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排序方式: 共有495条查询结果,搜索用时 31 毫秒
491.
Camiel C. E. Kroonen Adriano D'Addio Alessandro Prescimone Olaf Fuhr Dieter Fenske Marcel Mayor 《Helvetica chimica acta》2023,106(4):e202200204
The exploration of new materials is timeless. Especially 2D-materials have gotten much interest in the last decades. This work proposes a new route towards a fascinating class of 2D materials: molecular textiles. The suggested bottom-up approach focuses on the 2D self-assembly of a cross-shaped monomer at the water/air interface. A 3D cross-shaped motive was designed, synthesized, and characterized, which exhibits the required structural features, i. e., static and dynamic control. Analysis of the cross-shaped motive by 1H-NMR spectroscopy, X-ray structure, and chiral stationary phase HPLC proved the rigidity and stability of the system, and thus also its potential for the here suggested new strategy towards molecular textiles. Three variants of a Schiff-base precursor pair functionalized monomer were synthesized and characterized by 1H-NMR spectroscopy, 13C-NMR spectroscopy, and mass spectrometry. Finally, the network formation of the monomer is shown to be triggered by deprotonation of its ammonium salt, corroborated with FT-IR analysis. 相似文献
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493.
Viviane Fassina Carolina Ramminger Marcus Seferin Raquel S. Mauler Roberto F. de Souza Adriano L. Monteiro 《Macromolecular rapid communications》2003,24(11):667-670
The oxidative addition of benzyl chloride to Ni(cod)2 in the presence of 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediimine followed by chloride abstraction affords [(η3‐CH2C6H5)Ni(α‐diimine)][PF6] (α‐diimine = 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediimine) in 70% yield. The complex is active in ethylene polymerization in the presence of methylaluminoxane and under mild reaction conditions. The polyethylenes obtained are highly branched, have very low densities, do not show Tm or measurable crystallinity and have molecular weights ranging from 80 × 103 to 290 × 103 g · mol−1.
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One of the most effective methods for gaining insight into the composition of trace-level volatile organic characteristics of wine products is through the use of a comprehensive two-dimensional gas chromatography-high resolution mass spectrometry (GC × GC-HRMS) technique. The vast amount of data generated by this method, however, can often be overwhelming requiring exhaustive and time-consuming analysis to identify significant statistical characteristics. The use of advanced chemometric software can achieve the same or even higher efficiency. This study aimed to identify differences based on geographical locations by analyzing the volatile organic compounds in the composition of botrytized wines from Slovakia, Hungary, France, and Austria. The volatile organic compounds were extracted by solid-phase microextraction and analyzed using GC × GC-HRMS. The data obtained from the analysis underwent Fisher-ratio (F-ratio) tile-based analysis to identify statistically significant differences. Principal component analysis demonstrated a significant distinction between wine samples based on geographical location, using only 10 statistically significant features with the highest F-ratio. In the samples, the following compounds were analyzed: methyl-octadecanoate, 2-cyanophenyl-β-phenylpropionate, α-ionone, n-octanoic acid, 1,2-dihydro-1,1,6-trimethyl-naphthalene, methyl-hexadecanoate, ethyl-pentadecanoate, ethyl-decanoate, and γ-nonalactone. These, all play an important role in cluster pattern observed on principal component analysis results. Additionally, hierarchical cluster analysis confirmed this. 相似文献