented method was successfully applied for the determination of Cu2+, Ni2+ and Zn2+ ions in three different water samples (well water, seawater and waste water).  相似文献   

19.
A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu3+, Tb3+, Ce3+, Y3+, Zn2+, Cd2+, Cu2+) exchanged zeolite, rare‐earth ion (Eu3+, Tb3+, Ce3+) exchanged zeolite modified with Y3+ and rare‐earth ion (Eu3+, Tb3+, Ce3+) exchanged zeolite modified with Zn2+ are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare‐earth ion broadens the application of zeolite as a luminescent host. The Eu3+ ion exchanged zeolite shows white light luminescence with a great application value and Ce3+ exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite.  相似文献   

20.
In the present study, a novel p-phenylcarboxylic acid BODIPY ( L ) immobilized MCM-41 based solid chemosensor material L-propylsilyl@MCM-41 ( MS4 ) was developed to detect multiple metal ions in a pure aqueous medium. The synthesized solid chemosensor material MS4 shows high sensitivity and removal ability towards trivalent (Al3+, Cr3+) and divalent (Cu2+, Hg2+) metal ions. The emission intensity of MS4 enhanced multifold selectively in the presence of trivalent (Al3+, Cr3+) metal ions and shows quenching in the presence of divalent (Cu2+, Hg2+) metal ions. The limit of detection was calculated to be in the nanomolar range with Al3+, Cr3+, Cu2+, and Hg2+ metal ions in the aqueous medium. The spectroscopic and analytical results suggest that MS4 selectively binds with Al3+ and Cr3+ through −NH functionality and with Hg2+ and Cu2+ through −COOH functionality of p-phenylcarboxylic acid BODIPY ( L ). Further, MS4 selectively removes Al3+, Cr3+, Cu2+, and Hg2+ metal ions from the aqueous media with removal efficiency of 97.28 %, 96.34 %, 87.19 %, and 95.63 %, respectively. No noticeable change in the concentration was observed for other metal ions. The recycling potential of MS4 was evaluated using EDTA for up to seven cycles with no significant reduction in sensing capability.  相似文献   

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