Home About us Contact
|
Home About us Contact | ||
|
|
||
Trivalent Metal Ions (trivalent + metal_ion)
Selected AbstractsChemInform Abstract: Light-Emitting meso-Structured Sulfides with Hexagonal Symmetry: Supramolecular Assembly of [Ge4S10]4- Clusters with Trivalent Metal Ions and Cetylpyridinium Surfactant.CHEMINFORM, Issue 4 2001K. Kasthuri Rangan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Experimental and theoretical study of recovery mechanism of impurity effect by the addition of EDTACRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2007Y. Asakuma Abstract The impurity effect by trivalent metal ion such as Al3+, Fe3+ and Cr3+ during crystal growth of KDP is reasonably well documented. If a metal ion is adsorbed onto the crystal surface, it prevents the step propagation relevant to the crystal growth rate. However, this impurity adsorption mechanism is still not well understood. Recently, in our work on the addition of chelate agents, a recovery effect of the metal ion adsorption was discovered. However, its recovery mechanism is not clearly understood both theoretically and phenomenally. In this research, ethylene-diamine-tetra-acetic acid, EDTA, which is the most common chelate agent, was used as a recovery agent. The recovery mechanism was considered from the correlation of experimental data and the interfacial distribution model that we proposed in our former study. Furthermore, quantum calculation of EDTA metal complex can explain the relaxation of impurity adsorption by the addition of EDTA. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Metal ion attachment to the matrix meso-tetrakis(pentafluorophenyl)porphyrin, related matrices and analytes: an experimental and theoretical study,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 11 2009Jeroen J. A. van Kampen Abstract In a previous study [van Kampen et al.Analytical Chemistry 2006; 78: 5403], we found that meso-tetrakis (pentafluorophenyl)porphyrin (F20TPP), in combination with lithium salts, provides an efficient matrix to cationize small molecules by Li+ attachment and that this combination can be successfully applied to the quantitative analysis of drugs, such as antiretroviral compounds using matrix-assisted laser desorption ionization in conjunction with a time-of-flight analyzer (MALDI,TOF). In the present study, we further explore the mechanism of metal ion attachment to F20TPP and analytes by MALDI,FTMS(/MS). To this end, we have studied the interaction of F20TPP and analytes with various mono-, di- and trivalent metal ions (Li+, Na+, K+, Rb+, Cs+, Co2+, Cu2+, Zn2+, Fe2+, Fe3+ and Ga3+). For the alkali cations, we find that F20TPP forms complexes only with Li+ and Na+; in addition, model analyte molecules such as poly(ethyleneglycol)s, mixed with F20TPP and the alkali cations, also only form Li+ and Na+ adducts. This contrasts sharply with the commonly used matrix 2,5-dihydroxybenzoic acid, where analytes are most efficiently cationized by Na+ or K+. Reasons for this difference are delineated. Ab initio calculations on porphyrin itself reveal that even the smallest alkali cation, Li+, does not fit in the porphyrin cavity, but lies on top of it, pushing the 21H and 23 H hydrogen atoms out of and below the plane with concomitant bending of the porphyrin skeleton in the opposite direction, i.e. toward the cation. Thus, the Li+ ion is not effectively sequestered and is in fact exposed and thus accessible for donation to analyte molecules. Interaction of F20TPP with di- and trivalent metal ions leads to protoporphyrin,metal ions, where the metal ion is captured within the protoporphyrin dianion cavity. The most intense signal is obtained when F20TPP is reacted with CuCl2 and then subjected to laser ablation. This method presents an easy general route to study the metal containing protoporphyrin molecules, which could all act as potential MALDI matrices. Copyright © 2009 John Wiley & Sons, Ltd. [source] Evaluation of the metal binding properties of a histidine-rich fusogenic peptide by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 11 2003Andrea Sinz Abstract Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) was used to investigate metal ion interactions of the 18 amino acid peptide fragment B18 (LGLLLRHLRHHSNLLANI), derived from the membrane-associated protein bindin. The peptide sequence B18 represents the minimal membrane-binding motif of bindin and resembles a putative fusion peptide. The histidine-rich peptide has been shown to self-associate into distinct supramolecular structures, depending on the presence of Zn2+ and Cu2+. We examined the binding of B18 to the metal ions Cu2+, Zn2+, Mg2+, Ca2+, Mn2+ and La3+. For Cu2+, we compared the metal binding affinities of the wild-type B18 peptide with those of its mutants in which one, two or three histidine residues have been replaced by serines. Upon titration of B18 with Cu2+ ions, we found sequential binding of two Cu2+ ions with dissociation constants of ,34 and ,725 µM. Mutants of B18, in which one histidine residue is replaced by serine, still exhibit sequential binding of two copper ions with affinities for the first Cu2+ ion comparable to that of wild-type B18 peptide, but with a greatly reduced affinity for the second Cu2+ ion in mutants H112S and H113S. For mutants in which two histidines are replaced by serines, the affinity for the first Cu2+ ion is reduced ,3,10 times in comparison with B18. The mutant in which all three histidine residues are replaced by serines exhibits an ,14-fold lower binding for the first Cu2+ ion compared with B18. For the other metal ions under investigation (Zn2+, Mg2+, Ca2+, Mn2+ and La3+), a modest affinity to B18 was detected binding to the peptide in a 1 : 1 stoichiometry. Our results show a high affinity of the wild-type fusogenic peptide B18 for Cu2+ ions whereas the Zn2+ affinity was found to be comparable to that of other di- and trivalent metal ions. Copyright © 2003 John Wiley & Sons, Ltd. [source] Water-soluble anionic conjugated polymers for metal ion sensing: Effect of interchain aggregationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2009Yi Chen Abstract Three sulfonato-containing fluorene-based anionic water-soluble conjugated polymers, which are specially designed to link fluorene with alternating moieties such as bipyridine (P1), pyridine (P2), and benzene (P3) have been synthesized via the Pd-catalyzed Sonogashira-coupling reaction, respectively. These polymers had good solubility in water and showed different responses for transition metal ions with different valence in aqueous environments: the fluorescence of bipyridine-containing P1 can be completely quenched by addition of all transition metal ions selected and showed a good selectivity for Ni2+; the pyridine-containing P2 had a little response for monovalent and divalent metal ions while showed good quenching with the addition of trivalent metal ions (with a special selectivity for Fe3+); P3 had responses only for the trivalent metal ions within the ionic concentration we studied. After investigation of the UV-vis absorption spectra, PL emission spectra, DLS, and fluorescence lifetime of P1,P3 in aqueous solution when adding transition metal ions, we found that the different spectrum responses of these polymers are attributed to the different coordination ability of the units linked with fluorene in the main chain. The energy or electron-transfer reactions were the main reason for fluorescence quenching of P1 and P2. On the other hand, interchain aggregation caused by trivalent metal ions lead to fluorescence quenching for P3 and also caused partly fluorescence quenching of P1 and P2. These results revealed the origin of ionochromic effects of these polymers and suggested the potential application for these polymers as novel chemosensors with higher sensing sensitivity in aqueous environments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5057,5067, 2009 [source] Effects of some trivalent metal ions on the fluoride-induced chemiluminescence from a phenylphosphate-substituted dioxetane Lumigen PPDLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 5 2002Mojtaba Shamsipur Abstract The chemiluminescene generated from the reaction of a thermally stable phenylphosphate-substituted dioxetane Lumigen PPD at ambient temperature was studied in DMSO solution. The presence of trivalent metal ions Cr3+, Ga3+, Fe3+ and Al3+ was found to quench the resulting chemiluminescence dramatically. The system resulted in nice Stern,Volmer plots in the quencher concentration range 1.5,×,10,4,1.8,×,10,3,mol/L. The KQ values decreased in the order Cr3+,>,Ga3+,>,Fe3+,>,Al3+. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||