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排序方式: 共有166条查询结果,搜索用时 15 毫秒
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A. Vikas Aggarwal Dr. Stefan‐S. Jester Sara Mehdizadeh Taheri Prof. Dr. Stephan Förster Prof. Dr. Sigurd Höger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(14):4480-4495
We present the efficient synthesis of a new molecular spoked‐wheel structure ( MSW‐3 ). Two derivatives with diameters of approximately 4 nm have been prepared. By highlighting the importance of pseudo‐high‐dilution conditions during cyclization, we were able to access the compounds on a several hundred milligram scale. In addition to the standard characterization (NMR spectroscopy, MS), we describe a detailed investigation of the optical properties of the fluorescent MSWs by comparison with appropriate model chromophores. Furthermore, a comprehensive study of the structure in solution by means of light‐ and X‐ray scattering experiments has been conducted. Scanning tunneling microscopy (STM) revealed the two‐dimensional organization of the molecules on highly oriented pyrolytic graphite and emphasized the spoked‐wheel structure. The diameter of these molecules measured by small‐angle X‐ray scattering is in very good agreement with that obtained from STM and matches the results of molecular modeling. This confirms the rigidifying effect of the spokes, which results in highly shape‐persistent nanometer‐sized oblate organic compounds. 相似文献
113.
The synthesis and the optical and electrochemical properties of 2-aryl-2H-benzotriazole based thiophene oligomers with chemical modifications either on the phenyl side group or on the backbone are presented. All data, supported by DFT calculations, show that modification on the backbone has a major impact on the electronic properties while the side groups can fine-tune the electronic properties. In addition, one compound exhibits a thermotropic mesophase. 相似文献
114.
Maier SK Jester SS Müller U Müller WM Höger S 《Chemical communications (Cambridge, England)》2011,47(39):11023-11025
A route towards phenylene-bithiophene macrocycles via oxidative thiophene coupling under pseudo-high dilution conditions is reported. This method is applied to the synthesis of a shape-persistent thiophene macrocycle with extraannularly attached perylenebisimide moieties that forms supramolecular aggregates at the solid/liquid interface. 相似文献
115.
Marte Sofie Martinsen Holmsen Ainara Nova Sigurd
ien‐
degaard Richard H. Heyn Mats Tilset 《Angewandte Chemie (International ed. in English)》2020,59(4):1516-1520
A highly asymmetric AuIII η3‐allyl complex has been generated by treating Au(η1‐allyl)Br(tpy) (tpy=2‐(p‐tolyl)pyridine) with AgNTf2. The resulting η3‐allyl complex has been characterized by NMR spectroscopy and X‐ray crystallography. DFT calculations and variable temperature 1H NMR suggest that the allyl ligand is highly fluxional. 相似文献
116.
Mark Vanderkelen Sigurd Schelstraete Henri Verschelde 《Zeitschrift fur Physik C Particles and Fields》1997,75(2):375-381
We present a variational approach to calculate the vacuum energy of a hermitian matrix model. The approach generalizes a previously proposed non-perturbative technique (the 2PPI expansion) to fields which carry an additional tensor structure. The method works for any number of space-time dimensions and produces good results over the whole range of the coupling constant and the matrix order. We study the 0- and 1-dimensional case. 相似文献
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