A New Fluorescent Sensor for Transition Metal Ions in Aqueous Solution

Molecularsystemswhichcombinebindingabilityandphotochemicaland/orphotophysicalpropertiesareofgreatinterestfordesigningmoleculardevicesdisplayingphotoactivityfeatures'.Duringthelastdecade,anumberoffluorescentsensorsforcationdetectionhavebeendeveloped'-".Mostofthemoperatesbyaphotoinducedelectrontransfer(PET)mechanism.Inaclassicexample",theuncomplexedsensorisnotfluorescentasthephotoexcitedfluorophoreisdeactivatedbythetTansferofanelectronfromthehighlyreducingproximateteFtiaryaminegroup.Followingm…     

IR Spectroscopic Study of the Interaction of Transition Metal Ions with Hydroxyapatite Modified by Potassium Ferrocyanide

IR spectroscopy was used to study the modification of hydroxyapatite by potassium ferrocyanide and the interaction of transition metal ions with the modified adsorbent. The structural changes of hydroxyapatite upon the adsorption of Zn²⁺ ions were studied by X-ray phase analysis. Potassium ferrocyanide was found to interact with the surface hydroxyl groups of hydroxyapatite through the nitrogen unshared electron pair. Co²⁺, Ni²⁺, and Zn²⁺ ions were found to eliminate outer-sphere K⁺ ions of adsorbed ferrocyanide to give Fe²⁺— CN—M²⁺— NC—Fe²⁺ bridging structures. Zn²⁺ cations additionally eliminate a part of the Ca²⁺ ions from structural positions of hydroxyapatite, which leads to the appearance of a two-phase hydroxyapatite–sholzite system with heterogeneous distribution of the Ca²⁺ ions in the mot her mineral phase, while the Zr²⁺ ions are found in the new sholzite phase.     

Calixarene Complexes with Transition Metal Ions

Selected calixarene complexes with transition metal ions are described showing their syntheses and possible applications, especially in the aspect of the environmental protection.This revised version was published online in July 2005 with a corrected issue number.     

基于过渡金属离子与三联吡啶的配位作用构筑全共轭层-层 自组装超薄功能膜

本文利用所合成的4'-（4''-重氮基）苯基-（2,2':6',2'）-三联吡啶氟硼酸盐（Diazo-tpy）在紫外光照射下的光分解反应特性,实现三联吡啶基团与基片之间形成共轭价键连接,这不仅提高了自组装膜的稳定性,而且降低了载流子在两者之间传输时的阻抗;在此基础上,通过两端含三联吡啶的直线型配体1,4-二-(2,2':6',2'-三联吡啶)基苯（Bi-tpy）与四种过渡金属离子（Mtn+：Pt4+、Ru3+、Rh3+、Pd2+）之间的配位作用,通过层－层自组装制备了全共轭金属－有机自组装超薄功能膜。由紫外-可见光谱跟踪自组装过程证明了自组装过程的成功实现,还分析了金属离子的种类对自组装的影响规律。光电转换测试表明Bi-tpy/Ru3+自组装膜要比Bi-tpy/ Pt4+具有更明显的光电转换性能;同时,由于缺陷与阻抗随层数的增加而增大的原因,在自组装6层时光电流达到最大值。这为我们设计新型光电转换器件提供参考依据。     

过渡金属离子掺杂改性TiO2的光催化性能研究进展

 对近年来利用过渡金属离子掺杂改性TiO2的光催化性能研究进行了综述．分析了掺杂金属离子的种类、掺杂浓度和掺杂制备方式等对TiO2光催化性能的影响,并提出了今后的研究方向．     

Binding Interaction of Captopril with Metal Ions: A Fluorescence Quenching Study

The binding interaction of captopril (CPL) with biologically active metal ions Mg²⁺, Ca²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ was investigated in an aqueous acidic medium by fluorescence spectroscopy. The experimental results showed that the metal ions quenched the intrinsic fluorescence of CPL by forming CPL‐metal complexes. It was found that static quenching was the main reason for the fluorescence quenching. The quenching constant in the case of Cu²⁺ was highest among all quenchers, perhaps due to its high nuclear charge and small size. Quenching of CPL by metal ions follows the order Cu²⁺>Ni²⁺>Co²⁺>Ca²⁺>Zn²⁺>Mn²⁺>Mg²⁺. The quenching constant K_sv, bimolecular quenching constant K_q, binding constant K and the binding sites "n" were determined together with their thermodynamic parameters at 27 and 37°C. The positive entropy change indicated the gain in configurational entropy as a result of chelation. The process of interaction was spontaneous and mainly ΔS‐driven.     

Interaction of Methyl Cysteine and Nitrilotriacetate with Transition Metal Ions

In the present work, sulfur-containing amino acid methyl cysteine was studied from the point of view of their coordinating ability with two metal ions, viz. copper(II) and cobalt(II). Solution equilibria of binary (Cu(II)/Co(II)–methyl cysteine and Cu(II)/Co(II)–nitrilotriacetate (NTA)) complex systems are investigated by paper ionophoresis at 35°C, ionic strength I= 0.1 mol/l. In addition to binary complexes, ternary complexes involving nitrilotriacetate and methyl cysteine were also studied. For studying mixed-ligand complexes, the pH of background electrolyte is brought to 8.5 (this pH value is purposely chosen because amino acid and NTA form very stable complexes much ahead of this pH). The stability constants of complexes (Cu(II)–NTA–methyl cysteine and Co(II)–NTA–methyl cysteine) were found to be 4.48 ± 0.07 and 3.55 ± 0.04 (logKvalues), respectively.     

The Interaction of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with Mixed Donor Macrocycles Containing Pendant Carboxylic Acid Functions

The syntheses of mixed oxygen-nitrogen donor macrocycles incorporating two or three pendant carboxylic acid groups are described. Potentiometric titrations in water (I = 0.1; KNO₃) at 25°C have been used to determine the stability constants for the 1: 1 (metal:ligand) complexes of Co(II). Ni(II), Cu(II), Zn(II), and Cd(II). The constants obtained are compared with the previously determined values for the corresponding complexes of the unsubstituted macrocyclic precursors. The results of these studies indicate that each carboxylate function participates in binding to the central metal. For some metal-ion/ligand systems there is evidence that ring size effects influence the overall stability patterns and that, in such cases, both the ether oxygens as well as the tertiary amines of the macrocyclic rings appear to bind to the metal.     

Minireview: A Caritical Review of the Transition Metal Ions Influence on Peroxyoxalate Chemiluminescence

ABSTRACT

A detailed study and evaluation of the presence of Cr(III), Zn(II) and Pb(II) and various parameters affecting the intensity of the chemiluminescent reaction of TCPO and 2-NPO with hydrogen peroxide in the presence of 3-aminofluoranthene, as the fluorophore, and imidazole (IMI) as catalyst, is presented. Depending on the unprotonated imidazole and fluorophore concentrations, these metal ions enhance the intensity of the fluorophore at pH's higher than 8.0. At pH = 7.0, in the presence of IMI/HIMI⁺ (IMI = 1×10^?2 mol.L^?1), tris(hydroxymethyl)aminomethane or HPO₄ ^2?/H₂PO₄ ^? buffers, no effect of these metal ions was observed. A critical comparison with the data reported in the literature is presented.     

Separation of Selected Transition Metal Ions and Divalent Metal Ions by HPLC Using UV-VIS Detection

Abstract

The use of ethylenediaminetetraacetic acid, disodium salt, (pH 3-5) has been investigated as an eluant for the separation and detection of nanogram levels of selected divalent and trivalent metal ions. The effect of pH and eluant concentration upon the retention times and resolution of the system are given and the ability to alter the eluant characteristics to optimize the chromatographic results in different situations will be discussed. The method is less complicated than the method frequently used for transition metal ion determinations which uses a post-column derivitization reagent. This method is applicable to a wider range of metal ions and provides detection limits which are generally within two orders of magnitude of the post-column derivitization method.     

Hydrogen-Release Reaction of a Complex Transition Metal Hydride with Covalently Bound Hydrogen and Hydride Ions

The hydrogen-release reaction of a complex transition metal hydride, LaMg₂NiH₇, composed of La³⁺, 2×Mg²⁺, [NiH₄]⁴⁻ and 3×H⁻, was studied by thermal analyses, powder X-ray, and neutron diffraction and inelastic neutron scattering. Upon heating, LaMg₂NiH₇ released hydrogen at approximately 567 K and decomposed into LaH₂₋₃ and Mg₂Ni. Before the reaction, covalently bound hydrogen (H^c°^v.) in [NiH₄]⁴⁻ exhibited a larger atomic displacement than H⁻, although a weakening of the chemical bonds around [NiH₄]⁴⁻ and H⁻ was observed. These results indicate the precursor phenomenon of a hydrogen-release reaction, wherein there is a large atomic displacement of H^c°^v. that induces the hydrogen-release reaction rather than H⁻. As an isothermal reaction, LaMg₂NiH₇ formed LaMg₂NiH_2.4 at 503 K in vacuum for 48 h, and LaMg₂NiH_2.4 reacted with hydrogen to reform LaMg₂NiH₇ at 473 K under 1 MPa of H₂ gas pressure for 10 h. These results revealed that LaMg₂NiH₇ exhibited partially reversible hydrogen-release and uptake reactions.     

高度隔离过渡金属催化剂及其烯烃环氧化研究

 介绍了过渡金属杂原子分子筛的骨架杂原子表征、用离子注入法和化学嫁接法制备高度隔离过渡金属催化剂及其催化烯烃环氧化研究的结果．基于共振拉曼原理,用紫外共振拉曼光谱明确鉴别了TS－1,Fe－ZSM－5和V－MCM－41等分子筛中的骨架杂原子．用离子注入法和化学嫁接法制得具有高度隔离过渡金属离子的非杂原子分子筛催化剂．烯烃环氧化反应结果表明,所制得的催化剂显示出优良的催化性能．     

过渡金属与新型硝基酚臂式氮杂18-冠-6配位性能的研究

合成并表征了1,10-二氧-4,7,13,16-四氮杂18-冠-6 (1)母体及其四取代硝基酚臂式衍生物 (2)。在H₂O-DMSO(V/V=1/4)混合溶剂中用UV-Vis光谱法对冠醚2与H⁺、Mn²⁺、Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Cd²⁺和Hg^{2+相似文献}   

Complexing Properties of Phenolic Diazacrown Ethers with Transition and Heavy Metal Ions

The complexation equilibria of the phenolic diazacrown ether derivatives L1–L11 with transition and heavy metal ions (Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Pb²⁺) have been studied in methanol using UV absorption spectrophotometry. A majority of the systems studied formed only ML complexes. Using a ligand with a different position of the substituents on the phenolic side arms (denoted L7) leads to ML₂ formation with most of the metal ions. Every ligand forms very strong ML and ML₂ complexes with Pb²⁺, and, in nearly all cases, only a lower limit could be derived for the stability constant. The stability of the complexes generally increases as the length of the para-substituents on the phenol groups increases. Among the metal ions tested, Zn²⁺ and Hg²⁺ are the least preferred by alkyl and alkoxy derivatives, respectively.     

铜二取代三元杂多化合物的制备、晶体结构和性质

The half Dawson structure complex has been prepared by reaction of Na₂WO₄·2H₂O, Na₂MoO₄·2H₂O and NaH₂PO₄ in water. [TBA]₄H₃[PW₆Mo₄Cu₂O₃₈(H₂O)₂] have been synthesized by reaction of [PW₅Mo₄O₃₄]^9- and Cu²⁺ in water and recrystallized in a mixed acetone/water solvent. They were characterized by elemental analyses, IR spectra and electronic spectra. The crystal structure of [TBA]₄H₃[PW₆Mo₄Cu₂O₃₈(H₂O)₂] has been determined by X-ray structure analysis for the first time, which belongs to trigonal with space group R-3, a=b=c=1.53081 (18) nm, α=β=γ=109.458(17)°, Z=1, D_c=3.141Mg·m^-3, R=0.0780, R_w=0.1480. The sites of the molybdenum, tungsten and copper atoms are disordered over 12 possible locations in the crystal, and the anion has a high symmetry due to the disorder of the molybdenum, tungsten and copper atoms. CCDC: 176656.     

Study of Host-Guest Complexation of Alkaline Earth Metal Ion,Aluminum Ion and Transition Metal Ions with Crown Ethers by Fast Atom Bombardment Mass Spectrometry

Complexations of crown ethers with alkali metal ions have been investigated extensively by FAB mass spectrometry over the past decade, but very little attention has been paid to reactions of crown ethers with other classes of metal ions such as alkaline earth metal ions, transition metal ions and aluminum ions. Although fast atom bombardment ionization mass spectrometry has proven to be a rapid and convenient method to determine the binding interactions of crown ethers with metal ions, problems in reliabilities for quantitative measurements of” binding strength for the host-guest complexes have been described in the literature. Thus, in this paper, applications of FAB/MS for investigating the complexation of crown ethers with various classes of metal ions is discussed. Extensive fragmentations for neutral losses such as C₂H₄O or C₂H₄ molecules from the host-guest complexes could be observed. The reason is attributed to the energetic bombardment processes of FAB occuring in the formation of these complexes. Complexes of cyclen with metal ions also show neutral losses of C₂H₄NH molecules leading to fragment ions. Transition metal ions usually form (Crown + MCl)⁺ type of ions, alkaline earth metal ions can form both (Crown + MCl)⁺ and (Crown + MOH)⁺ type of ions. But for aluminum ions, only (Crown + Al(OH)₂)⁺ type of ions could he observed.     

Thermal Decomposition of Chloromethylated Poly(styrene)-PAN Resin and Its Complexes with Some Transition Metal Ions

The complexes formed by the chemically modified chloromethylated poly(styrene)-PAN (CMPS-PAN) as a resin chelating ion exchanger were characterized by infrared and potentiometry. The thermal degradation of pure CMPS-PAN resin and its complexes with Au³⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺ and Pt⁴⁺ in air atmosphere has been studied using thermal gravimetry (TG) and derivative thermal gravimetry (DTG). The results showed that four different steps accompany the decomposition of CMPS-PAN resin and its complexes with the metal ions. These stages were affected by the presence of the investigated metal ions. The thermal degradation of CMPS-PAN resin in the presence of the ions showed different stability of the resin in the following decreasing order: Au³⁺>Pt⁴⁺>Mn²⁺>Cu²⁺>Cr³⁺>Fe³⁺. On the basis of the applicability of a non-isothermal kinetic equation, the decomposition process was a first-order reaction. The activation energy, Ea, the entropy change, ΔS ^*, the enthalpy change, ΔH ^* and the Gibbs free energy of activation, ΔG ^* were calculated by applying the theory of the reaction rates. The effect of the different central metal ions on the calculated thermodynamic activation parameters was discussed. This revised version was published online in July 2006 with corrections to the Cover Date.