Displacement of Cu(II) by Ag(I) in solvated metal sulfides. A DFT and AIM computational study

The substitution of Cu2+ by Ag+ in hydrated CuIIS and (CuII)3S3 was modeled computationally by density functional theory quantum theory of atoms in molecules, and solvent field methods. The coordination, first-shell and partly second-shell molecular structures, and thermochemical data for solvated Cu2+, Ag+, CuIIS, (CuII)3S3, AgCu2S3 and their reactions were obtained. The thermochemical data showed that displacement of Cu2+ and Cu+ from CuIIS and (CuII)3S3 by Ag+, while unfavorable in the gas phase, is facilitated in an aqueous environment. Several covalently bonded species were examined as intermediates in the substitution reactions.     

Does metal ion complexation make radical clocks run fast?

Ab initio molecular orbital and density functional calculations at the CBS-RAD(QCISD,B3-LYP) level for Li+ and at B3LYP for Na+, K+, Cu+,and Ag+ reveal that the barrier to ring-closure of the 1-hexen-6-yl ("Delta(5)-hexenyl") radical to the cyclopentylmethyl radical, a so-called radical clock reaction, is decreased very significantly by complexation of the double bond to metal cations. This barrier lowering should occur on complexation with many metal ions, as shown by calculations on all of the monovalent ions listed above. Additional density functional calculations including explicit solvation of the model system complexed to the lithium ion with tetrahydrofuran suggest that the effect found is not limited to the gas phase but may also be significant in experimental radical clock reactions in solution, even for lithium.     

Bonding analyses, formation energies, and vibrational properties of M-R2dtc complexes (M=Ag(I), Ni(II), Cu(II), or Zn(II))

Detailed theoretical studies based on density functional theory (DFT)/B3LYP calculations of dimethyl- and diethyldithiocarbamate complexes of Ni(II), Cu(II), Zn(II), and Ag(I) are performed to characterize the metal-ligand bonding type as well as the metal-ligand bonding strength depending on the metal and the dialkyl substituent. The metal-ligand interactions in the studied complexes are investigated by means of charge decomposition analysis, energy partitioning analysis (EPA), and natural bond orbital analysis. According to the EPA calculations, the electrostatic attraction is the dominant contribution to the M-S2(R2dtc) (dtc=dithiocarbamate) bonding. The electrostatic and the orbital energies follow the order of the total binding energy, and hence both contributions are responsible for the binding energy order of M(R2dtc)2 complexes. The stability of the M(R2dtc)2 complexes is estimated by means of calculated formation reaction energies in the gas phase and solution, and it decreases in the order Ni(R2dtc)2>Cu(R2dtc)2>Zn(R2dtc)2. Larger formation reaction energies are found for M(Et2dtc)2 than for M(Me2dtc)2 complexes. The calculations predict stabilization of M(II)(R2dtc)2 complexes going from the gas phase to a polar solvent and destabilization of the bidentate AgR2dtc complex in a polar solvent. Gas-phase frequency calculations of all possible bonding types, symmetrical, asymmetrical, and uni- and bidentate, predict one band due to the nu(CS) IR absorption, and therefore the number of the bands in the 1060-920 cm(-1) region could not be used to discern the metal-ligand bonding type. Periodic DFT frequency calculations for Cu(Et2dtc)2 reveal that the splitting observed in the solid-state spectra of the complexes arises from the nonplanar MS4 fragment and intermolecular contacts but not from asymmetrical bonding. The calculations suggest that the important vibrational characteristic that can be used to discern uni- and bidentate bonding is the Raman activity of the nu(CS) band: It is very high for the unidentate dtc bonding (nu(C=S)) and low for the bidentate bonding (nuas(CS)).     

Density functional theory-based prediction of some aqueous-phase chemistry of superheavy element 111. Roentgenium(I) is the "softest" metal ion

A previous approach (Hancock, R. D.; Bartolotti, L. J. Inorg. Chem. 2005, 44, 7175) using DFT calculations to predict log K1 (formation constant) values for complexes of NH3 in aqueous solution was used to examine the solution chemistry of Rg(I) (element 111), which is a congener of Cu(I), Ag(I), and Au(I) in Group 1B. Rg(I) has as its most stable presently known isotope a t(1/2) of 3.6 s, so that its solution chemistry is not easily accessible. LFER (Linear free energy relationships) were established between DeltaE(g) calculated by DFT for the formation of monoamine complexes from the aquo ions in the gas phase, and DeltaG(aq) for the formation of the corresponding complexes in aqueous solution. For M2+, M3+, and M4+ ions, the gas-phase reaction was [M(H2O)6]n+(g) + NH3(g) = [M(H2O)5NH3]n+(g) + H2O(g) (1), while for M+ ions, the reaction was [M(H2O)2]+(g) + NH3(g) = [M(H2O)NH3]+(g) + H2O(g) (2). A value for DeltaG(aq) and for DeltaE for the formation of M = Cu2+ in reaction 1, not obtained previously, was calculated by DFT and shown to correlate well with the LFER obtained previously for other M2+ ions, supporting the LFER approach used here. The simpler use of DeltaE values instead of DeltaG(aq) values calculated by DFT for formation of monoamine complexes in the gas phase leads to LFER as good as the DeltaG-based correlations. Values of DeltaE were calculated by DFT to construct LFER with M+ = H+, and the Group 1B metal ions Cu+, Ag+, Au+, and Rg+, and with L = NH3, H2S, and PH3 in reaction 3: [M(H2O)2]+(g) + L(g) = [M(H2O)L]+g) + H2O(g) (3). Correlations involving DeltaE calculated by DMol3 for H+, Cu+, Ag+, and Au+ could reliably be used to construct LFER and estimate unknown log K1 values for Rg(I) complexes of NH3, PH3, and H2S calculated using the ADF (Amsterdam Density Functional) code. Log K1 values for Rg(I) complexes are predicted that suggest the Rg(I) ion to be a very strong Lewis acid that is extremely "soft" in the Pearson hard and soft acids and bases sense.     

Electronic structure and solvation of copper and silver ions: a theoretical picture of a model aqueous redox reaction

Electronic states and solvation of Cu and Ag aqua ions are investigated by comparing the Cu(2+) + e(-)--> Cu(+) and Ag(2+) + e(-)--> Ag(+) redox reactions using density functional-based computational methods. The coordination number of aqueous Cu(2+) is found to fluctuate between 5 and 6 and reduces to 2 for Cu(+), which forms a tightly bound linear dihydrate. Reduction of Ag(2+) changes the coordination number from 5 to 4. The energetics of the oxidation reactions is analyzed by comparing vertical ionization potentials, relaxation energies, and vertical electron affinities. The model is validated by a computation of the free energy of the full redox reaction Ag(2+) + Cu(+) --> Ag(+) + Cu(2+). Investigation of the one-electron states shows that the redox active frontier orbitals are confined to the energy gap between occupied and empty states of the pure solvent and localized on the metal ion hydration complex. The effect of solvent fluctuations on the electronic states is highlighted in a computation of the UV absorption spectrum of Cu(+) and Ag(+).     

A density functional theory study of molecular and dissociative adsorption of H2 on active sites in mordenite

Adsorption and chemisorption of H2 in mordenite is studied using ab initio density functional theory (DFT) calculations. The geometries of the adsorption complex, the adsorption energies, stretching frequencies, and the capacity to dissociate the adsorbed molecule are compared for different active sites. The active centers include a Br?nsted acid site, a three-coordinated surface Al site, and Lewis sites formed by extraframework cations: Na+, Cu+, Ag+, Zn2+, Cu2+, Ga3+, and Al3+. Adsorption properties of cations are compared for a location of the cation in the five-membered ring. This location differs from the location in the six-membered ring observed for hydrated cations. The five-membered ring, however, represents a stable location of the bare cation. In this position any cation exhibits higher reactivity compared with the location in the six-membered ring and is well accessible by molecules adsorbed in the main channel of the zeolite. Calculated adsorption energies range from 4 to 87 kJ/mol, depending on electronegativity and ionic radius of the cation and the stability of the cation-zeolite complex. The largest adsorption energy is observed for Cu+ and the lowest for Al3+ integrated into the interstitial site of the zeolite framework. A linear dependence is observed between the stretching frequency and the bond length of the adsorbed H2 molecule. The capacity of the metal-exchanged zeolite to dissociate the H2 molecule does not correlate with the adsorption energy. Dissociation is not possible on single Cu+ cation. The best performance is observed for the Ga3+, Zn2+, and Al3+ extraframework cations, in good agreement with experimental data.     

Photocontrollable cation extraction with crowned oligo(spirobenzopyran)s.

The photoinduced changes of metal-ion extractability of crown ether derivatives bearing three or four spirobenzopyran moieties and their analogues were studied using 1,2-dichloroethane as the organic solvent. Under dark conditions, these compounds extracted Cu2+, Ag+, and Pb2+ with their counteranions from the aqueous phase to the organic phase. The extraction equilibrium constants of the photochromic crown ether derivatives for Cu2+ and Ag+ were determined successfully. Under UV-light irradiation conditions, the extraction of Cu2+ by crowned tris(spirobenzopyran) was enhanced, while that of Ag+ was suppressed. During the competitive metal-ion extraction of crowned oligo(spirobenzopyran)s between Cu2+ and Ag+, the metal-ion selectivity was reversed explicitly by photoirradiation.     

Factors governing the metal coordination number in isolated group IA and IIA metal hydrates

Many of the group IA and IIA metal ions, such as Na+, K+, Mg2+, and Ca2+, play crucial roles in biological functions. Previous theoretical studies generally focus on the number of water molecules bound to a particular (as opposed to all) alkali or alkaline earth cations and could not establish a single preferred CN for the heavier alkali and alkaline earth ion-water complexes. Crystal structures of hydrated Na+, K+, and Rb+ also cannot establish the preferred number of inner-shell water molecules bound to these cations. Consequently, it is unclear if the gas-phase CNs of group IA metal hydrates increase with increasing ion size, as observed for the group IIA series from the Cambridge Structural Database, and if the same factors govern the gas-phase CNs of both group IA and IIA ion-water complexes. Thus, in this work, we determine the number of water molecules directly bound to the series of alkali (Li+, Na+, K+, and Rb+) and alkaline earth (Be2+, Mg2+, Ca2+, Sr2+, and Ba2+) metal ions in the gas phase by computing the free energy for forming an isolated metal-aqua complex as a function of the number of water molecules at 298 K. The preferred gas-phase CNs of group IA hydrates appear insensitive to the ion size; they are all 4, except for Rb+, where a CN of 6 seems as likely. In contrast, the preferred gas-phase CNs of the group IIA dications increase with increasing ion size; they are 4 for Be2+, 6 for Mg2+ and Ca2+, and 7 for Sr2+ and Ba2+. An entropic penalty disfavors a gas-phase CN greater than 4 for group IA hydrates, but it does not dictate the gas-phase CNs of group IIA hydrates. Instead, interactions between the metal ion and first-shell water molecules and between first-shell and second-shell water molecules govern the preferred gas-phase CNs of the group IIA metal hydrates.     

Effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water coordination on the structure of glycine and zwitterionic glycine

Interactions between metal ions and amino acids are common both in solution and in the gas phase. Here, the effect of metal ions and water on the structure of glycine is examined. The effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water on structures of Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (m = 0, 2, 5) complexes have been determined theoretically by employing the hybrid B3LYP exchange-correlation functional and using extended basis sets. Selected calculations were carried out also by means of CBS-QB3 model chemistry. The interaction enthalpies, entropies, and Gibbs energies of eight complexes Gly.Mn+ (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) were determined at the B3LYP density functional level of theory. The computed Gibbs energies DeltaG degrees are negative and span a rather broad energy interval (from -90 to -1100 kJ mol(-1)), meaning that the ions studied form strong complexes. The largest interaction Gibbs energy (-1076 kJ mol(-1)) was computed for the NiGly2+ complex. Calculations of the molecular structure and relative stability of the Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+; m = 0, 2, and 5) systems indicate that in the complexes with monovalent metal cations the most stable species are the NO coordinated metal cations in non-zwitterionic glycine. Divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ prefer coordination via the OO bifurcated bonds of the zwitterionic glycine. Stepwise addition of two and five water molecules leads to considerable changes in the relative stability of the hydrated species. Addition of two water molecules at the metal ion in both Gly.Mn+ and GlyZwitt.Mn+ complexes reduces the relative stability of metallic complexes of glycine. For Mn+ = Li+ or Na+, the addition of five water molecules does not change the relative order of stability. In the Gly.K+ complex, the solvation shell of water molecules around K+ ion has, because of the larger size of the potassium cation, a different structure with a reduced number of hydrogen-bonded contacts. This results in a net preference (by 10.3 kJ mol(-1)) of the GlyZwitt.K+H2O5 system. Addition of five water molecules to the glycine complexes containing divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ results in a net preference for non-zwitterionic glycine species. The computed relative Gibbs energies are quite high (-10 to -38 kJ mol(-1)), and the NO coordination is preferred in the Gly.Mn+(H2O)5 (Mn+ = Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) complexes over the OO coordination.     

Density functional theory-based prediction of the formation constants of complexes of ammonia in aqueous solution: indications of the role of relativistic effects in the solution chemistry of gold(I)

A prediction of the formation constants (log K1) for complexes of metal ions with a single NH3 ligand in aqueous solution, using quantum mechanical calculations, is reported. DeltaG values at 298 K in the gas phase for eq 1 (DeltaG(DFT)) were calculated for 34 metal ions using density functional theory (DFT), with the expectation that these would correlate with the free energy of complex formation in aqueous solution (DeltaG(aq)). [M(H2O)6]n+(g) + NH(3)(g) = [M(H2O)5NH3]n+(g) + H2O(g) (eq 1). The DeltaG(aq) values include the effects of complex changes in solvation on complex formation, which are not included in eq 1. It was anticipated that such changes in solvation would be constant or vary systematically with changes in the log K(1) value for different metal ions; therefore, simple correlations between DeltaG(DFT) and DeltaG(aq) were sought. The bulk of the log K1(NH3) values used to calculate DeltaG(aq) were not experimental, but estimated previously (Hancock 1978, 1980) from a variety of empirical correlations. Separate linear correlations between DeltaG(DFT) and DeltaG(aq) for metal ions of different charges (M2+, M3+, and M4+) were found. In plots of DeltaG(DFT) versus DeltaG(aq), the slopes ranged from 2.201 for M2+ ions down to 1.076 for M4+ ions, with intercepts increasing from M2+ to M4+ ions. Two separate correlations occurred for the M3+ ions, which appeared to correspond to small metal ions with a coordination number (CN) of 6 and to large metal ions with a higher CN in the vicinity of 7-9. The good correlation coefficients (R) in the range of 0.97-0.99 for all these separate correlations suggest that the approach used here may be the basis for future predictions of aqueous phase chemistry that would otherwise be experimentally inaccessible. Thus, the log K1(NH3) value for the transuranic Lr3+, which has a half-life of 3.6 h in its most stable isotope, is predicted to be 1.46. These calculations should also lead to a greater insight into the factors governing complex formation in aqueous solution. All of the above DFT calculations involved corrections for scalar relativistic effects (RE). Au has been described (Koltsoyannis 1997) as a "relativistic element". The chief effect of RE for group 11 ions is to favor linear coordination geometry and greatly increase covalence in the M-L bond. The correlation for M+ ions (H+, Cu+, Ag+, Au+) involved the preferred linear coordination of the [M(H2O)2]+ complexes, so that the DFT calculations of DeltaG for the gas-phase reaction in eq 2 were carried out for M = H+, Cu+, Ag+, and Au+. [M(H2O)2]+(g) + NH3(g) = [M(H2O)NH3]+(g) + H2O(g) (eq 2). Additional DFT calculations for eq 2 were carried out omitting corrections for RE. These indicated, in the absence of RE, virtually no change in the log K1(NH3) value for H+, a small decrease for Cu+, and a larger decrease for Ag+. There would, however, be a very large decrease in the log K1(NH3) value for Au(I) from 9.8 (RE included) to 1.6 (RE omitted). These results suggest that much of "soft" acid behavior in aqueous solution in the hard and soft acid-base classification of Pearson may be the result of RE in the elements close to Au in the periodic table.     

液膜分离富集金与测定微量金

提出采用乳状液膜体系分离、富集金。该体系包括协同流动载体（TBP和PMBP），表面活性剂（SPAN80），膜的增强剂（液体石蜡），膜溶剂（煤油）和内相（1％质量分数的NaOH水溶液）。实验结果表明，金的迁移率达90．5％以上。此条件下，许多共存金属高于如∑RE3+、Ag2+、Pd2+、Pt4+、Rh3+、Cu2+、Fe3+、Al3+、Pb2+、Zn2+、Mo6+、W6+、Mn2+、Sn4+、Te4+、Se4+、Ca2+和Mg2+等不被迁移，只有金能与这些金属离子得到满意的分离。该法已应用于测定提金溶液和氰化物没出贵金属溶液中的微量金，相对标准偏差为1．3％－3．9％。     

N-芳基香豆素甲基酮缩氨基硫脲对Cu2+的选择性比色识别

设计合成了2种新型N-芳基香豆素甲基酮缩氨基硫脲受体分子S1和S2, 利用紫外-可见(UV-Vis)吸收光谱考察了其对Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Zn2+, Pb2+, Cd2+, Ni2+, Cr3+和Mg2+等阳离子的识别作用. 结果表明, 当加入Cu2+时, 溶液颜色立刻由无色变为黄色, 而加入其它阳离子则无变化, 从而实现了对Cu2+的裸眼检测, 具有专一选择性比色识别效果. 通过计算可知, 受体分子S2对Cu2+的络合常数大于S1, 且主客体间形成1: 1的配合物. 受体分子S2对Cu2+的检出限为2.0×10-7 mol/L, 稳定常数Ks=1.02×105 L/mol. 另外, 在EDTA存在时, 配合物可以释放出Cu2+, 与EDTA结合, 表现出对Cu2+的"off-on"模式.     

Activation of methane by gold cations: guided ion beam and theoretical studies

The potential energy surface for activation of methane by the third-row transition metal cation, Au+, is studied experimentally by examining the kinetic energy dependence of this reaction using guided ion beam tandem mass spectrometry. A flow tube ion source produces Au+ primarily in its 1S0 (5d10) electronic ground state level but with some 3D (and perhaps higher lying) excited states that can be completely removed by a suitable quenching gas (N2O). Au+ (1S0) reacts with methane by endothermic dehydrogenation to form AuCH2+ as well as C-H bond cleavage to yield AuH+ and AuCH3+. The kinetic energy dependences of the cross sections for these endothermic reactions are analyzed to give 0 K bond dissociation energies (in eV) of D0(Au+ - CH2) = 3.70 +/- 0.07 and D0(Au+ -CH3) = 2.17 +/- 0.24. Ab initio calculations at the B3LYPHW + /6-311++G(3df,3p) level performed here show good agreement with the experimental bond energies and previous theoretical values available. Theory also provides the electronic structures of the product species as well as intermediates and transition states along the reactive potential energy surface. Surprisingly, the dehydrogenation reaction does not appear to involve an oxidative addition mechanism. We also compare this third-row transition metal system with the first-row and second-row congeners, Cu+ and Ag+. Differences in thermochemistry can be explained by the lanthanide contraction and relativistic effects that alter the relative size of the valence s and d orbitals.     

Theoretical studies of UO2(H2O)n(2+), NpO2(H2O)n(+), and PuO2(H2O)n(2+) complexes (n=4-6) in aqueous solution and gas phase

Extensive ab initio calculations both in gas phase and solution have been carried out to study the equilibrium structure, vibrational frequencies, and bonding characteristics of various actinyl (UO2(2+), NpO2(+), and PuO2(2+)) and their hydrated forms, AnO2(H2O)n(z+) (n=4, 5, and 6). Bulk solvent effects were studied using a continuum method. The geometries were fully optimized at the coupled-cluster singles + doubles (CCSD), density-functional theory (DFT), and M?ller-Plesset (MP2) level of theories. In addition vibrational frequencies have been obtained at the CCSD as well as MP2/DFT levels. The results show that both the short-range and long-range solvent effects are important. The combined discrete-continuum model, in which the ionic solute and the solvent molecules in the first and second solvation shells are treated quantum mechanically while the solvent is simulated by a continuum model, can predict accurately the bonding characteristics. Moreover, our values of solvation free energies suggest that five- and six-coordinations are equally preferred for UO2(2+), and five-coordinated species are preferred for NpO2(+) and PuO2(2+). On the basis of combined quantum-chemical and continuum treatments of the hydrated complexes, we are able to determine the optimal cavity radii for the solvation models. The coupled-cluster computations with large basis sets were employed for the vibrational spectra and equilibrium geometries both of which compare quite favorably with experiment. Our most accurate computations reveal that both five- and six-coordination complexes are important for these species.     

Efficient computational methods for accurately predicting reduction potentials of organic molecules

A simple computational approach for predicting ground-state reduction potentials based upon gas phase geometry optimizations at a moderate level of density functional theory followed by single-point energy calculations at higher levels of theory in the gas phase or with polarizable continuum solvent models is described. Energies of the gas phase optimized geometries of the S0 and one-electron-reduced D0 states of 35 planar aromatic organic molecules spanning three distinct families of organic photooxidants are computed in the gas phase as well as well in implicit solvent with IPCM and CPCM solvent models. Correlation of the D0 - S0 energy difference (essentially an electron affinity) with experimental reduction potentials from the literature (in acetonitrile vs SCE) within a single family, or across families when solvent models are used, yield correlations with r(2) values in excess of 0.97 and residuals of about 100 mV or less, without resorting to computationally expensive vibrational calculations or thermodynamic cycles.     

A Theoretical Study of Ene Reactions in Solution: A Solution‐Phase Translational Entropy Model

Several density functional theory (DFT) methods, such as CAM‐B3LYP, M06, ωB97x, and ωB97xD, are used to characterize a range of ene reactions. The Gibbs free energy, activation enthalpy, and entropy are calculated with both the gas‐ and solution‐phase translational entropy; the results obtained from the solution‐phase translational entropies are quite close to the experimental measurements, whereas the gas‐phase translational entropies do not perform well. For ene reactions between the enophile propanedioic acid (2‐oxo‐1,3‐dimethyl ester) and π donors, the two‐solvent‐involved explicit+implicit model can be employed to obtain accurate activation entropies and free‐energy barriers, because the interaction between the carbonyl oxygen atom and the solvent in the transition state is strengthened with the formation of C?C and O?H bonds. In contrast, an implicit solvent model is adequate to calculate activation entropies and free‐energy barriers for the corresponding reactions of the enophile 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione.     

Molecular–Continuum Model for the Cyanide Ion Adsorption from Aqueous Solutions on Copper Metals

Quantum-chemical calculations of the cyanide ion adsorption from aqueous solutions on copper metals are performed for the first time in a combined molecular–continuum model of polar solvent. The calculations use the cluster model of the surface and are carried out by the density functional in the B3LYP version. The effect of the adsorption system's polar dielectric environment is considered in a self-consistent reactive field model, namely, the SCIPCM model. The dielectric cavity is built in SCIPCM self-consistently with the particle's electron density distribution in solution. Calculations show that the CN^– adsorption energy decreases in the sequence Au > Cu > Ag. The calculated energy agrees best with the experimental data when the molecular–continuum model is used, rather than the simpler molecular and continuum models.     

羧甲基二硫代氨基甲酸酯功能化聚氯乙烯树脂的合成及对Ag~+的吸附与选择性能

以聚氯乙烯为大分子骨架,经三乙烯四胺胺化,再与二硫化碳和乙醇钠反应,得到的二硫代氨基羧酸盐改性聚氯乙烯树脂(PV-NS)进一步与氯乙酸钠反应,合成了一种同时舍N,S,O的羧甲基二硫代氨基甲酸酯改性聚氯乙烯树脂(PV-NSO).合成树脂的功能基结构经红外和元素分析确认.对合成树脂的吸附性能研究表明,合成树脂对Ag+、Hg2+、Au<'3+>、Pb2+离子的吸附容量在实验条件下分别达2.058mmol/g、1.514mmol/g,1.125mmol/g和0.415mmol/g,而对Cu2+、Cd2+、Zn2+、Ni2+、Mg2+等离子的吸附容量很小,甚至不吸附.树脂的选择性吸附表明,树脂对Ag+的吸附选择性较好,在有Hg2+、Pb2+、Cd2+、Zn2+、Cu2+或Mg2+共存时,树脂对Ag+的选择性吸附系数分别达4.74、17.33,12.98、∞、7.60和74.14.合成树脂在极性溶剂中的溶胀性能均比在非极性溶剂中好.     

Synthesis and luminescence properties of Ag2S and PbS clusters in zeolite A

Zeolite A provides a suitable environment to host Ag2S and PbS clusters, so that spectroscopic investigations on very small particles are possible. The Ag2S monomer is colorless and shows photoluminescence at 490 nm with a lifetime of 300 micros, while the absorption and luminescence of Ag4S2 and larger clusters are red-shifted. The properties of these Ag2S/zeolite A materials depend on the co-cations. Results for Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, and Sr2+ are reported. Excitation energy transfer between Ag2S and Ag4S2 has been studied in materials containing Ca2+ co-cations. PbS particles can be prepared by the same method as Ag2S in the cavities of zeolite A. The PbS monomers obtained are yellow and show photoluminescence at 570 nm, with a lifetime of 700 ns.