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91.
Eladia María Peña‐Méndez Beatriz González Pablo Lorenzo Antonio Romerosa Josef Havel 《Rapid communications in mass spectrometry : RCM》2009,23(23):3831-3836
Ruthenium(II) complexes are of great interest as a new class of cancerostatics with advantages over classical platinum compounds including lower toxicity. The stability of the [RuClCp(mPTA)2](OSO2CF3)2 complex (I) (Cp cyclopentadienyl, mPTA N‐methyl 1,3,5‐triaza‐7‐phosphaadamantane) in aqueous solution was studied using spectrophotometry, matrix‐assisted laser desorption/ionization (MALDI) and laser desorption/ionization (LDI) time‐of‐flight (TOF) mass spectrometry (MS). Spectrophotometry proves that at least three different reactions take place in water. Dissolution of I leads to fast coordination of water molecules to the Ru(II) cation and then slow hydrolysis and ligand exchange of chloride and mPTA with water, hydroxide or with trifluoromethane sulfonate itself. Via MALDI and LDI of the hydrolyzed solutions the formation of singly positively charged ions of general formula RuClp(Cp)q(mPTA)r(H2O)s(OH)t (p = 0–1, q = 0–1, r = 0–2, s = 0–5, t = 0–2) and of some fragment ions was shown. The stoichiometry was determined by analyzing the isotopic envelopes and computer modelling. The [RuClCp(mPTA)2](OSO2CF3)2 complex can be stabilized in dilute hydrochloric acid or in neutral 0.15 M isotonic sodium chloride solution. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
92.
A new matrix separation/preconcentration method is developed for the on-line determination of palladium(II) and platinum(IV) in complex matrices using a sequential ICP-OES instrument. These metals are preconcentrated in a microcolumn packed with Metalfix-Chelamine, a polymeric functionalised resin containing the tetraethylenepentamine group. The hydrodynamic and chemical conditions of the flow system affecting the loading and elution steps are optimised off-line using a mixture of 1.0 mol L−1 thiourea and 2.0 mol L−1 NaClO4 in 4.0 mol L−1 HCl which proved to be the most effective solution for the simultaneous elution of Pd(II) and Pt(IV). High enrichment factors of nearly 35 are achieved for both metals and the detection limits (LOD) are 22 ng L−1 for platinum and 2.5 ng L−1 for palladium. The accuracy of the method was tested by analysing a used pellet catalyst (certified reference material NIST 2556) and trace metal solutions resulting from the leaching of this material. Despite the fact that this CRM contains zirconium and large amounts of aluminium and lead, a high level of agreement was achieved demonstrating the efficiency of the resin in eliminating interfering elements. 相似文献
93.
The properties and behavior of polyethyleneimine (PEI) covalently coated capillaries with respect to different background electrolytes used in capillary zone electrophoresis (CZE) are described. The coating stability and changes of inner surface charge in the capillary were followed by measurement of electroosmotic flow (EOF). Interest was focused mainly on conjugate bases of carboxylic acids as anionic background electrolyte components (acetate, citrate, malate, malonate, tartrate, and succinate). An interesting phenomenon was observed in PEI-coated capillaries: The direction (and the magnitude) of EOF depends on the composition of the background electrolyte and at a certain pH it can undergo reversible change. Ionic complex formation was suggested as a hypothesis to explain this behavior. With this knowledge, the PEI-coated capillary was used for the separation of basic proteins in the above-mentioned background electrolytes. A standard protein mixture of cytochrome c, ribonuclease A, and lysozyme at a concentration of 0.25 mg/mL each was chosen as model sample. 相似文献
94.
95.
A recently discovered anion receptor is jointed by three related macrocycles differing in the number of glycoluril units and type of substitution. The synthesis is carried out in nonpolar solvents compared to aqueous media used in the case of the original macrocycle. The size of macrocycle is controlled by a template. A hexameric macrocycle with benzyl substitution binds halide anions with an affinity exceeding 10(9) M(-1) while a tetrameric analog does not bind any of the investigated anions. 相似文献
96.
Markta Kandrnlov Zoran Kokan Vclav Havel Marek Ne
as Vladimír indel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18350-18353
Reversible covalent bonds play a significant role in achieving the high‐yielding synthesis of mechanically interlocked molecules. Still, only a handful of such bonds have been successfully employed in synthetic procedures. Herein, we introduce a novel approach for the fast and simple preparation of interlocked molecules, combining the dynamic bond character of bis(acyloxy)iodate(I) anions with macrocyclic bambusuril anion receptors. The proof of principle was demonstrated on rotaxane synthesis, with near‐quantitative yields observed in both the classical and “in situ” approach. The rotaxane formation was confirmed in the solid‐state and solution by the X‐ray and NMR studies. Our novel approach could be utilized in the fields of dynamic combinatorial chemistry, supramolecular polymers, or molecular machines, as well inspire further research on molecules that exhibit dynamic behavior, but owing to their high reactivity, have not been considered as constituents of more elaborate supramolecular structures. 相似文献
97.
98.
Jan Houka Nagender Reddy Panyala Eladia Maria Pea‐Mndez Josef Havel 《Rapid communications in mass spectrometry : RCM》2009,23(8):1125-1131
Detonation nanodiamonds (NDs) were studied by time‐of‐flight mass spectrometry (TOF MS). The formation of singly charged carbon clusters, C, with groups of clusters at n = 1–35, n ∼160–400 and clusters with n ∼8000 was observed. On applying either high laser energy or ultrasound, the position and intensity of the maxima change and a new group of clusters at n ∼70–80 is formed. High carbon clusters consist of an even number of carbons while the percentage of odd‐numbered clusters is quite low (≤5–10%). On increasing the laser energy, the maximum of ionization (at n ∼200 carbons) is shifted towards the lower m/z values. It is suggested that this is mainly due to the disaggregation of the original NDs. However, the partial destruction of NDs is also possible. The carbon clusters (n ∼2–35) are partially hydrogenated and the average value of the hydrogenation was 10–30%. Trace impurities in NDs like Li, B, Fe, and others were detected at high laser energy. Several matrices for ionizing NDs were examined and NDs themselves can also be used as a matrix for the ionization of various organic compounds. When NDs were used as a matrix for gold nanoparticles, the formation of various gold carbides AumCn was detected and their stoichiometry was determined. It was demonstrated that TOF MS can be used advantageously to analyze NDs, characterize their size distribution, aggregation, presence of trace impurities and surface chemistry. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
99.
Jan Houška Eladia Maria Peña‐Méndez Jakub Kolář Miloslav Frumar Tomáš Wágner Josef Havel 《Rapid communications in mass spectrometry : RCM》2009,23(11):1715-1718
Thin films of AgSbS2 are important for phase‐change memory applications. This solid is deposited by various techniques, such as metal organic chemical vapour deposition or laser ablation deposition, and the structure of AgSbS2(s), as either amorphous or crystalline, is already well characterized. The pulsed laser ablation deposition (PLD) of solid AgSbS2 is also used as a manufacturing process. However, the processes in plasma have not been well studied. We have studied the laser ablation of synthesized AgSbS2(s) using a nitrogen laser of 337 nm and the clusters formed in the laser plume were identified. The ablation leads to the formation of various single charged ternary AgpSbqSr clusters. Negatively charged AgSbS, AgSb2S, AgSb2S, AgSb2S and positively charged ternary AgSbS+, AgSb2S+, AgSb2S, AgSb2S clusters were identified. The formation of several singly charged Ag+, Ag, Ag, Sb, Sb, S ions and binary AgpSr clusters such as AgSb, Ag3S?, SbS (r = 1–5), Sb2S?, Sb2S, Sb3S (r = 1–4) and AgS, SbS+, SbS, Sb2S+, Sb2S, Sb3S (r = 1–4), AgSb was also observed. The stoichiometry of the clusters was determined via isotopic envelope analysis and computer modeling. The relation of the composition of the clusters to the crystal structure of AgSbS2 is discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
100.
Sachinkumar Dagurao Pangavhane Jan Houška Tomáš Wágner Martin Pavlišta Jan Janča Josef Havel 《Rapid communications in mass spectrometry : RCM》2010,24(1):95-102
Ternary chalcogenide As‐S‐Se glasses, important for optics, computers, material science and technological applications, are often made by pulsed laser deposition (PLD) technology but the plasma composition formed during the process is mostly unknown. Therefore, the formation of clusters in a plasma plume from different glasses was followed by laser desorption ionization (LDI) or laser ablation (LA) time‐of‐flight mass spectrometry (TOF MS) in positive and negative ion modes. The LA of glasses of different composition leads to the formation of a number of binary AspSq, AspSer and ternary AspSqSer singly charged clusters. Series of clusters with the ratio As:chalcogen = 3:3 (As3S, As3S2Se+, As3SSe), 3:4 (As3S, As3S3Se+, As3S2Se, As3SSe, As3Se), 3:1 (As3S+, As3Se+), and 3:2 (As3S, As3SSe+, As3Se), formed from both bulk and PLD‐deposited nano‐layer glass, were detected. The stoichiometry of the AspSqSer clusters was determined via isotopic envelope analysis and computer modeling. The structure of the clusters is discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献