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De Cat I Guo Z George SJ Meijer EW Schenning AP De Feyter S 《Journal of the American Chemical Society》2012,134(6):3171-3177
An achiral oligo(p-phenylene vinylene) derivative with a ureido-triazine hydrogen bonding unit self-assembles into rows of hydrogen bonded dimers at the liquid/solid interface. Scanning tunneling microscopy reveals the formation of chiral domains, but overall, the surface remains racemic. Addition of a chiral auxiliary which is able to interact with the dimers through hydrogen bonding, showed that global organizational chirality could be achieved since a majority of the domains show the same handedness. After removing the chiral auxiliary with a volatile solvent, the global organizational chirality could be trapped, revealing a memory effect. With this straightforward supramolecular approach, we were able to create a chiral surface with preferred handedness composed of achiral molecules at the air/solid interface. 相似文献
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María Moreno Oliva Juan Casado Dr. Juan T. López Navarrete Prof. Gunther Hennrich Dr. Stijn van Cleuvenbergen Dr. Inge Asselberghs Dr. Koen Clays Dr. M. Carmen Ruiz Delgado Dr. Jean‐Luc Brédas Prof. J. Sérgio Seixas de Melo Prof. Luisa De Cola Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(33):8223-8234
We have synthesized three new molecules that have three thienylethynyl arms substituting a central benzene core and different electron donor/acceptor groups in the three remaining phenyl positions. The absorption, fluorescence, phosphorescence, and transient triplet–triplet spectra are analyzed in the light of the electronic structure of the ground and excited states obtained from quantum‐chemical calculations. From the above, the relevant photophysical data (including quantum yields, lifetimes, and rate constants) could be derived. It was found that the major deactivation pathway is internal conversion, which competes with the fluorescence and intersystem crossing processes. For the three investigated compounds, we provide convincing theoretical support corroborating these findings and further conclusions based on the theoretical information obtained. These molecules are one of the very few cases in which the depolarization ratios, obtained from the NLO optical measurements, clearly reflect the octopolar configuration. Molecular hyperpolarizabilities have been measured and display a typical dependence on the donor–acceptor substitution pattern. 相似文献
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