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Alessandro Castrogiovanni Patrick Herr Dr. Christopher B. Larsen Dr. Xingwei Guo Prof. Dr. Christof Sparr Prof. Dr. Oliver S. Wenger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16748-16754
Atropisomeric 1,2-naphthylene scaffolds provide access to donor–acceptor compounds with helical oligomer-based bridges, and transient absorption studies revealed a highly unusual dependence of the electron-transfer rate on oligomer length, which is due to their well-defined secondary structure. Close noncovalent intramolecular contacts enable shortcuts for electron transfer that would otherwise have to occur over longer distances along covalent pathways, reminiscent of the behavior seen for certain proteins. The simplistic picture of tube-like electron transfer can describe this superposition of different pathways including both the covalent helical backbone, as well as noncovalent contacts, contrasting the wire-like behavior reported many times before for more conventional molecular bridges. The exquisite control over the molecular architecture, achievable with the configurationally stable and topologically defined 1,2-naphthylene-based scaffolds, is of key importance for the tube-like electron transfer behavior. Our insights are relevant for the emerging field of multidimensional electron transfer and for possible future applications in molecular electronics. 相似文献
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A synthetic route has been developed for incorporating pyrazoline derivatives as proline surrogates in constrained X-Pro peptidomimetics. The route allows for the synthesis of dipeptide building blocks having either a six or seven-membered-ring annulated onto the pyrazoline moiety, as well as for the asymmetric synthesis of analogs having substituents on N-terminal side of the building block. 相似文献
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Virgil Percec Anatoliy V. Popov Ernesto Ramirez‐Castillo Oliver Weichold 《Journal of polymer science. Part A, Polymer chemistry》2004,42(24):6364-6374
The accelerated single electron transfer–degenerative chain transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran (THF) at 25 °C is reported. This process is catalyzed by sodium dithionite (Na2S2O4)‐sodium bicarbonate (NaHCO3). Electron transfer cocatalysts (ETC) 1,1′‐dialkyl‐4,4′‐bipyridinum dihalides or alkyl viologens were also employed in this polymerization. The resulting poly(vinyl chloride) (PVC) has a number‐average molecular weight (Mn) = 2,000–12,000, no detectable amounts of structural defects, and both active chloroiodomethyl and inactive chloromethyl chain ends. The molecular weight distribution of PVC obtained is Mw/Mn = 1.5. The surface active agents afford the final polymers as a powder and provide an acceleration of the rate of polymerization. The role of ETC is to accelerate the single electron transfer (SET) step, whereas THF enhances the degenerative chain transfer (DT) step. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6364–6374, 2004 相似文献
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