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111.
Mark A. Newton Marco Di Michiel Davide Ferri Marcos Fernàndez-Garcia Andrew M. Beale Simon D. M. Jacques Peter J. Chupas Karena W. Chapman 《Catalysis Surveys from Asia》2014,18(4):134-148
Very high energy X-rays (ca. >40 keV) have long offered great promise in providing great insight into the inner workings of catalysts; insights that may complement the battery of techniques available to researchers in catalysis either in the laboratory or at more conventional X-ray wavelengths. This contribution aims to critically assess the diverse possibilities now available in the high energy domain as a result of the maturation of third generation synchrotron facilities and to look forward to the potential that forthcoming developments in synchrotron source technology may offer the world of catalysis in the near future. 相似文献
112.
Anna Liguori Tommaso Gallingani Dilli Babu Padmanaban Romolo Laurita Tamilselvan Velusamy Gunisha Jain Manuel Macias-Montero Davide Mariotti Matteo Gherardi 《Plasma Chemistry and Plasma Processing》2018,38(6):1209-1222
The influence of the liquid composition on the chemical and morphological properties of copper-based nanostructures synthesized by a non-equilibrium atmospheric plasma treatment is investigated and discussed. The synthesis approach is simple and environmentally friendly, employs a non-equilibrium nanopulsed atmospheric pressure plasma jet as a contactless cathode and a Cu foil as immersed anode. The process was studied using four distinct electrolyte solutions composed of distilled water and either NaCl?+?NaOH, NaCl only or NaOH only at two different concentrations, without the addition of any copper salts. CuO crystalline structures with limited impurities (e.g. Cu and Cu(OH)2 phases) were produced from NaCl?+?NaOH containing solutions, mainly CuO and CuCl2 structures were synthesized in the electrolyte solution containing only NaCl and no synthesis occurred in solutions containing only NaOH. Both aggregated and dispersed nanostructures were produced in the NaCl?+?NaOH and NaCl containing solutions. Reaction pathways leading to the formation of the nanostructures are proposed and discussed. 相似文献
113.
Dr. Andrey Berezin Nicolas Biot Tommaso Battisti Prof. Dr. Davide Bonifazi 《Angewandte Chemie (International ed. in English)》2018,57(29):8942-8946
The synthesis of a zig‐zag oxygen‐doped molecular rhombic ribbon has been achieved. This includes oxidative C?C and C?O bond formations that allowed the stepwise elongation and planarization of an oxa‐congener of 2,7‐periacenoacene. X‐ray diffraction analysis corroborated the flat structure and the zig‐zag topology of the O‐doped edges. Photophysical and electrochemical investigations showed that the extension of the peri‐xanthenoxanthene (PXX) into the molecular ribbon induces a noticeable shrinking of the molecular band gap devised by a rising of the HOMO energy level, a desirable property for p‐type organic semiconductors. 相似文献
114.
Bencivenni G Lanza T Leardini R Minozzi M Nanni D Spagnolo P Zanardi G 《Organic letters》2008,10(6):1127-1130
Homolytic substitution at the sulfur atom of beta-(phenylsulfanyl)vinyl radicals, obtained by radical reaction of benzenethiol with easily accessible alkyl 4-pentynyl sulfides, is a mild, effective, tin-free route for the generation of all types of alkyl radicals. This protocol can be employed in reductive defunctionalizations as well as cyclizations onto both electron-rich and electron-poor C-C double bonds. 相似文献
115.
Timmons SC Hui JP Pearson JL Peltier P Daniellou R Nugier-Chauvin C Soo EC Syvitski RT Ferrières V Jakeman DL 《Organic letters》2008,10(2):161-163
A bacterial alpha-d-glucopyranosyl-1-phosphate thymidylyltransferase was found to couple four hexofuranosyl-1-phosphates, as well as a pentofuranosyl-1-phosphate, with deoxythymidine 5'-triphosphate, providing access to furanosyl nucleotides. The enzymatic reaction mixtures were analyzed by electrospray ionization mass spectrometry and NMR spectroscopy to determine the anomeric stereochemistry of furanosyl nucleotide products. This is the first demonstration of a nucleotidylyltransferase discriminating between diastereomeric mixtures of sugar-1-phosphates to produce stereopure, biologically relevant furanosyl nucleotides. 相似文献
116.
117.
Multiphoton fabrication 总被引:1,自引:0,他引:1
LaFratta CN Fourkas JT Baldacchini T Farrer RA 《Angewandte Chemie (International ed. in English)》2007,46(33):6238-6258
Chemical and physical processes driven by multiphoton absorption make possible the fabrication of complex, 3D structures with feature sizes as small as 100 nm. Since its inception less than a decade ago, the field of multiphoton fabrication has progressed rapidly, and multiphoton techniques are now being used to create functional microdevices. In this Review we discuss the techniques and materials used for multiphoton fabrication, the applications that have been demonstrated, as well as those being pursued. We also consider the outlook for this field, both in the laboratory and in industrial settings. 相似文献
118.
The self-assembly of a thymine nucleotide-calixarene hybrid (1) in CDCl3 as a solvent was investigated. FT-IR, ESI-MS, 1H and DOSY-NMR spectra evidenced that compound 1 (ammonium or sodium salt) self-assembles in a triangular trimeric supramolecule by thymine-thymine hydrogen bonding. The saline form is crucial for the arrangement in the cyclic trimer as the protonation of the nucleotide phosphate groups leads the assembly toward a dimeric species. 相似文献
119.
Cataldi TR Rubino A Lelario F Bufo SA 《Rapid communications in mass spectrometry : RCM》2007,21(14):2374-2388
A method for the comprehensive profiling of intact glucosinolates (GLSs), major and minor, occurring in leaves and seeds of rocket salad (Eruca sativa L.) is presented using optimized reversed-phase liquid chromatography (RP-LC) with electrospray ionization (ESI) ion trap mass spectrometry (ITMS). ESI-ITMS in the negative mode was confirmed to be very suitable to analyze these compounds in crude extracts. After extraction from the plant material with methanol/water (70:30 v/v) at 70 degrees C, the analytes of interest were separated on a C18 column using an eluent acidified with formic acid (0.1%) and modified with acetonitrile. All the GLSs found in leaves of rocket salad gave good signals corresponding to the deprotonated precursor ion, [M-H]-. Although the mass spectra also exhibited an analytically important non-covalent adduct ion at [2M-H]-, the structures of glucosinolates were confirmed by extensive sequential MS analysis, thereby substantially improving the identification of unknown compounds. The results obtained not only revealed in leaves of E. sativa at least twelve species of GLSs including seven aliphatic compounds (glucoraphanin with [M-H]- at m/z ratio of 436, glucoerucin at m/z 420, 4-mercaptobutyl-GLS at m/z 406, progoitrin/epiprogoitrin at m/z 388, sinigrin at m/z 358, 4-methylpentyl- and n-hexyl-GLS at m/z 402) and three indole glucosinolates (i.e., three N-heterocyclic compounds: 4-hydroxyglucobrassicin and 5-hydroxyglucobrassicin at m/z 463, and 4-methoxy-glucobrassicin at m/z 477), but also two structurally related compounds containing one intermolecular disulfide linkage (4-(beta-D-glucopyranosyldisulfanyl)butyl-GLS at m/z 600 and a dimeric 4-mercaptobutyl-GLS at m/z 811). This latter symmetric disulfide was previously considered as an artefact formed during extraction of GLSs from vegetative tissues. Glucosinolates were detected in the leaves with a wide range of contents (10-200 micromol/g) and a great variation in the composition. Only three GLSs were identified in seeds of rocket salad, namely glucoraphanin, glucoerucin and 4-methoxyglucobrassicin. As expected, the most abundant GLS in seeds is glucoerucin. The feasibility of the strategy was also demonstrated using a rapeseed extract of certified reference material (BCR367R). The results indicated the usefulness of this method for a rapid, sensitive and comprehensive profiling of the GLS family naturally occurring in extracts of crude plant matter. 相似文献
120.
Adsorption of hydrogen ions from aqueous NaCl solutions at the Pyrex glass-water interface was investigated by acid-base titration (glass electrode) at 25 degrees C and at the ionic strengths 0.010, 0.030, 0.10, 1.0, and 3.0 mol dm(-3). The pH values ranged from 2 to 7. The Pyrex samples had a specific surface area of 19.2x10(3) m(2)kg(-1) and a porous structure (pores 2.4 nm thick, 280 nm long). The reactions were found to be extremely slow but showed good reversibility. The potentiometric data, due to the small effect of ionic strength on the equilibria, were fitted with a simple nonelectrostatic model based on strong specific interactions of medium ions with deprotonated silanol, >SiO(-), and boranol, >BO(-), as well as with protonated sites. The acid-base properties are described by the reactions and equilibrium constants at the infinite dilution reference state: >SiONa + H(+) <==> >SiOHNa(+), logbeta110Si=3.1+/-0.2; >SiONa + 2H(+) + Cl(-) <==> >SiOH(2)Cl + Na(+), logbeta201Si=6.75+/-0.15; >SiONa + H(+) <==> >SiOH + Na(+), logbeta100Si=1.8+/-0.2, >BONa + H(+) <==>BOH + Na(+), logbeta100B=6.4+/-0.2; >BONa + H(+) <==> >BOHNa(+), logbeta110B=6.6+/-0.2; >BONa + 2H(+) <==> >BOH(+)(2) + Na(+), logbeta200B=11.56+/-0.15. 相似文献