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1.
A multivariate calibration method was applied to improve the accuracy of the determination of cadmium in the presence of potassium by total reflection X-ray fluorescence (TXRF). Due to TXRF's relatively low resolution, a particular interference caused by potassium at line Kα 3.31 keV as interference can compromise the cadmium determination at line Lα 3.13 keV, respectively. The method is based on the hypothesis that the application of a multivariate calibration method, for example, partial least squares, could reduce variations due to interference and, consequently, improve the selectivity and accuracy in Cd determination. In this work, this strategy was evaluated on the X-ray fluorescence emission signals between 2.50 and 3.90 keV for a set of 26 different synthetic calibration mixtures and eight different mixtures for external calibration. Based on a certified reference material (Clay 2—CRM051) with high potassium levels, a significant improvement of accuracy for cadmium determination was observed, overcoming the problems associated with spectral interferences by potassium. 相似文献
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Back Cover: Experimental and Theoretical Study of the Reactivity of Gold Nanoparticles Towards Benzimidazole‐2‐ylidene Ligands (Chem. Eur. J. 30/2016) 下载免费PDF全文
Dr. María Rodríguez‐Castillo Gustavo Lugo‐Preciado Dr. Danielle Laurencin Dr. Frederik Tielens Dr. Arie van der Lee Dr. Sébastien Clément Dr. Yannick Guari Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. Françoise Remacle Dr. Sébastien Richeter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10680-10680
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Potential Analysis - Given a metric measure space $(X,d,\mathfrak {m})$ that satisfies the Riemannian Curvature Dimension condition, RCD?(K,N), and a compact subgroup of isometries G ≤... 相似文献
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Optimization Letters - Differential evolution (de) is a popular population-based meta-heuristic that has been successfully used in complex optimization problems. Premature convergence is one of the... 相似文献
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Laura Ortiz-Rojano Jaime Rojas-Martín Ciro Rodríguez-Diaz Prof. Dr. M. Carmen Carreño Prof. Dr. Maria Ribagorda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(66):15050-15054
Quinones were firstly used as dipolarophiles in a photoclick 1,3-cycloaddition with 2,5-diaryltetrazoles, as photoactivatable predipoles, providing a novel and efficient access to three types of pyrazole-fused quinones (indazoledione derivatives). Distinctive features of this protocol include the use of light as the unique reagent and readily available, stable, and easy to handle starting materials and good to excellent yields. Photophysical and electrochemical properties of the quinones and their potential application as photoredox catalysts are also detailed. 相似文献
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Rebeca G. Castillo Justin T. Henthorn Jeremy McGale Dimitrios Maganas Serena DeBeer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):13065-13075
In recent years, X-ray emission spectroscopy (XES) in the Kβ (3p-1s) and valence-to-core (valence-1s) regions has been increasingly used to study metal active sites in (bio)inorganic chemistry and catalysis, providing information about the metal spin state, oxidation state and the identity of coordinated ligands. However, to date this technique has been limited almost exclusively to first-row transition metals. In this work, we present an extension of Kβ XES (in both the 4p-1s and valence-to-1s [or VtC] regions) to the second transition row by performing a detailed experimental and theoretical analysis of the molybdenum emission lines. It is demonstrated in this work that Kβ2 lines are dominated by spin state effects, while VtC XES of a 4d transition metal provides access to metal oxidation state and ligand identity. An extension of Mo Kβ XES to nitrogenase-relevant model complexes shows that the method is sufficiently sensitive to act as a spectator probe for redox events that are localized at the Fe atoms. Mo VtC XES thus has promise for future applications to nitrogenase, as well as a range of other Mo-containing biological cofactors. Further, the clear assignment of the origins of Mo VtC XES features opens up the possibility of applying this method to a wide range of second-row transition metals, thus providing chemists with a site-specific tool for the elucidation of 4d transition metal electronic structure. 相似文献
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Armando Berlanga-Vázquez Radu A. Talmazan Carlos A. Reyes-Mata Prof. Edmundo G. Percástegui Dr. Marcos Flores-Alamo Prof. Maren Podewitz Prof. Ivan Castillo 《欧洲无机化学杂志》2023,26(6):e202200596
Functionalization of the phenolic rim of p-tert-butylcalix[8]arene with phenanthroline to create a cavity leads to formation of two regioisomers. Substitution of positions 1 and 5 produces the known C2v-symmetric regioisomer 1,5-(2,9-dimethyl-1,10-phenanthroyl)-p-tert-butylcalix[8]arene ( L1,5 ), while substitution of positions 1 and 4 produces the Cs-symmetric regioisomer 1,4-(2,9-dimethyl-1,10-phenanthroyl)-p-tert-butylcalix[8]arene ( L1,4 ) described herein. [ Cu(L1,4)I ] was synthesized from L1,4 and CuI in good yield and characterized spectroscopically. To evaluate the effect of its cavity on catalysis, Ullmann-type C−S coupling was chosen as proof-of-concept. Selected aryl halides were used, and the results compared with the previously reported Cu(I)/ L1,5 system. Only highly activated aryl halides generate the C−S coupling product in moderate yields with the Cu(I)/ L1,4 system. To shed light on these observations, detailed computational investigations were carried out, revealing the influence of the calix[8]arene macrocyclic morphology on the accessible conformations. The L1,4 regioisomer undergoes a deformation that does not occur with L1,5 , resulting in an exposed catalytic center, presumably the cause of the low activity of the former system. The 1,4-connectivity was confirmed in the solid-state structure of the byproduct [ Cu(L1,4 − H) (CH3CN)2] that features Cu(I) coordinated inside a cleft defined by the macrocyclic framework. 相似文献
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