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1.
Novel mixed valence states have been obtained by the treatment of cobaltous ferrocyanides (Co+2FeII) and ferricyanides (Co+2FeIII) in an ozone flow. The CN stretching bands occur at 2085 cm–1 for Co+2FeII and at 2160 cm–1 for Co+2FeIII. After the ozonization process of Co+2FeII, an intense band approximately at 2125 cm–1 is detected. This intermediate band must correspond to a mixed valence state of the type: FeII–CN–Co2+–NC–FeIII Mössbauer spectra recorded in situ during the ozonization of Co+2FeII show the presence of two components: a doublet with isomer shift and quadrupole splitting values close to the cobalti ferricyanide and a very broad line for the mixed valence state. From the Mössbauer and infrared spectra of the aged samples of the Co+2FeII after ozonization, a relaxation process to the initial state of the samples is observed but the mixed valence state is stable. 相似文献
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ZHOU Cheng-He Juan F.Miravet M.Isabel Burguete Santiago V.Luis BAI Xue YUAN Yong 《有机化学》2004,24(Z1):380
Polynitrogen receptors such as bis-histidine peptides possess strong ability to bind metals, which play much important roles in medicinal, bioinorganic, bioorganic, biomimetic and supramolecular chemistry. In order to investigate the interaction of these hosts with a variety of neutral, cationic and anionic guests, several techniques, for example, NMR,potentiometric tirations and monocrystal X-ray diffraction have been employed. Among them NMR is a powerful technique for unraveling the structure of polynitrogen receptors as long as they are in solution where the rapid tumbling of molecules averages out the anisotropies such as chemical shift and dipole-dipole interactions. General 1H NMR approach has been widely used for the study of host-guest interaction, but it is difficult for the accurate measurement in complexes structures, particularly metal complexes structures in which how the polynitrogen receptors bind metal, and which nitrogen binds metal and so on. 相似文献
4.
A new method for the speciation of inorganic [Sb(III) and Sb(V)] and organic (Me3SbCl2) antimony species by using a polystyrene-divinylbenzene-based anion-exchange HPLC column (Hamilton PRP-X100) coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) is presented. Several mobile phases were tested for the baseline separation of these three antimony species, investigating in detail experimental parameters such as concentration and pH. The best efficiency and resolution was achieved by using a gradient elution between diammonium tartrate 250 mmol l(-1) pH 5.5 (A) and KOH 20 mmol l(-1) pH 12 (B). The gradient programme used was 100% B for 1.5 min, decreasing to 0% B in 0.1 min and maintained the elution with 100% A for 5.5 min. Analysis time was less than 7 min. Equilibration of the column with the complexing mobile phase was found to be critical in order to avoid Sb(III) double peak formation. Dilution in diammonium tartrate medium was necessary in order to avoid Sb(III) oxidation at microg l(-1) concentration level. Detection limits of 0.06 microg l(-1) for Sb(V), 0.09 microg l(-1) for Me3SbCl2 and 0.04 microg l(-1) for Sb(III) as well as repeatability and reproducibility better than 5% R.S.D. (n = 10) and 9% R.S.D. (n = 30) (for 1 and 5 microg l(-1) of Sb(V) and Sb(III) and 5 and 10 microg l(-1) of Me3SbCl2) were obtained. Accuracy and recovery studies were carried out by analysing one river freshwater sample and two water certified reference materials. The proposed methodology can be considered reliable and straightforward for antimony speciation in fresh water samples. 相似文献
5.
Makins NC Ent R Chapman MS Hansen J Lee K Milner RG Nelson J Arnold RG Bosted PE Keppel CE Lung A Rock SE Spengos M Szalata ZM Tao LH White JL Coulter KP Geesaman DF Holt RJ Jackson HE Papavassiliou V Potterveld DH Zeidman B Arrington J Beise EJ Belz E Filippone BW Gao H Lorenzon W Mueller B McKeown RD O'Neill TG Epstein M Margaziotis DJ Napolitano J Kinney E Anthony PL van Bibber K Dietrich FS Gearhart RA Patratos GG Kuhn SE van den Brand JF Bulten H Jones CE 《Physical review letters》1994,72(13):1986-1989
6.
Freezing Capture of Polymorphic Aggregates of Bolaamphiphilic L‐Valine‐Based Molecular Hydrogelators 下载免费PDF全文
Dr. Vicent J. Nebot Dr. Santiago Díaz‐Oltra Dr. Johan Smets Susana Fernández Prieto Dr. Juan F. Miravet Dr. Beatriu Escuder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5762-5767
Nanostructured xerogels have been prepared by the freeze‐drying of hydrogels and aggregates formed by bolaamphiphilic L ‐valine derivatives after aging under different environmental conditions. A wide variety of shapes and sizes has been achieved by a simple methodology. These nanostructures have been studied by SEM and WAXD and a dramatic influence of structural flexibility on the kinetics of aggregation has been observed. Such flexibility and a modulation of the hydrophobic effect have shown a profound influence in the packing of these compounds and revealed a high degree of polymorphism. 相似文献
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van den Brand JF Ent R Anthony PL Arnold RG Arrington J Beise EJ Belz JE Bosted PE Bulten H Chapman MS Coulter KP Dietrich FS Epstein M Filippone BW Gao H Gearhart RA Geesaman DF Hansen J Holt RJ Jackson HE Jones CE Keppel CE Kinney ER Kuhn S Lee K Lorenzon W Lung A Makins NC Margaziotis DJ McKeown RD Milner RG Mueller B Napolitano J Nelson J O'Neill TG Papavassiliou V Petratos GG Potterveld DH Rock SE Spengos M Szalata ZM Tao LH van Bibber K Wasson DA White JL Zeidman B 《Physical review D: Particles and fields》1995,52(9):4868-4871
9.
A systematic study of antimony reduction prior to its determination by hydride generation atomic fluorescence spectrometry (HG-AFS) was carried out. The efficiency of l-cysteine, potassium iodide and potassium iodide/ascorbic acid was studied for this purpose. The hydride generation step was optimised in the presence of those pre-reductors. From the results, l-cysteine was found to be the most suitable pre-reducing agent. Methodology was validated, obtaining detection limits lower than 90 ng l−1 and repeatability and reproducibility better than 3% R.S.D. and 5% R.S.D., respectively, in all cases. In order to evaluate the methodology developed and the influence of the matrix, recovery from waters from different sources was tested by HG-AFS and also by inductively coupled plasma mass spectrometry (ICP-MS). Accuracy was assessed by analysing three water reference materials at different antimony concentration levels. The high sensitivity of the developed methodology enables it to be applied for monitoring drinking waters according to the maximum admissible concentration of antimony established by the EU Directives. 相似文献
10.
Becerril J Burguete MI Escuder B Luis SV Miravet JF Querol M 《Chemical communications (Cambridge, England)》2002,(7):738-739
L-Valine containing cyclophanes have been shown to gelate organic solvents leading to soft materials with a clear expression of their chirality at the supramolecular level. 相似文献